US2445649A - Machine for finishing gears - Google Patents

Description

July 20, 1948. 1.. H. TURNER ETAL I 2,445,549

MACHINE FOR FINISHING GEARS Filed N v. e, 1945 1o Sheets-Sheet 1 FIG. I

INVENTOR. LYMAN H. TURNER OLIVER E BAUER By LEONARD c. MICHELSON July 20, 1948. LIH. TURNER ETAL MACHINE FOR FINISHING GEARS 10 Sheets-Sheet 2 Filed Nov. 6, 1945 FIG. 2 f

INVEN TOR. LYMAN H. TURNER OLIVER F. BAUER LEONARDF. MICHELSON July 20, 1948. TURNER ET AL 2,445,649

MACHINE FOR FINISHING GEARS Filed Nov. 6, 1945 l0 Sheets-Sheet 3 INVEN TOR. LYMAN H. TURNER 3 OLIVER F. BAUER y LEONARD c. MICHELSON Jul zo, 194s. L."H. TURNER HAL 2,445,649

MACHINE FOR FINISHING GEARS Filed Nov. 6, 1945 6L0 Sheets-Sheet 4 FIG. 4

INVENTOR.

LYMAN H. TURNER OLIVER F. BAUER y LEONARD c. MICHEISON July 20, 1948. LI'H. TURNER El'AL 2,445,649

MACHINE FOR FINISHING GEARS Filed Nov. 6, 1945 10 Sheets-Sheet 5 INVENTOR. LYMAN H. TURNER OLIVER F. BAUER By LEONARD c. MICHELSON July 20, 1948. L. H. TURNER ETAL 2,445,649

' v MACHINE FOR FINISHING GEARS Filed Nov. 6, 1945 10 Sheets-Sheet 6 FIG. 9

INVENTOR. (I) LYMAN H. TURNER OLIVER F. BAUER w By LEONARD c MICHELSON July 20, 1948.

L; H. TURNER ETAL MACHINE FOR FINISHING GEARS Filed NOV. 6, 1945 10 Sheets-Sheet '7 I\ I, I

3 m I n Q g Q I q k O (\J N 0 INVENTOR. LYMAN H. TURNER OLIVER F BAUER LEONARD C. MICHELSON July 20, 1948. H. TURNER ETAL v MACHINE FOR FINISHING GEARS Filed Nov. .6, 1945 01 8 1O Sheets-Sheet 8 INVENTOR. LYMAN H. TURNER ouvsn F. BAUER LEONARD C, MICHELSON Ju y 20, 194.8- 1.; H. TURNER ETAL 2,445,649

I MACHINE FOR FINISHING GEARS Filed Nov. 6, 1945 10 Sheets-Sheet 9 FIG. l3

FIG. l5

FIG-l6 FIG. I?

INVENTOR. LYMAN H. TURNER OLIVER F. BAUER y LEONARD c. MICHELSON July 20, 1948. LI'H. TURNER EIAL 2,445,549

MACHINE FOR FINISHING GEARS Filed Nqv. 6, 1945 1o Sheets-Sheet 10 FIG. l8

IN VEN TOR. LYMAN H. TURNER OLIVER F. BAUER By LEONARD c. MICHELSON Patented July 20, 1948 UNITED STATES PATENT OFFICE MACHINE FOR FINISHING GEARS Application November 8, 1945, Serial No. 827.024

19 Claims. 1

The present invention relates to machines for finishing gears, and particularly to machines for lapping spiral bevel and hypoid gears.

In lapping bevel and hypoid gears, it is the practice to rotate the gears together in mesh under slight load while efiecting relative motions between the gears lengthwise and traversely of their teeth and in the direction oi tooth depth. In the conventional type of lapping machine, the gear or driven member of the gear pair, which is to be lapped, is mounted on a spindle which is journaled in a quill, that is mounted in an oscillatory carrier for reciprocation in a direction axial of the spindle, and the carrier is mounted for oscillation about an axis parallel to but offset from the axis of the spindle. The lapping operation is 'eflected by reciprocating the quill and oscillating the carrier while the gear and pinion rotate together in mesh. The oscillatory motion 01' the carrier causes the teeth of the driven gear to slide lengthwise over the teeth of the drive gear and it simultaneously moves the gears relative to one another in a direction transverse to the lengthwise sliding. The reciprocatory motion of the quill produces the relative movement of the gears in the direction of tooth depth and serves to maintain the backlash between the gears constant as the teeth slide lengthwise and transversely over one another. The gears are rotated together in one di-. rection for a predetermined period and then reversed. Then, after a predetermined period of drive in the reverse direction, the machine is stopped.

Since opposite sides of the teeth of spiral bevel and hypoid gears are diiIerently curved, one side being longitudinally convex and the other longitudinally concave, it is usually desirable to employ different rates and amounts of lapping motions during the rotation in opposite directions of the gears being lapped. In the conventional lapping machines, the rates of the oscillatory and reciprocator movements are controlled by two difierent sets of change gears, one set controlling the rates of the motions during rotation in one direction of the gears bein lapped and the other set controlling the rates of the motions during rotation of the gears in the opposite direction. The two sets of change gears are automatically shifted into and out of operative position at the time of reversal of the gears being lapped.

In the conventional machines, the position of the axis of the driven spindle can be adjusted angularly about the axis of the carrier. This permits of varying the ratio of the lengthwise and transverse motions of the gears. Nevertheless,

2 a for a given angular position oi the spindle, the ratio of lengthwise to transverse movement is fixed. Therefore, it is not possible to adjust the amount of transverse motion independently oi the amount of lengthwise movement. Further than this, in the conventional machines, the oscillatory motions of the carrier and the reciprocatory movements of the quill are controlled by cams, and, for lapping or burnishing different pairs of gears, diflerent sets of cams must be used, each cam being shaped to suit the job. Moreover, different parts of the cam, which controls the oscillatory motion, have to be used during the forward and reverse rotations of the gears, respectively, and in order to have different amounts of oscillatory movements during forward and reverse rotations, the two parts of the cam have to have diflerent shapes.

The conventional machines, moreover, because of their structure, are suitable only for lapping gears which mesh with axes at right angles. Heretofore no machine has been available for automatically lapping bevel or hypoid gears which mesh with axes at other than right angles, despite the iact that such gears have been used in great numbers.

The primary objects of the present invention are to provide an automatic machine for lappingspiral bevel and hypoid gears which will be more convenient to operate, cheaper in construction, easier to adjust for different jobs and to change over from one job to another, and generally more flexible in use and in range than any such machine previously built.

Another obiect of the invention is to provide an automatic machine for lapping spiral bevel and hypoid gears in which the need for special and different cams for diiierent jobs is wholly eliminated, and in which a single cam of simple shape may be employed for lapping any pair of gears within the range of the machine.

Another object of the invention is to provide an automatic machine for lapping spiral bevel and hypoid gears in which the same part of the cam surface is used for producing the oscillatory motions of the carrier during both forward and reverse rotations of the gears, and the necessity for differently shaped cam portions for controlling the movements during rotation of the gears in opposite directions is avoided.

A further object of the invention is to provide an automatic machine in which the times for lapping of the opposite sides of the teeth of a pair of gears can be adjusted at will and in which the character of the lapping action on opposite sides of the teeth can also be varied at will to suit the particular gears which are to be lapped.

Another object of the invention is to provide an automatic machine for lapping spiral bevel and hypoid gears in which the use of change gears for controlling the character 01' the finishing operation is eliminated and in which quite simple con-J trols are employed instead for governing the amounts of the several motions which together eitect the lapping operation.

Still another object of the invention is to provide a lapping machine in which the several mothe carrier reciprocates and the angle through which it oscillates for any amount of reciprocation or the head may be varied. Thus, the

tions for lapping are derived from a single cam Y and in which, therefore, the structure of the machine may be very much simplified.

A still further object of the invention is to provide a machine of the character described in which simple, very eillcient means is provided for applying a brake-load 01' any desired amount to the gears during the lapping operation,

Still another object or the invention is to provide a machine on which all. types of spiral bevel and hypoid gears may be lapped regardless of whether they mesh with axes at acute, right, or obtuse angles.

Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims. a

In the machine of the present invention, the lapping motions are preferably applied to the pinion or drive member of the gear pair, which is to be lapped, instead of as in the conventional design to the gear or driven member. In the embodiment of the invention illustrated in the drawings, the drive spindle is .ioumaled in a carrier that is mounted in a head for oscillation and reciprocation about and in the direction of an axis oil'set from and parallel to the axis of the spindle, and the head is mounted in a column or upright for reciprocation in a direction perpendicular to the axis of oscillation of the carrier. The axial reciprocation of the carrier eil'ects lengthwise sliding of the teeth of one gear on the other; the oscillatory movement 01' the carrier varies the depth of engagement of the gears as they move lengthwise; and the reciprocatory movement of the head effects transverse movement of the gears relative to one another.

All of the motions are derived from a single cam. This cam reciprccates the head; and the carrier is so connected to the relatively stationary upright, on which the head slides, that as the head reciprocates it can both oscillate and reciprocate the can'ier. There are two rollers secured to the upright. One of these engages the straight guide surface of a block that is adjustable angularly about an axis extending at right angles to the axis of the carrier. The other of these engages the straight guide surface of a block that is adjustable angularly about an axis is inclined to the direction of reciprocation of the lengthwise, transverse, and depthwise movements or the gears can be varied relative to one another and the ratio of these movements can readily be changed to suit the requirements 01' any particular Job to be lapped.

The cam is oscillated to effect the reciprocation or the head. It may be provided with an operative surface of progressively increasin radius so that the greater the angle through which the cam is swung, the greater the distance through which the head is reciprocated. Adjustable stops carried by a control member, that is mounted on the same shaft with the cam, determine the angle through which the cam swings.

. There is one set of stops provided for controlling the angle ct oscillation of the cam during forward rotation of the gears, that are to be lapped, and there is a second set 01' stops provided 101' controlling the angle of oscillation of the cam during reverse rotation of the gears. Since the angle of. oscillation of the cam determines the extent of the reciprocation of the head, and since the angles of adjustment of the guideblocks determine the extent oi! the oscillatory and reciprocatory movements of the carrier for a given amount of movement of the head, it will be obvious that a single cam can be used for controlling the extent of the motions of the machine for lapping any pair of gears within the range of the machine.

head, axial movement is imparted to the carrier as the roller rolls along the straight guide surface of the block through reciprocation of the head. When the guide surface of the second block is inclined to the direction of reciprocation of the head, swinging movement is imparted to the carrier as the roller rolls along the straight guide surface of the second block in the reciprocation of the head. By adjusting the blocks, the angles of inclination of their guide surfaces to the direction of reciprocation of the head may be varied. Thereby the distance through which The rates of the motions are controlled electrically. Through suitable electrical controls, also,

them to be moved back and forth a plurality of' times during rotation of the gears in the reverse direction, and then stop the machine.

The mounting of the drive member on the head to which the lapping motions are imparted, enables the gear or driven spindle to be mounted in a head which may be adjusted angularly to incline its axis at any desired angle to the axis of the drive spindle, thereby permitting tapered gears that mesh with axes at right angles or at other than right/ angles to be lapped without inordinately increasing the amount oi floor space required for the machine.

In the drawings:

Fig. 1 is a plan view of a machine built according to one embodiment of this invention;

Fig. 2 is an end view, partly in section, of the drive head of the machine and its supporting column;

Fig. 3 is a transverse vertical sectional view through the drive head taken in a plane parallel to the view of Fig. 2 and on a somewhat enlarged scale, showing, also, a fragmentary section of the supporting column;

Fig. 4 is a longitudinal vertical sectional view through. the. drive head taken at right angles to the view of Fig. 3; I

Fig. 5 is a detail view showing one of the angularly adjustable blocks and rollers for controlling the oscillatory movement of the drive head;

Fig. 6 is a fragmentary view looking in the direction of the arrow 1 of Fig. 3, showing the cam,

which eiiects the lapping motions, and its folroller which. engages this block, the other roller,

and the supports for both rollers;

Fig. 7 is a fragmentary sectional view taken at right angles to the view of Fig. 6;

Fig. 8 is an enlargedview looking at the right hand end of the cam drive shaft shown in Fig. 2 and showing the control member, adjustable stops, and limit switches which govern the amount of oscillation of the cam shaft;

Fig. 9 is a fragmentary sectionalview showing the drive to the cam shaft;

Fig. 10 is an elevational view, with parts broken away, of the driven head of the machine;

Fig. 11 is a vertical sectional view through the driven head and driven spindle;

Figs. 12 to 17 inclusive are diagrammatic views illustrating the relative movements of the gear and pinion during lapping of a pair of gears on a machine constructed according to this invention; and

Fig. 18 is an electrical wiring diagram of the machine.

Referring to the drawings by numerals of reference, 20 indicates the bed or frame of the machine. Mounted on the bed or frame for sliding adjustment on ways 21, which are formed on the upper face of the bed. is a plate 22. Mounted on the plate 22 for angular adjustment thereon about an axis a: is a swinging base 24. The swinging base is secured in any adjusted position on the plate 22 by T-bolts 25 which engage in arouate T-slots 25 formed on the upper face of the plate 22 concentric of the axis X. Mounted on the swinging base 24 for rectilinear adjustment thereon along the ways 21, which are formed on the upper face of the swinging base, is the gear or driven head 28 of the machine. Adjustment of the head 28 on the base 21 may be effected by rotation of the shaft 45 (Fig. 10) which is journaled in the head. This shaft has a bevel gear 45 secured to its lower end that meshes with a bevel gear 41. screw-shaft 48 that is journaled in the head and that threads into a nut 49 that is fastened by bolts 52 to the sliding base 24. A graduated dial 56 with a knurled knob that is secured to upper end of shaft 45 permits the adjustment to be made precisely. The head 28 can be secured in any adjusted position on the sliding base by manipulation of the lever 43 which operates a suitable clamping device (not shown).

Mounted on the bed 20 for rectilinear adjustment thereon in a direction at right angles to the direction of adjustment of the plate 22 on the base is a column or upright 3|) which is adapted to slide in its adjustment on the ways 3| (Fig. 1) that are formed on the upper face of the bed. The adjustment is effected by rotation of the handwheel 29 which is secured to a screw-shaft (not shown) that is journaled in the bed and that threads into a nut (not shown) which is secured to the column 30. The column can be secured in any adjusted position on the ways 3i by manipulation of lever 53 (Fig. 2) whichserves to clamp the gib 54 against the underside of one of the ways 3|.

Mounted on the column 39 for vertical adjustment thereon is the drive head 32 of the machine. The adjustment of the drive head is effected by rotation of the screw shaft 34 (Fig. 3). This shaft is rotatably mounted in the column 39 on anti-friction bearings 35 and threads into a nut 35 that is secured in a plate 31. The plate 31 has a guide portion of dove-tailed shape, as shown in Fig. '1, which is adapted to fit into and This bevel gear is secured to a.

slide in a correspondingly shaped guide slot formed in the column 35. A tapered gib 55 and screw 55 serve to take up wear between the dovetailed guide portion and its way.

The drive head 32 is guided in its adjustment on the column 35 by the L-shaped ways 35 (Fig. 1). For the purpose of reducing friction to a minimum and of making this adjustment as smooth as possible, there are two sets of rollers mounted in the drive head 32 to engage and roll on the two ways 55 as the head is adjusted on the column. In each set of rollers, there is an upper and a lower roller 39 (Fig. 2) which engage the front face of a guide way 38, an upper and lower roller 40 which engage the rear face of the guide way, and an upper and lower roller 4| which engage one side face of the guideway, see 'Fig. 1. The adjustment of the head 32 on the column 30 may be made precisely throughuse of the knurled knob and graduated dial 42 which is secured to thescrew shaft 34. The several rollers 39, 45, and 4| are rotatably mounted on studs, such as the stud 44 shown in Fig. 4, which are secured m the head 32.

The mountings and adjustments of the heads 28 and 32 on the bed 20 of the machine are similar to those of the heads in the gear testing machine of the United States patent of Oliver F. Bauer, No. 1,909,088, issued May 16, 1933.

Mounted in the head 32 for oscillatory and reciprocatory movement therein is a carrier 59 (Figs. 2, 3, and 4). This carrier is mounted on a rod or bar 5| which is secured at its opposite ends in the drive head 32. The carrier is mounted on this bar by means of the sleeve bearings 53 and 54 so that it may not only swing about the bar but also have limited sliding movement to and fro along the bar. The bar has an enlarged head at one end which holds it against movement in the drive head 32 in one direction, and the nut 55, which is threaded to the bar, serves to hold the bar against movement relative to the drive head in the opposite direction.

Journaled in the carrier with its axis offset from but parallel to the bar 5| is the drive spindle 51 of the machine. This spindle is mounted in the carrier on anti-friction bearings 58 and 59. A labyrinth seal 59 is secured to the carrier at one end of the spindle 51 to prevent entry of dirt or grit into the bearings 59, while the bearing 58 is protected by the front wall of a cylinder 51, which is shown only .fragmentarily in Fig. 4, and which is secured to the opposite end of the carrier by screws 53.

The pinion or drive member P (Fig. 1) of the gear pair, which is to be lapped, is adapted to be secured to the drive spindle 51 by any suitable means as, for instance, by a clamp and draw bar (not shown). The cylinder 6| may form part of a conventional hydraulic chucking mechanism for securing the pinion to the spindle 51.

During operation of the machine, the drive spindle 51 is adapted to be driven first in one direction and then in the other from the motor 65. This motor is secured to the column 30 and drives the spindle 51 through a belt (not shown) and the pulley 55, the latter being keyed to the spindle 51.

During operation of the machine, also, the head 32 is moved up and down on the column 30. ,The reciprocatory movement of the head 32 is effected through operation of a motor 10 which is indicated diagrammatically in Fig. 18. This motor drives a shaft 1| (Fig. 9) which is Journaled on anti-friction bearings 12 and 13 in the column 30.

v7 I This shaft h'as-a worm (not shown) secured to or integral with it that meshes with a worm wheel '14 which is keyed to a shaft 18. The shaft 18 is journaled in the column 38 on anti-friction bearings 11 and 18 and has a worm 18 integral with it that meshes with a worm wheel 88 (Figs. 9 and 2) that is keyed to a shaft III. The shaft II is journaled in any suitable manner in the column 38 and is connected through universal joints and a stub shaft 83 with a shaft 84 (Figs. 2 and 3) that is suitably journaled in the plate 31.

Secured to the inner end of the shaft 84 is the cam 85 (Figs. 2, 3, and 6). A roller 88 rides on the periphery of this cam. \This roller is rotatably mounted upon a stud 81 that is secured to the head 32 by screws 88. The cam 85 may be formed as shown in Fig. 6, so that its peripheral surface is at a progressively varying distance from the axis of the shaft 84. Hence, as the shaft swings, the head 82 rises or falls depending upon the direction of movement of the shaft.

Pivotally mounted upon a pin 88 that projects forwardly from the plate 81 through a slot 88 in the head 32 (Figs. 6 and 7) is a link 8i. This link is pivotally connected by means of a pin 82 to a lever 84. The lever 84 is pivotally mounted at one end upon a pin 88 that is secured in a bracket 88. This bracket is fastened by means of screws 81 to the work head 32. The lever 84 carries a pin 88 at its free end. Upon this pin is rotatably mounted a roller 88 (Figs. 3, 6, and 7). The roller 89 is adapted to engage a straight slabbed-oif guide surface I88 formed on a block I 8 i This block is integral with a shaft I82 which is mounted in the carrier 58 for rotatable adjustment therein. The axis of this shaft extends at right angles to the axis of the spindle 51.

The angle of adjustment of the block I8I determines the amount of axial movement imparted to the drive spindle 51, that is, the amount of relative lengthwise movement between the teeth of the pinion P and the teeth of the mating gear G (Fig. 1), for as the drive head 32 rises and falls under actuation of the cam 85, the roller 88 will ride up and down on the guide surface I88 of the block ii. If this guide surface is vertical,

'that is, is parallel to the direction of movement of the head 32, no axial movement will be imparted to the spindle 51 and the carrier 58. If the guide surface I88 is inclined to the vertical, however. the carrier 58 and, with it, the spindle 51 will move back and forth as the work head rises and falls.

The amount of the back and forth movement will depend upon the angle of adjustment of the block I8l. Moreover, the direction of adjustment of the block angularly one side or other of the vertical will determine the direction of movement of the carrier and spindle for rise and fall of the head 32. Thus, for one angular p sition of the block IN, the carrier and work spindle will move inwardly as the head rises, while when the block is adjusted to the opposite angle, the carrier .and work spindle will move outwardly as the drive head rises. This permits of lapping gears whether the pinion is chucked in the usual fashion on the drive spindle with its apex extending forward of the spindle or is chucked backward with its apex extending toward the rear of the spindle. The angular position of the block I8I may be adjusted precisely through use of the micrometer dial I83 which is secured to the shaft I82 (Fig. 3).

A spring-pressed plunger I85 (Figs, 3 and 4), which is housed in the head 32, serves to constantly urge the carrier 58 and spindle 51 toward rearward position. This plunger which is actuated by the spring I88 engages one end of a lever I81 that is pivotally mounted at its opposite end by means of the pin I88 in the head 32. .The lever carries a pin I88 between its ends on which is mounted a roller I I8 that is adapted to engage a hardened block III which is secured in the carrier 58.

Fastened to the plate 31 by means of screws III is a bracket II8 (Figs. 3, 4, and 6). Journaled on anti-friction bearings H1 in this bracket is a cylinder H8 which is formed at opposite ends with roller portions H8 and I28. These rollers are adapted to engage, respectively, the straightsided projecting portions I2I and I22 of blocks I23 and I24, respectively. These blocks are mounted on arms 5 and I28, respectively. which are integral with and project from the carrier 58. The blocks are adjustable angularLv about aligned-axes which extend parallel to the axis of the drive spindle 51, and they may be adjusted angularly to incline the straight surfaces I2I and I22 at any desired angle to the vertical. Thereby the amount of swing oi the carrier 58 about the axis of shaft 5i may be adjusted to adjust the amount of depthwise in-and-out movement of the pinion P as the head 32 rises and falls under actuation of the cam 85. It will be obvious that if the blocks I23 and I24 are adjusted so that the surfaces I2I and I22 are vertical. then no swinging movement will be imparted to the carrier 58 about the bar 5I as the head 32 rises and falls, but if the surfaces I2I and I22 are inclined to the vertical, then as the head 32 rises and falls, the carrier will be oscillated about the axis of bar 5i and in-and-out depthwise movement will be imparted to the pinion. The direction of this movement for the rise of the head can be determined by the setting the guide surfaces I2I and I22 one side or other of the vertical. For precisely adjusting these guide surfaces, the blocks I23 and I24 are graduated as shown in Fig. 4 to read against zero index pointers carried by the arms I25 and I28, respectively.

For holding the guide surfaces I2I and I22 against the rollers H8 and I28, respectively, two spring-pressed plungers I3I and I32 (Fig. 3) are provided. These are housed in the head 32. The plunger I3I operates against a roller I33 which is rotatably mounted on a stud I35 that is secured in. one side of the carrier 58. The plunger I32 operates against the roller I34 that is rotatably mounted on a stud I38 that is secured in the opposite side of the carrier 58. The spring I 31, which actuates the plunger I3I, is more powerful than the spring, which actuates the plunger I32, and will ordinarily overcome the action of the latter spring.

When the blocks I23 and I 24 are in the positions shown in Fig. 4, the spring I31 overcomes the spring of the smaller plunger I32 and tends to holdthe guide surfaces I2! and I22 of the blocks against the rollers H9 and I28. When the blocks are reversed, however, the plunger I3I is locked down by rotating the lock-screw I38 which has a lock-pin I38 formed eccentrically on its inner end that engages in a recess I48 in one side of the plunger. Then the smaller plunger I32 is operable to urge the carrier 58 in the ,opposite direction to hold the guide surfaces I2I and I 22 against the rollers H9 and l28 The amount of the upand-down movement of the drive head 32 is governed from a control member I48 (Figs. 2-and 8) which is secured to the shaft 8 I. There are two pairs of stop plates secured to the rear face of the control member I40. The two members of one pair are denotedat IM and I42, respectively, while the two members of the other pair are designated at I43 and 144, respectively. Each of these members is adustable angularly about the axis of the shaft 8| and may be fastened in any adjusted position on the rear face of the control member I40 by a T-bolt I45 whose head engages in a circular T- slot I46 that is formed in the rear face of the member I40. The stop plates are locked in position by tightening the knurled nuts I46 which thread onto the T-bolts.

The stop plates have stop buttons I41, I48, I49, and I50, respectively, formed on their peripheral surfaces. The rear face of the control member is suitably graduated, as clearly shown in Fig. 8, to read against zero marks on the stop plates so that each pair of stop plates can be adjusted to space the stop buttons of that pair the desired distance apart.

The stop buttons I41 and I48 are adapted, during oscillation of the shaft 6|, to rock a lever I56 that is pivotally mounted by means of the stud Pivotal movement of the lever in this direction is limited by an adjustable stop I59 which is also carried by bracket I62. As the lever rocks about its pivot I51, it pushes in the plunger I60 to close the limit switch I6I. This limit switch is also carried by the bracket I62.

The buttons I49 and I50 are adapted to engage the nose I65 of a lever I68 which is pivoted by the stud I61 in the column 30. The lever I66 is constantly urged inwardly about its pivot pin I61 by a spring-pressed plunger I68 that is carried by a bracket I12 which is secured to the column 30. An adjustable stop-pin I69, which is also carried by" the bracket I12, serves to limit the inward movement of the lever I66. As the lever is rocked about its pivot against the resistance of the springpressed plunger I68 by engagement of one of the stop buttons I49 or I50 with the lug I65, the lever presses the plunger I10 of the limit switch I" inwardly to trip the limit switch. This limit switch is also carried by bracket I12.

The machine shown is wired, as will be described more particularly hereinafter, so that the shaft 8| and control member I40 are oscillated back and forth, being driven first in one direction and then in the other, the direction of rotation being reversed by tripping the limit switches I6I and "I. When the machine is started up, the limit switch I6I controls the direction of rotation of the control member I40 and shaft 8|, and each time that one or other of the buttons I41 or I48 strikes the nose I55 of the lever I56, the control member and shaft are reversed. Thus, at this stage of the operation, the amount of oscillation of shaft 8|, that is, the amount of movement of drive head 32, is controlled by the distance that stop-buttons I41 and I48 are set apart.

The machine illustrated is further so wired that after two complete oscillations of the shaft, the limit switch I6I is rendered inoperative and the limit switch I1I becomes operative. Then the oscillations of the shaft and control member are controlled by the stop buttons I49 and I50. Each time that one of these stop-buttons contacts the nose I65 of lever I66, the direction of rotation of the shaft M is reversed, and the amount of swing of shaft 8| and of movement of drive head 32 is controlled at this stage of the operation by the distance that buttons I49 and I50 are set apart. The machine illustrated is so wired further that after two complete oscillations of the shaft under control of buttons I 49 and I50, the limit switch I1I is rendered inoperative and themachine is stopped.

Safety stops are provided to stop the machine in case the stop-buttons I41 and I48 or I49 and I50 fail to function and fail to reverse the direction of rotation of the shaft. These safety devices are in the form of additional stop-buttons I13 and I14 which are provided on the periphery of the control member I40. These stop-buttons I13 and I14 are placed-diametrically opposite from one another, one between the stop plates HI and I43, and the other between the stop plates I42 and I44. These buttons I13 and I14 are adapted to engage with the V-shaped nose of a lever I18 (Fig. 2) which is pivotally mounted alongside the lever I66 on the stud I61. The lever I18 is constantly'urged toward the periphery of the control member I40 by a spring-pressed plunger similar to the plunger I68 and its movement may be limited in one direction through an adjustable stop pin similar to the stop pin I69. The lever I18 is adapted to actuate, when rocked, the limit switch I80, which is carried by the bracket I12. This limit switch is wired to stop the machine, when tripped, as will be described more particularly hereinafter.

Mounted on the periphery of the control member I40 at an angular position between the buttons I41 and I48 (see Fig.8) but in a position displaced axially from buttons I41 and I48 so as to clear the nose I55 of lever I56 is a button I82. This button is adapted to engage the tapered nose I15 of a lever I11 (Fig. 2) which is mounted alongside lever I56 to pivot about stud I51. The lever I11; when rocked, is adapted to trip a limit switch I19. On each swing of control member I40, whether under control of stop-buttons I41 and I48 or of stop-buttons I49 and I50, then, limit switch I19 will be tripped. The purpose of this limit switch will appear hereinafter.

The gear G, or driven member of the pair, which is to be lapped, is mounted on the spindle I (Figs. 10 and 11). This spindle is rotatably mounted in the driven head 28 of the machine on suitable anti-friction bearings 200 and 2M. The gear G may be secured to this spindle by any suitable means, for instance, by a draw bar I86 and a clamping disc (not shown). The draw bar is secured to a sleeve- I81 through the nuts I88 and a nipple I69, the latter threading into the sleeve. The draw bar is constantly urged toward workclamping position by a coil spring I90 which surrounds the sleeve I81 and which is interposed between the head of the sleeve and a nipple I84 that is keyed to spindle I85. The draw-bar is adapted to be moved to work-releasing position through application of fluid pressure to the rear end of a piston I83, which is housed within a cylinder I9I that is secured to head'28. Fluid under pressure menace 1 which it is desired to lap away, very simple means have been provided for taking up'the backlash and exerting-a moderate pressure be tween the gears throughout the whole lapping operation. For these purposes, a generator 205 is mounted in the driven head 28 to be driven from the driven spindle 135 through the pulleys 225 and 25V and the connecting belt 208. A rheostatiiid (Fi 18) of any suitable construction is provided for varying the resistance of the generator to adjust the brake load on the gears.

The machine of this invention, like the machine of the Bauer patent above mentioned, may he used for testing gears. ing gears, the various oscillating and reciprocatins motions of head 52 and carrier 52 are not employed, but the gears are simply run together under load. For applying a load to the gears during testing. a standard hand brake may be employed which may, as illustrated in Fig. 10, he in the term of a pair of brake-shoes 212 and tilt that are pivoted on the shaft 2 to engage When used for testl2 13in the positions which they occupy when the machine is stopped.

To put the machine in operation, the operator pushes in the normally-open start-button 255.

' arm 284 of the relay 252, the line 235, the coil 2%, and the line 255 to the main line In. When the coil 280 of controller 235 is energized, the

switch-arms 250, 2%, and 232 of the controller 235 are closed, thus closing the circuit to the main motor 55 from the main lines L1, Lo, and La through the lines 253,294, and 295 and starting this motor.

the periphery of a brake-drum 215 that is se-- cured to the spindle 185. The brake-shoes are constantly urged toward released position by coil-springs 2 I and 211. These springs surround the pin 218 and are interposed between the free ends of the brake-shoesand opposite faces of 9. lug .2l3 which is integral with or secured to the head 25. The hand-brake is adapted to be actuated by a hand lever 220 which is keyed to a shaft 221 that is iournaled in the head 28'. Keyed to the shaft 221, also, is a bell-crank 223. One arm of this bell crank is connected through a link 224 with an actuating member 225 that engages one of the brake shoes 212. The other arm of the bell-crank is engaged by a coil spring 225. This spring is interposed between this arm of the bell-crank and a lug 221 formed on a bracket 220' that is integral with or secured to the head 23. spring 225 serves to counterbalance lever 220. By pressing down on the lever be used advantageously not only in testing but also in lapping if a considerable amount of stock is required to be removed in lapping.

One way in which the machine may be wired to accomplish the purposes of the present invention is illustrated diagrammatically in Fig. 18. Here 235 denotes the controller for the main motor 55: 235 and 231 designate combination armature-field rheostats for controlling the speed of rotation of the oscillating motor during rotation in opposite directions of the gears that are to be lapped; 233 denotes an A. C.-D. C. rectiher for the field 233 of the oscillating motor 240 denotes an A. C.-D. C. rectifier for the armature 2 of the oscillating motor iii; 242 desighates an A. C.-D. C. rectifier for the generator 255; 243 the shunt field of the generator 205; 244 the armature of the generator; and 245 the load resistor for the generator. The motors 65 and I0, and the generator 205 may be of standard construction. The parts 235, 236, 235, 240, 231, 242, 210 and 245 may also be standard parts of any suitable structure. The machine is provided with a plurality of relays 250, 2:, 252, 253, and 254. The relay 254 is a ratchet relay. All

of these relays may be of any standard or suitable structure. The machine is also provided with standard start and stop-buttons 255 and 251, respectively. The parts are shown in Fig.

When the starting button is closed, the oscillating motor is also started. This is aifected by energizing the coil 300 of the controller 245. The circuit to the coil 300 is-made from the main line L]. throught the lines 250 and 251, the limit switch I30, the line 252, the stop-button 251, the line 253, the start button 255, the lines 254, "I, and 302, the switch arm 303 of the relay 251, the line 304, the coil 300 and the lines 355 and 215 to the main line L2. The energizing oi the coil 500 closes the switch arms 305 and 301 of the controller 245 making a circuit to the armature 241 of the oscillating motor from the main line Li through the lines 3i0and 311, the rectifier 240, the line 3i2, switch arm 305, line 313, the armature 2", the line 314,-the switch arm 301, the line M5, the rectifier 240 and the lines 315 and 210 to the main line L2. The circuit to. the shunt field 239 of the oscillating motor 10 is always closed, when the machine is in operation, from the main line L1 through the lines 3l0 and 311, the rectifier 238, the line 315, the shunt winding 233, the line 3l3, the rectifier 235, and the lines 320 and 210 to the mainline 12. Thus,

- the motor 10 is started.

When the start button 255 is closed, a circuit is also closed from the main line L1 through thelines 250 and 251, the normally-closed limit switch 150 (Figs. 8 and 2) the line 252, the normally-closed stop button 251, the line 253, the start button 255, the line 254, the movable switch arm 255 of the ratchet relay 254 and the number one station of this relay, the line. 255, the coil 251 i511, line 252, stop-button 251, line 253, start-button 255, lines 254 and 214, switch-arm 2" of relay 253, line 215, coll 215 of relay 255, and lines 259 and 210 to main line L2, thus energizing the coil 215 of the relay 250, closing the switch-arm 211 and opening the switch arm 215 of this relay.

With the main motor 55 running, the gears P and G, which are to be lapped, rotate in engagement, and with the oscillating motor 10 running, the shaft 8| and cam 55 are oscillated to move the head 32, to swing and reciprocate the carrier 50. As the shaft 5| swings in one direction from starting position, the button 152 (Fig. 8) may strike the nose of the lever 111 (Fig; 2), closing the limit switch I13, (Figs. 2 and 18). At this stage, however, the closing of limit switch I18 does not effect any action. As the shaft 8! swings on, though, the button I41 striks the nose I58 of the lever I56, closing the limit switch I6I. This energizes the coil 325 of the ratchet-relay 254, the circuit to this coil being made from the main line L1 through the lines 260 and 326, the now-closed limit switch I6! the line 321, the switch-arm 328 of relay 252, the lines 330 and 33!, the coil 325, and the lines 332 and 210 to the main line L2. When the coil 325 is energized, the switch-arm 265 is advanced from station 1 to station 2 of the ratchet relay 254. v

The shift of the switch-arm 265 causes the coil 335 of the relay 25! to be energized, the circuit to this coil being made from the main line L1 through the lines 260 and 26!, the limit switch I80, line 262, the stop button 251, the lines 336 and 331, the now-closed switch-arm 211 of the relay 250, the lines 338 and 264, the switch-arm 265 of ratchet relay 254, No. 2 station of that relay, the line 338, the coil 335, and the lines 343, I

266 and 210 to the main line La.

The energizing of the coil 335 causes the switch-arm 306 to be closed and the switch-arm 303 to be opened. The opening of the switcharm 303 breaks the circuit to the coil 300 of the controller 246 and stops the forward rotation of the oscillating motor 10. The closing of the' switch-arm 306 makes a circuit to the coil 340 of this controller, causing the motor to be driven in reverse. The circuit to the coil 340 is from the main line L1 through the lines 260 and 26!, the limit switch I80, the line 262, the stop-button 251, the lines 336 and 331, the switcharm 211 of relay 250, the lines 338, 264, and 30!, the switch-arm 306 of relay 25!, the line 34!, the coil 340, and the lines 342 and 210 to the main line L2. The energizing of the coil 340 causes switch- arms 346 and 341 of controller 246 to be closed, closing the reversing circuit to the armature 24! of motor 10, this circuit being made from the rectifier 240 through the lines 348 and 349, the switch arms 346 and 341, the lines 350 and 35! and the lines3I-4 and 3I3.

The shaft 8! is now driven in the reverse direction, causing the direction of movements of the head 32 and carrier '50 to be reversed. The shaft 8! and controller I40 now rotate in a com-- ter-clockwise direction as viewed from the rear (Fig. 8).

When the button I-82 passes under the nose I of the lever I11, the limit-switch I19 is closed but nothing happens. When the 'button I48 contacts the nose I58 of the lever I56, however, the limit-switch I6! is closed. This again causes a circuit to be made to the coil 325 of the ratchet relay 254 in the manner already described and this coil is again energized. The switch-arm 265 is; therefore, moved from station No. 2 to station No. 3 of the relay. This causes the circuit to the coil 335 of the relay to be broken, causing the switch-arm 306 todrop out of engagement, disconnecting the lines and 34!, and causing the switch-arm 303 to move into engagement, connecting the lines 302 and 304.

The dropping of the switch-arm 306 out of engagement breaks the circuit to the coil 340 of the controller 246 while the closing of the switcharm 303 makes the circuit to the coil 300 of this controller. Thus the oscillating motor 10 is again reversed to cause it again to drive in the forward direction. Again the shaft 8! swings clockwise between the limit set by the stop-buttons I4! and I40 and during this counter-clockwise movement, the button I82 again trips the lever I11 and the limit-switch I18 without eflecting any operation. At the end of the clockwise movement, the button I48 again strikes the nose I of the lever I56, again closing the limit-switch I8! and again energizing the coil 325 of the ratchet relay 254 to again shift the switch-arm 285.

This time the switch-arm moves from station No. 3 to station No. 4 of relay 254. This again causes the coil 335 of relay 25! to be energized, the circuit to this coil being made from the main line Lrthrough the lines 260 and 26!, the limitswitch I80, the line 262, the stop-button 251, the line 336, the line 331, the switch-arm 211, the line 338, the line 264, the switch-arm 265. station No. 4 of relay 254, the line 355, the line 338, the coil 335, and the lines 343, 268, and 210 to the line L2.

The energizing of the coil 335 again closes the switch-arm 306 and opens the switch-arm 303, causing the oscillating motor 10 to be again reversed as already described. Then the shaft 8! and control member I40 move in a counter-clockwise direction and again the button I 82 rides idly over the nose I15 of the lever I11 and again when Y the button I48 strikes the nose of the lever I55, the limit-switch I6! is closed. This again causes the coil 325 to be energized, advancing the switcharm 265' to station No. 5. This breaks the circuit to the coil 335, allowing the switch-arm 305 of the relay 25! to open and the switch-arm 303 of this relay to close.

This again reverses the oscillating motor 10 and shaft 8!. On this swing of the control member I40, however, when the button I82 rides over the nose I15 of the lever I11, closing the limit-switch I19, a circuit is made to the coil 360 of relay 252. This circuit is from the main line L1 through the lines 260 and 26!, the limit-switch I80, the line 262, the stop-button 251, the lines 336 and 331, the switch-arm 211 of relay 250, the lines 338 and 264, theswitch-arm 265 of relay 254, the line 36!,

- the coil 360 of relay 252, the line 362, the nowclosed limit-switch I16, and the lines 363 and the line 210 to the main line L2.

The energizing of the coil 360 of relay 252 causes the switch-arm 283 to be closed and the switch-arm 284 to be opened. When the switcharm 284 is opened, the circuit to the coil 280 of the controller 235 is broken, stopping the forward rotation of the main motor 65. When the switch arm 283 is closed, a circuit is made to the coil 355 of the controller 235, starting the main motor 65 in reverse. The circuit to the coil 365 is from the main line L1 through the lines 260 and 26!, the limit-switch I80, the line 262, the stop-button 251, the lines 336 and 331, the switc'h arm 211 of relay 250, the line 330, the line 264, the line 28!, the switch-arm 283 of relay 252, the line 366, the coil 365, and the line 286 to the main line Le. The energizing of the coil 365 closes-th switch- arms 310, 31!, and 312, closing the reverse circuit to the motor 65 from the main line L1 through the lines 3I0, 361, switch-arm 310 and lines 368 and 284; from the main line La through the lines 218 and 368, switch-arm 31! and lines 313 and 283: and from the line Lc through the line 314, the switch-arm 312, and lines 315 and 285. The main motor 65 now drives the gears P and G in reverse.

At the same time that the energized 'coil 360 closes the switch-arm 283 and opens the switcharm 284 of relay 252, it closes the switch-arm 328 and opens the switch-arm 328 of this relay. This i r puts the limit-switch ill in the control circuit and cuts out the limit-switch IN. This means that the buttons I48 and I58 (Fig. 8) now con-' trol the limit of movement oi the controller I48 and of shaft 8!. The shaft 8i now oscillates for the distance determined by the settings of the buttons its and its. During each swing. the button E82 closes the limit-switch G18 as before, and, as before, at the end of each swing, one or other of the buttons i188 and-W8 closes the limitswitch ili.

When the limit switch i1!) is closed, a circuit is made to the coil 828 of the ratchet relay 288. This circuit is from the main line Li through the line 288, the limit-switch ili, the line 888, the now-closed switch-arm 828 of relay 282. the line 881. the coil 325, and the lines 882 and 218 to the main line L2.

This energizes the coil 828 and advances the switch-arm 285 of the ratchet relay 288 from station No. 5 of the relay to station No. 6. This causes the cell 385 of relay 256 to be energized, the circuit to this coil being made from the main line Ll through the iines 288 and 281, limitswitch 188, the line 282, the stop-button 251, the 0 lines 338 and 831, the switch-arm 211 of the relay 288, the lines 888 and 284, the switch-arm 285, the lines 882 and 339, the coil 335, and the lines 848, 269, and 218 to the main line L2. This closes the switch-arm 386 and opens the switcharm 383 of the relay I, reversing the oscillating motor 18 in the manner already described.

When the limit-switch MI is closed again at the end of the new reverse swing of control member 148 and shaft 8i. the coil 825 is again energized to shift the switch-arm 265 of ratchet relay 254 to station No. '1. This breaks the circuit to the coil 335 and again reverses the oscillating motor 18 and with it the direction of swing of control member 148 and shaft 8I.

When the limit-switch IN is closed once more at the end of the new swing of control member 148 and shaft 8|, the coil 335 is again energized through the connection of station No. 8 of ratchet relay 254 with line 338. This again reverses the oscillating motor 18, shaft 8i, and control member I48, When the limit-switch I1I is again closed at the end of this new swing of shaft 8i and control member I48, the coil325 is again energized to advance the switch-arm 265 to station No. 9 of the ratchet relay 254. This again reverses the oscillating motor 18, again causing rerfllzrsal of swing of shaft 81 and control member When the button 182 closes the limit-switch 119, on this swing of shaft 8i and control member M8, the coil 385 of the relay 253 is energized. The circuit to this coil is made from the line Ll through the lines 268 and 26I, the limit-switch N8, the line 262, the stop-button 251, the lines 338 and 331, the switch-arm 211 of relay 258, the lines 338 and 264, switch-arm 285 of ratchet relay 254, station No. 9 ofrelay 254, the line 386, coil 385 of relay 253, the lines 381 and 362, limit- ,swltch I19, and lines 363 and 218 to the main line This causes the switch-arm 212 of relay 253 to be closed and switch arm 21I of this relay to be opened. The opening of the switch-arm 21I breaks the circuit to the coil 216 of the relay 258. This allows the switch-arm 211 of relay 258 to open and the switch-arm 218 of this relay to close.

When the switch arm 218 is closed, the coil 395 of relay 252 is energized to reset the switcharms 283, 284, 329, and 328 of this relay to the accesses l6 positions shown in Fig. 18. The circuit to the coil 885 is made from the main line L1 through the lines 268 and 26I, the limit-switch I88, the line 262, the stop-button 251, the line 238, the switch arm 218 of relay 258, the line 38I, the switch-arm 212 of relay 253, the line 386, the coil 385, and the lines 381, 269 and 218 to the main line In.

The closing of the switch arms 212 and 218 also makes a circuit to the coil 888 of ratchet relay 268. This circuit is from the main line in through the lines 268 and 26B, the limit-switch 188, the line 262, the stop-button 251, the line 88, the switch-arm 218, the line 881, the switcha-rm 212, the line 892, the coil 888, and the lines 382 and 218 to the main line L1. When the coil 888 is thus energized, the switch-arm 285 is reset from station No.-9 back to station No. l.

When the switch-arm 811 of the relay 288 is opened, the hold-in circuit to the coil 288 of controller 235 is broken, and the circuits to the coils 888 and 388 of controller 288 are also opened. Hence, the main drive motor and the oscillating motor 18 are stopped, stopping the machine. The operation of lapping the pair of gears is complete, and the gears may be removed from the machine and a new pair chucked thereon. To restart the machine, it is again necessary to press in the start-button 256.

It is to be noted regarding the above-described circuit that, if the power should fail and the machine stop before the lapping operatlon is completed, the switch-arm 265 of ratchet relay 254 will not be reset. When the machine is started formed will not be repeated, but the switch-arm 265 will simply remain at whatever station it has reached-when the power is cut off, and when the power is restored again, the machine will resume its operations from the point where it was stopped. The switch-arm 256 can only be reset when it has reached No. 9 station of the ratchet relay 254, that is, when it has reached the position where the lapping operations on the pair of gears have been completed.

As already stated, if one of the stop-buttons 181, I48, 149. or I58 should fail for any reason to trip the limit switch i6I or ill to reverse the direction of swing of shaft 8i, then the button 113 or l14 will open the normally-closed limitswitch 188. This will break the circuits to the motors 65 and 18 and stop the machine.

In order to obtain the'desired tooth hearing or contact on opposite sides' of the teeth of a pair of spiral bevel or hypoid gears, it has been demonstrated that it is desirable to run the meshing gears together first in one direction and then in the other and that during rotation in opposite directions, the gears should be moved through different angles and at different rates. The adjustable stops MI, I42, I43, and I44 allow moving the gears through different angles. The different rates are obtained by adjustment of the rheostats 236 and 231 which control the shunt field and armature voltages of the motor 18 and hence its speed of rotation during forward and reverse drives, respectively. The two rheostats are connected together through the lines 488 and MN. The lines 488 and 48I serve, also, to connect the two rheostats to the rectifier 248. The two rheostats are connected to the rectifier 238 through the lines 482 and 483. The rheostat 236 is connected to the line 285 by the line 484, while the rheostat 231 is connected to the line 386 by the line 485. Thus, the rheostat 236 is wired to control the speed of the motor 18 during forward rotation of the gears being lapped under actuation of motor 65, while the rheostat 251 is wired to control the speed, of the motor I during the re-.

verse rotation ,of the gears.

As already stated, the load on the gears during lapping may be varied by adjustment of the of course, that during operation of the machine,

a suitable lapping compound is applied to the gears by means known in the art. After the various adjustments have been made to bring the gears to be lapped into meshing engagement; the several rheostats have been set to control the speed of the oscillating motor-during forward and reverse rotation of the gears and to control the load on the gears; the stops I 4|, I42, I45, and I44 have been adjusted to control the angle through which the control member I40, shaft 8| and cam 85 are oscillated during forward and reverse rotation of the gears; and the blocks IIII (Fig. 3), I23 and I24 (Fig. 4) have been adjusted to determine the amounts of axial and oscillatory movements of carrier 50 and spindle 51 for the up and down movement of head 52; the operator starts the machine by pressing in start button 256. Then the gears are driven in mesh by motor 65 and the head 32 is moved up and down, and the carrier 50 ismoved back and forth and swung from side to side through operation of the motor III. The cam shaft 8| is rotated. by motor III in one direction until one of the buttons I41 or I48 strikes the lever I56 to close the limit-switch I6I. Then the motor I is reversed, and head 32 and carrier 50 are moved in the opposite direction. Two complete forward and reverse swings of the cam shaft III, that is, two complete up and down movements of the head 32, oscillations of carrier '50, and reciprocations of carrier 50 are effected. Then, when the switch-arm 265 of relay 254 reaches station No. 5 of that relay, the limit-switch IBI is rendered ineffective and the limit-switch III is made effective. Then the motor 55 is reversed, reversing the direction of rotation of the gears being lapped. Then the shaft 8| is swung back and forth through the distance determined by stops I49 and I50. Two full up-and-down movements of the head 32, two full oscillations and two full reciprocations of the carrier 51 are made. Then the switch-arm 265 reaches station No. 9 of the ratchet relay 254, and the lapping is completed.

Figs. 12 to 17 inclusive illustrate diagrammatically the motions of the machine in the lapping of a pair of spiral bevel or hypoid gears P and G. The gears shown are of left-hand spiral curvature, and they are constructed to have the usual amount of tooth surface mismatch or localization of tooth bearing, the side surfaces 4" and 8 of a tooth space of the gear contacting at a central area along the sides with the mating side surfaces 9 and 420, respectively, of a tooth of the pinion.

Figs. 12 and 13 show the gear G and pinion P in mesh in correct running position with their aplces H5 and 41-6 coinciding. As the carrier 50 moves rectilinearly in one direction, moving the piniontoward the large end or heel of the gear teeth, the head 52 is simultaneously moveddow'n, and the carrier 50 is swung outwardly. Thus, as shown in Figs. 14 and 15, the apex 4|! of the pinion is displaced downwardly and outwardly from the apex 4| 5 of the gear, and simultaneously the pinion is withdrawn axially to prevent interference between the gear and-pinion teeth and to maintain the backlash constant. When the carrier 50 moves rectilinearly in the opposite direction, the head 32 is simultaneously moved up. and the carrier 56 swung first inwardly and then outwardly again. Thus, the pinion moves through the position shown in Figs. 12 and 13 to the position shown in Figs. 16 and 17. In this last position, the apex 4I5 of the pinion is displaced upwardly and inwardly with reference to the apex 5 of the gear. Thus, the tooth surfaces of gear and pinion slide over one another and eflfect the lapping operation.

While the invention has been described particularly with reference to a machine for lapping gears, it will be understood that essentially the same structure may be used in a machine for burnishing gears, as will be obvious from the art. It will further be understood that, while the invention has been described in connection with a machine for finishing gears, certain features are capable of general application. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the

principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

Having thus described our invention, what we claim is:

1. In a machine for finishing tapered gears. a pair of rotatable spindleswhose axes are angularly disposed to one another, means for detachably securing a gear to each of said spindles. means for adjusting the gears into mesh, means for driving one of the spindles to drive the other spindle by the meshing engagement of the gears, means for reciprocating the drive spindle axially to move the gear carried thereby lengthwise of the teeth of the other gear, and means for reciprocating one of said spindles in time with the first named reciprocating movement ina direction at right angles to the axis of the drive spindle to'efiect relative movement between the gears in a direction transverse of their teeth.

2. In a machine for finishing tapered gears, a pair of rotatable spindles whose axes are angularly disposed to one another, means for detach,- ably securing a gear to each of said spindles, means for adjusting the gears into mesh, means for driving one of the spindles to drive the other spindle by the meshing engagement of the gears.

- means for reciprocating the drive spindle axially 19. a said gears as their teeth move longitudinally and transversely of one another.

3. In a machine for finishing tapered gears, means for supporting a pair. of gears .to run together in mesh with angularly disposed axes, means for rotating one of the gears to eflect rotation of the pair through their intermeshing' engagement, means for effecting rela'tive move ment between the gears in a direction lengthwise of their teeth during their rotation, means for simultaneously eiiecting relative movement be-.

tween the gears transversely of their teeth, and means for adjusting one of said two last named means to adjust the amount of one of said movements independently of the other.

4. In a machine for finishing tapered gears, means for supporting a pair of gears to run together in mesh with angularly disposed axes, means for rotating the gears together, means for efiecting relative movement between the gears lengthwise of their teeth during their rotation, means for simultaneously eifecting relative movement between the gears transversely of their teeth, means for simultaneously eifecting relative movement between the gears in the direction of tooth depth, and means for adjusting at least two of the last three named means .to adjust the amounts of said relative movements with respect to one another.

5. In a machine for finishing tapered gears, means for supporting a pair of gears to run together in mesh with angularly disposed axes, means for rotating one of the gears to eifect rotation of the pair through their intermeshing engagement, said gears being mounted for relative movements lengthwise, transversely, and depthwise of their teeth, means for effecting one of said movements, and means. operable on said movement to effect simultaneously and in time -therewith the other two movements, said last named means being adjustable to vary the ratio of the three movements relative to one another.

6. In a machine for finishing tapered gears, means for supporting a pair of gears to run together ,in mesh, means for rotating the gears first in one direction and then in the other, means for eifecting a plurality of reciprocaitory movements between the gears lengthwise of their teeth and a plurality of reciprocatory movements transversely of their teeth during rotation of the gears in each direction, and means for adjusting the amount and speed of the reciprocatory movements during rotation of the gears in on. direction independently of the amount and speed of the reciprocating movement during rotation of the gears in the opposite direction.

7. In a machine for finishing gears, a pair of spindles for supporting a pair of gears to run together in mesh, means for rotating the spindles first in one direction and then in the other, a support in which one of the spindles is journaled, a cam, a follower engaging said cam and secured to said support, means for oscillating the cam to efifect reciprocation of the support during rotation of the-spindles, adjustable means for limiting the amount of oscillation of the cam during rotation of the spindles in the forward direction, and separately adjustable means for limiting the angle of oscillation of the cam durin rotation of the spindles in the reverse direction.

8. In a machine for finishing gears, a pair of spindles for supporting a pair of gears to run together in mesh, means for rotating the spindles first in one direction and then in the other, a support in which one of the spindles is journaled.

dles in both the forward and reverse directions.

an oscillatory cam for reciprocating said support, means for oscillating said cam, means for reversing the direction of rotation of the spindies after a predetermined number of oscillations of the cam, and separate means for determining the rates of oscillation and angles through which the cam is oscillated during rotation of the spin- 9. In a machine for finishing gears, a support,

a head reciprocally mounted on the support, a

carrier movably mounted in the head, a spindle journaled in .the carrier, a second spindle journaled in the support, said spindles being adapted to carry a pair of gears, an oscillatory cam for reciprocating the head, means for oscillating the cam, and a block and follower, one of which is secured to the carrier and the other to the support, said block having a guide'surface on which the follower rides during movement of the head to impart movement to the carrier on movement of the head, said block being adjustable angularly to incline its guide surface to the direction of reciprocation of the head.

10. In a machine for finishing gears, a pair of spindles-means for securing a gear to each of the spindles, a support, a head reciprocally mounted on the support, a carrier in which one of the spindles is journaled, said carrier being' mounted on the head for oscillation about an axis parallel to the axis of said spindle and for reciprocation in the direction of said axis, means for reciprocating the head, two control devices each of which comprises a block and follower, one of which is secured to the carrier and the other of which is secured to the support, each of the blocks having a straight guide surface on which the follower rides during reciprocation of the head, one of the blocks being adjustable about an axis extending in the direction of the axis of oscillation of the carrier and the other of the blocks being adjustable about an axis extending at right angles to the axis of oscillation of the carrier, and means for rotating the spindles first in one direction and then in the other.

11. In a machine for finishing tapered gears, a pair of spindles that are angularly disposed to one another, means for detachably securing a gear to each of said spindles, means for adjusting the spindles relative to one another to bring the gears into mesh, means for rotating the spindles first in one direction and then in the other to rotate the gears in mesh, an oscillatory cam for eifecting relative reciprocatory movements between the gears while they are rotating, separately adjustable means for controlling the angle through which the cam is oscillated and the speed at which it is oscillated during rotation of the spindles in the opposite directions, and means actuated by said reciprocatory movements for eflecting further relative reciprocatory movements between the gears in a direction inclined to the first named reciprocatory movements.

, 12. In a machine tool, a rotary spindle, an electric motor for driving said spindle in both directions, separately adjustable means for controlling the speed of rotation of the motor during forward and reverse rotations of the spindle, respectively, an oscillatory control member, and means

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