US2247795A - Electric hoist - Google Patents

Description

y 1- P. WHITCOMB ETAL 2,247,795

ELECTRIC HOIST Filed Feb. 1, 1958 6 Sheets-Sheet 1 INVENTORS a Pres ton Nfu' {comb Georg? F1 atchell ATTORN EYS u y 1, 19 1- P. WHITCOMB EIAL 2,247,795

ELECTRIC HOIST Filed Feb. 1, 1958 6 Sheets-Sheet 2 INVENTORS a??? Alf/i es" 7 ear C ATTORNEYS July 1, 1941. p WHITCQMB ETAL 2,247,795

ELECTRIC HO IS T Filed Feb. 1, 1938 6 Sheets-Sheet 3 INVENTOK Pres ion Whize ii ii b Georg e H. Nit ell ATTORNEYS y i, 1941. P. WHMQMB Em 2 247,795

ELECTRIC K0151 I Filed Feb. 1, "i938 s Sheets-Sheet 4 u Zea l i 3 1N VENTORS w 3 Pres Zon Whdfcomb BY George H. Milo/(e11 (29 (L5, 30m s 1 1941- P. WHITCOMB, ETAL 2,247,795

ELECTRIC HOIST Filed Feb. 1, 1938 6 Sheets-Sheet 5 I July 1, 1941. P. WHITCOMB ETAL ELECTRIC HOIST Filed Feb. 1, 1938 6 Sheets-Sheet 6 0 0 m m h v M na ny Patented July 1, 1941 UNITED STATES PATENT OFFICE ELECTRIC HOIST Preston Whitcomb, Kenmore, N. Y., and George A. Mitchell, Muskegon, Mich, assignors to Manning, Maxwell & Moore, 1110., New York, N. Y., a corporation of New Jersey Application February 1, 1938, Serial No. 188,044

7 Claims.

in the hoist and not on the remainder thereof.- A further object of this invention is to in-.

clude in such, a combination a compensating sheave attached to the hoist mounting thereby removing one-half of the loads lifted by the hoist from the hoist proper.

Another object of the invention is to provide a hoist having a hoist drum within which the driving motor is mounted and connected thereto by means of a compact gear train.

Another object of the invention is to provide a supporting mounting having an adjustable roller assembly by means of which the entire structure may be supported from overhead by I-beams and transported therealong.

Another object of the invention is to provide cable guiding means for ensuring the proper movement of the cable onto and off of the cable drum.

A still further object of the invention is to,

provide a brake for the hoist which acts at all times to hold the hoist against downward movement of the hook under load and which is automatically actuated when the motor is de-energized thereby ensuring at all times against undesired descent of the load.

A further object of the invention is to provide automatically acting means to de-energize the motor at the limit of movement in the upward direction.

These and many other objects as will appear from the following detailed disclosure of one embodiment of the invention are successfully secured.

This invention resides substantially in the combination, construction, arrangement and relative location of parts, all as will be described in greater detail in the following specification.

In the accompanying drawings,

Figure 1 is a front perspective view of an elec-' tric hoist constructed in accordance with this invention; I

Figure 2 is a similar view from the rear;

of bars 2 and 3.

Figure 3 is a right hand end elevational view thereof, see line 33, Figure 6;

Figure 4 is a left hand end elevational view thereof, see line 44, Figure 6;

Figure 5 is a top plan view thereof;

Figure 6 is a vertical, central, longitudinal, cross-sectional view showing the internal mechanism;

Figure '7 is a cross-sectional view taken on the line 1-1 of Figure 6;

Figure 8 is a cross-sectional view taken on the line 88 of Figure 6;

- Figure 9 is a cross-sectional view taken on the line 89 of Figure 6;

Figure 10 is a cross-sectional view taken on the line I0-i0 of Figure 6; I

Figure 11 is a cross-sectional view taken on the line ll-Il of Fig. 6; v

Figure 12 is a cross-sectional view taken on the line 12-12 of Figure 6; and

Figure 13 is a cross-sectional view taken on the line l3-l3 of Figure 6.

The supporting mounting includes an end plate I of circular form having bolted or otherwise secured to the outer face thereof a pair Spaced therefrom, as is clear, for example, from Figure 6, is a second end plate or disc 4 having bolted to the outer face thereof a pair of bars 5 and 6. Encircling these discs and forming therewith a closed housing is a cylindrical casing C which with the disc forms, as is clear from Figure 6, a suitable housing for the cable drum within which is enclosed the driving motor and the gear train. The casing C projects beyond the disc 4 and is closed at its outer end by a cover plate I9 forming a housing for the brush and brake assemblies.

As is clear from Figures 1 and 2, the bars 5 and 6 extend through slits in the casing C. A series of cross-bracing bars 2 and 3" interconnect the bars 2, 3, 5 and 6. Also extending between the bars}, 3, 5 and 6 are a pair of tubes l2 and I3 which have mounted therein cylindrical plugs of which two are shown at I and 8, see Figures 5 and 7. These plugs are secured in the ends of the tubes in any suitable manner and are provided with ends of reduced diameter, on each of which ism'ounted a metal washer H, a resilient washer H, and a cylindrical resilient sleeve 9. The sleeves 9 are mounted in metallic sleeves III which in turn are mounted and secured by welding in the ends of the bars 2, 3, 5 and 8. Thus the tubes l2 and I3 are interconnected with the supporting mounting through vibration absorbing bushing structures, one of which is fully illustrated in cross-section in Figure 5.

A pair of metal plates l5, the configuration of which may be seen from Figures 3 and 4, are provided with aligned openings in which are welded short metal sleeves l5 of an internal diameter to ensure a smooth sliding fit on the tubes l2 and I3. Rotat-ably mounted on these plates in aligned pairs are rollers i1 which are preferably so formed a to ride smoothly on the flanges of an I-beam, as indicated at B in Figures 1 and 2. Extending through and between these plates is a rod i8 reversely threaded at opposite ends and engaging threaded nuts secured to the plates as shown in Figure 5. The left hand end of this rod is provided with a headed end i3 and a spaced collar so as to engage therebetween the notched end of a lug 23 fixed to the end plate i. When a suitable tool is applied to the nut I3 the l'od l8 may be rotated while held against longitudinal movement, thereby causing movement of the plates towards and away from each other. By this arrangement it is possible to effect the proper spacing between the rollers H to permit of mounting of the hoist on an overhead support such as an I-beam and the adjustment of the rollers for smooth movement therealong. Within the casing formed by the discs I and 4 and the casing C is the cable drum which includes the end discs 2i and 22 and the cylindrical casing 23 suitably grooved on its surface to receive the cable. The discs 2| and 22 and the cylinder 23 are united together into a rigid structure and are joumaled on the bearings 24 which are supported on the discs I and 4. As is clear from Figure 6, the drum 23 is counterbored to form a shoulder against which the motor field laminations 25 rest. These laminations are secured against the shoulder by means of a sleeve 21 which is forced into the drum 23 and up against the laminations. At 25 are diagrammatically illustrated the field windings.

Secured within the drum and against the flanged edge of the sleeve 21 is a cup-shaped disc 28 which is secured within the drum by means of screws 23. The cup rim has formed thereon the internal gear 33, see Figure 6. A somewhat similarly shaped cup member 3i is provided on the inner periphery of its rim with an internal gear 32 and on its outer opposite face with a hub which sets in the disc i and is secured therein and held against rotation by means of a key 33. This hub is also engaged by means of a short threaded plug 53 to which is applied a nut 4|, by means of which it may be securely locked against longitudnal movement. At 34 is the armature shaft of the motor. A sleeve 34' on the shaft is provided with a squirrel-cage armature 35 having cooling fan blades 35. The shaft 34 revolves in the bearing 38 in member 3| and is supported on bearing 31 through member 54 secured on its end. The shaft is free to 'turn in disc 4 since the cable drum also revolves on shaft 34 at its reduced por-- tion 34'. Since the member 23 rotates with the drum a bearing 42 therefor is provided on the shaft 34. Secured to the shaft 34 is an eccentric sleeve 43 upon which are mounted a pair of bearings 44 providing a rotatable support for the double-toothed pinion 45. One set of teeth thereof meshes with the internal gear 33 and the other set with'the internal gear 32. As is clear from Figure 8, this makes the pinion eccentric with respect to the gears 33 and 32 and for this reason, as is common in this structure, a filler piece 33 is provided. A bearing 33 is interposed between the shaft 34 and the member 3| and a screw and washer 33 are provided to hold the inner race of the bearing 33 on the end thereof. A pair of plates 45 are clamped to the sides of the eccentric sleeve 43 and the filler piece 33-, as 'is clear from Figure 6, to form a single unit rotatable with shaft 34.

Extending between the plates I5 is a rod 45 which is slidably mounted therein and is provided with a clamp 41 in which the compensating sheave 43 is rotatably mounted. The cable passes around this sheave through the hook pulley block 52, through the pairs of guide rollers G and through an opening in the casing C to and around the cable drum 23. The two ends of the cable are attached to the drum in any suitable manner, as by means of the pins 5| as shown in Figure 6. The groove in the cable drum is, of course, of reverse pitch so that as the drum revolves the cable winds thereonto from the outer ends towards the center and then unwinds in a reverse direction. The guide rollers G are mounted in a pair of bars 5' and 5 which are slidably mounted on the cross-bracing rods 2' and 3'. These bars are provided with pairs of rollers R which lie in the cable grooves of the cable drum so that as the drum revolves these bars move towards and away from each other, guiding the cable 53 through the de rollers G properly to and from the drum.

Pivotally mounted on the bar 3 is a lever 53 which is pivotally connected at its lower end to a rod 54 which has an enlarged end and a collar 55 mounted thereon and spaced from the enlarged end. The rod 54 passes through an extending lug 55 formed integral with the front end of the bar 5". Secured to the lever 53 so as to project therefrom at right angles is a lever 51, the function of which will be described later.

Secured to the outer face of disc 22, see Figure 6, is a ring 53 of insulating material, to the outer face of which, in turn, are secured the three slip rings 5| to which the field windings connect. In a suitable insulating housing 52 are mounted the three spring-pressed slip ring brushes 53 which engage the slip rings 5|, respectively. The housing as shown is provided with connection terminals by means of which the circuit wires may be connected to the motor.

The cup-shaped member 54 fits over the end of the shaft 34 and is connected to it by means of a key 55. The outer configuration of this member is cylindrical and forms a brake drum engaged by the brake bands 55 which are mounted in the brake shoes 51. These brake shoes are pivotally mounted on pivot pins 59 and have a bolt and spring structure 13 at their upper ends to cause them to resiliently urge the brake bands against the brake drum. The brake bands are secured to members 55, which in turn are secured to the brake shoes 51. The springs 13, of course, always act to urge the brakes into applied position. A cam 12 lies between a pair of adjustable contact members 11 mounted on ears 58 integral with the brake shoes. The cam 12 is mounted on a shaft 13, see Figure 6, which extends through the cover plate 19 and has secured to its projecting end a horizontal lever 14 and a vertical lever 15. The lower end of lever 15 is provided with a pair of contact fingers 15, see Figure 4, positioned to engage a cam arm 11 mounted on the shaft 11 of a switch 13. This switch is interconnected with the motor circuit and brushes for controlling the motor. Secured to the ends of lever 14, which extends in both directions from the shaft 13, are

cured to the member 84, as shown. The pins 83 which project into holes in the plate 82 permit slight movement of the plate in an axial direction. The plate 82 is secured to a plunger 84 axially slidable in a bore in the end of end 34' of shaft 34. Secured to the outer face of the plate 82, as by means of rivets, is a friction ring 88 of any suitable material, such as leather. A disc 88 is positioned to be engaged by the friction ring 85 and is secured to a short threaded stud 81 having left hand threads of high pitch and cooperating with threads on the supporting member 81a secured to the outer face of the cover plate 18.

The brake 82-88 is operated in accordance with this invention by the energization and deenergization of the operating motor. In order to accomplish this the shaft 34 is provided with a cam sleeve 34* rotatably mounted thereon for movement with respect thereto through a limited angle of the order, for example, in a practical construction, of about 72. The sleeve 34 has an enlarged cylindrical end 34 which encloses a collar I34 integral with the shaft 34. Secured in the shaft at the collar, as for example by a brass fitting, as is clear from Fig. 11, is a pin 34 which extends through a pair of diametrically opposite slots 34 in the enlarged collar 34% The length of these slots in a circumferential direction is such as to permit of the relative angular movement between the shaft and sleeve of 72 mentioned above. Fitting over the shaft 34 and secured to the collar 34 by means of rivets 34 is a disc 34 which has a radial lug or extensions 34 as is clear from Figs. 6 and 11. A spiral spring 34' has one end secured in any suitable manner to the extension 34 and its other end secured by rivets to a block 34 which is set and secured in a recess in the enlarged collar 34 in any suitable manner.

The opposite end of the sleeve 34 is provided with a pair of camming surfaces 34 disposed on the end edge thereof, in diametrically opposed relation as is clear from Figs. 6 and 13. The throw of these cams is small. A diametrical slot is formed in the shaft 34 adjacent the right hand end of the sleeve 34 and intersects the axial bore in which the plunger 84 is mounted. The cam follower 34 is engaged to the right hand end of sleeve 34 and to have axial movement under the action of the cams 34, the slots in the shaft 34 being of sufficient axial length to permit of this movement. The end of the plunger 84 is formed as shown in Fig. 12 so as to have a pointed end engaging in a notch in the adjacent side of the cam follower 34 This end and notch are proportioned as shown in Fig. 12 so as to permit of a slight rocking movement between the parts to accommodate the cam follower 34 through any slight differences between the cams 34 normally supposed to be exactly the same.

The spring 34 connected in the manner shown is constructed to be stron enough to hold the parts in the position shown in Fig. 6 when the motor is de-energized. At this time, as is shown,

the pin 34 is at the lower end of the slot 34. At this time the cam follower 34 is at its right hand position, being at the high points of the cams 34 From this it follows that the plunger 84 is at its right hand position, as shown, and hence plate 82 is at its extreme right hand position. Thus if the load tends to move downwardly the brake comprising the plate 82 and disc 88 is in engagement under its maximum pressure holding the load in conjunction with the drum brake.

It is to be remembered, of course, that the plate 82 will tend to move in a counterclockwise direction when viewed from the right hand end of Fig. 6, and will because of its engagement with disc 88 cause it to rotate with it in the same direction so that the threads 81 will move the disc 88 towards the plate 82 the full amount of the movement permitted as limited by the lug 88 (Fig. 10) secured to it. This lug cooperates with the ends of a notch in a fixed plate 88 attached to the cover plate 18. The shoulders of this notch limit the amount of rotation which the disc 88. may undergo in either direction. The spring 88 is provided to always hold the disc 88 in light engagement with the friction ring 85 on the plate 82 even when plate 82 is fully withdrawn in an axial direction toward the left of Figure 6. In other words, the light spring 88 always ensures suflicient engagement between the disc 88 and the plate 82 so that counterclockwise movement of I the disc 82 under load, with the motor de-energized, will cause the disc 88 to move into maximum engagement with it.

As soon as the motor is energized to raise the load, the rotor starts to move in a clockwise direction (when viewed from the brake end) and being mounted on the sleeve 34 carries that sleeve with it and the shaft 34 because of the pin 34 Should the loaded hook tend to descend it will, of course, cause counterclockwise movement of plate 82 to move the disc 88 to the left (Fig. 6 as explained above) to fully apply the brake. This brake acts in conjunction with brake 88 which, of course, is applied when the power is turned off. However, the brake 8288 is provided to ensure that the load may not descend in the event that the brake 88 does not hold. As soon as any creeping occurs because of the failure of brake 88 to hold, brake 82-88 comes into full play and by the nature of its construc tion and manner of operation holds with a certainty.

In order to lower the load the motor is energized in the reverse direction which energization is immediately followed by a movement of the armature 35 and sleeve 34 on the shaft 34 until pin 34 strikes the upper end of slot 34' (Fig. 6) when the shaft 34 then moves with the armature. This relative movement between sleeve 34" and'shaft 34 moves the cam follower 34 to a positionwhere it may drop down to the bottom of the cam surfaces 34*, that is, move to the left (Figs. 6 and 12) permitting plunger 84 to move to the left as well as plate 82 connected thereto. This plate, as explained above, slides on the pins 83. This relieves the pressure between the brake, plate 82 and disc 88 so that the motor may lower the load with no drag due to the brake 82-88 other than the negligible amount caused by the action of spring 88 which has moved the disc 88 to the left (Fig. 6) with the plate 82 so as to always maintain the light contact therebetwecn, as explained above. At the end of the lowering operation and immediately upon de-energization cf the motor, spring 34 causes a return relative movement between the sleeve 34 and shaft 34 so that they move back to the position shown in Fig. 6, moving cam follower 34 to the right a: well as plunger 84 and plate 82. Immediately any creeping occurs from this position the brake elements 82 and 85 engage under their maximum pressure to securely hold the load.

It will be noted from Figures 1 and 5, for example, that the arm 51 on the lever 53 extends under the arm H.

From the above description of the structural details the operation of the hoist will be apparent to those skilled in the art. For the sake of completeness, however, a brief further description of the manner of operation of the device will be given. Assuming the hook loaded and the desire to lift the load, the left hand handle on cord 80, see Figure 1, is pulled downward. This causes rotation of shaft 13 and cam 12 to release the brake shoes 65a from the brake drum .64. At the same time lever 15, acting oncam lever 15, operates switch 18 to complete the circuit to the motor and cause energization thereof in a direction to rotate it and the drum in a clockwise direction when viewed from the right hand end, Fig. 1. Thus the drum revolves to wind the cable upon it, the pulleys travelling thereto being guided into the proper grooves on the drum by the guiding structure in an obvious manner.

The drum is caused to revolve in the following manner. The armature rotates in a clockwise direction causing the gear on 45 meshing with gear 32 to roll around on it. Gear member 45 therefore rotates on bearings 44 having more teeth than gear 32. The result is that gear 30 revolves at a slow speed by reason of its engagement with the other set of teeth on member 45. Thus the cable drum revolves at a greatly reduced speed in a clockwise direction, gear 30 having more teeth than the gear on 45 meshing with it. A differential motion, of course, results from the magnetic forces of action and reaction between the motor field and armature. As a practical example, gear 32 has 54 teeth on a pitch diameter of six and three-quarter inches, the gear on 45 meshing with it 46 teeth on a pitch diameter of five and three-quarter inches, gear 30 has 61 teeth on a pitch diameter of six and one-tenth inches and the gear on 45 meshing with it has 51 teeth and a pitch diameter of five and one-tenth inches. This gives a speed reduction of sixty-four to one.

When the load has been lifted to the desired amount the operator releases the handle which returns to neutral position, at which time switch I8 is turned off and 'cam 12 is turned back so that the springs may apply the brake shoes 56 to the brake drum, thereby holding the load at that position. To cause the load to descend, the right hand handle on cord 80 is operated to move the lever 74 to the opposite position sothat switch I8 connects the motor in circuit in a reverse direction effecting a reverse movement of all the parts. It is not necessary to repeat here the action of the brake 82-85 in the event that the load tends to creep downwardly when the motor is de-energized or to explain how the brake 8285 is released when the load is lowered but is automatically brought back into play when the motor is de-energized.

If the apparatus is operating to lift a load and the operator forgets to turn off the switch 15, it will be turned off automatically in the following manner. When the load is at a safe upper limit of movement, the lug 55 engages the collar 55 on rod 54, moving the rod to the right, Figure 1, and causing lever 51 to move the lever 74 back to horizontal position, shutting off the motor.

The adjustment of the carriage arrangement to permit of mounting the hoist on an overhead I-beam and adjusting it for various sized beams has already been described. It will be seen that by reason of the supporting mounting employed but one-half of the load lifted, together with the entire weight of the hoist, is carried on the end members through the tubes l3 and bars 2, 3, 5 and 6, leaving only half of the weight of the load lifted to be supported by the drum and associated parts. This makes it possible to use lighter structural members in many places in the hoist and makes for longer life and greater safety.

From the above description it will be apparent "'to those skilled in the art that the principles of this invention and the physical structures employed to accomplish them may readily be varied by those who are familiar with the art without departure from the novel scope of the subject matter hereof. We do not, therefore, desire to be strictly limited to the disclosure as given for purposes of illustration, but rather to the scope of the appended claims.

What we seek to secure by Letters Patent is:

1. A hoist mechanism of the type described including a cable drum, a motor mounted within said drum including a field secured to the drum, a shaft journaled for rotation, an armature mounted on said shaft for rotation therewith and arranged to have limited relative rotational movement with respect thereto, a gear train for connecting said shaft with said drum whereby when the motor is energized the drum rotates, and a brake mechanism including a relatively fixed member and a member mounted on said shaft for rotation therewith and axial movement with respect thereto, and means operated by the relative limited rotational movement of the armature on the shaft for moving said second member axially towards or away from said relatively fixed member.

2. In a hoist mechanism the combination including a cable drum, a reversible electric motor having a rotor and shaft operatively connected to said drum to rotate it, said rotor being capable of limited rotational movement on the shaft, a brake mechanism including a member, supported for limited rotative and axial movement, and a rotatable member, connected to the motor shaft for rotation therewith, and having limited axial movement with respect to said first member, means on the motor shaft and operated by the rotor upon its movement on said shaft for causing movement of said members towards each other upon de-energization 0f the motor and initial reverse movement of the drum after energization for operation of the drum in one direction, and means acting to always hold said members in contact.

3. In a mechanism of the type described, the combination including a cable drum, a reversible electric motor having an armature and shaft, said shaft being operatively connected to said drum to rotate it in either direction, a sleeve interposed between the armature and the shaft and secured to the armature, said sleeve being capable of limited rotational movement on the shaft, a brake having a relatively fixed contact member and a contact member rotatable with said shaft, and means actuated by the sleeve upon relative movement of the sleeve on the shaft to engage the contact members of the brake mechanism upon deenergization of the motor and initial operation thereof in a reverse direction and to disengage the contact members upon energization of the motor.

4. In a hoist mechanisnnthe combination including a cable drum, a reversible electric motor having an armature and shaft operatively connected to said drum to rotate it, the armature being movable on the shaft to a limited extent, a brake mechanism including a member supported for limited rotative' and axial movement, and a rotatable member slidably connected to said shaft for rotation therewith and limited axial movement with respect to said first member, and means actuated by the armature when it moves on the shaftfor causing axial movement with respect to the armature of both said members so that they move toward each other upon deenergization of the motor and initial reverse movement of the drum, after energization for operation of the drum in one direction.

5. In a hoist mechanism, the combination including a cable drum, a reversible electric motor having a rotor and shaft operatively connected to said drum to rotate it, a brake mechanism including a member supported for limited rotative and axial movement, and a rotatable member connected to the motor shaft for rotation therewith and having limited axial movement with respect to said first member, and means actuated by the rotor for causing axial movement 01' both of said members toward each other upon deenergization of the motor and initial reverse movement of the drum, after energization for operation of the drum in one direction, and for moving both of said members away from each other in an axial direction upon energization of the motor in said reverse direction.

6. In a device of the type described, the combination including a motor having a shaft and an armature, the armature being mounted on the shaft for movement on the shaft, means for limiting the movement of the armature on the shaft, means for normally holding the armature at one of its limits of movement, and a brake mechanism operated by the armature when it moves on the shaft, said brake mechanism including a pair of contacting members, one of such members being mounted on said shaft for rotation with it, and axial movement with respect to it, and the other of said members being mounted on a support fixed with respect to said shaft so as to be capable of limited axial and rotational movement with respect to the first of said members.

7. In a device of the type described, the combination including a cable drum, a motor having an armature and a shaft mounted for relative rotation with respect to each other, means for limiting the relative rotation of the armature on the shaft, means for normally holding the armature and shaft at one of their limits of relative rotation, means for connecting the motor to the drum to rotate it, a brake mechanism comprising a pair of contacting members and a rod slidably mounted in said shaft and engaged by said armature, one of said members being mounted on saidrod and the other of said members being mounted on a support fixed with respect to' said shaft so as to have limited rotational and axial movement with respect to the shaft, relative movement of the armature with respect to the shaft causing axial movement of said rod and the member mounted on it.

PRESTON WHITCOMB. GEORGE A. MITCHELL.

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