US2880814A - Garden tractor - Google Patents

Description

M. L. SENSENIG ETAL 2,880,814

April 7, 1959 A GARDEN TRACTOR 3 Sheets-Sheet 1 Filed April 24, 1956 lIVl/ENTURS v M. L. SENSENIG ET AL 2,880,814

April 7, 1959 GARDEN TRACTOR Filed April 24, 1956 dmlw - A TTOR/VLY M. SENSENIG ETAL 7 2,880,814

' GARDEN'TRACTOR April 7, 1959 Filed April 24, 1956 Sheets-Sheet s United States Patent GARDEN TRACTOR Miles L. Sensenig, Lancaster, and William H. Robinson,

Honeybrook, Pa., assignors to Sperry Rand Corporation, New Holland, Pa., a corporation of Delaware The present invention relates generally to self-propelled, wheeled vehicles. More particularly, the invention relates to an improvement in the invention shown and described in our US. Patent No. 2,778,437 issued January 22, 1957.

In our patent a vehicle is shown of the class which has independently rotatable, laterally spaced, drive wheels adapted to be driven forwardly from a power unit on the vehicle through separate power means, each of which includes a belt drive having a belt tightener associated therewith. The belt tighteners for the respective belt drives are controlled through actuation of the vehicle steering mechanism to permit slippage of the belt drive to one of the wheels during the making of a turn to thereby provide a differential action between the drive wheels.

While the drive mechanism disclosed in our patent constitutes a substantial improvement over the prior art, it is deficient in that it is able to drive the vehicle on which it is mounted in a forward direction 'only,

there being no provision for operation in reverse.

The primary object of this invention is to improve the drive mechanism described in our patent, whereby it may be operated selectively to drive the vehicle on which it is used either forward or in reverse.

Another object of this invention is to incorporate reverse drive means in the drive mechanism disclosed in our patent in such a manner that the structure of the drive mechanism is not materially altered to accommodate the reverse drive means.

A further object of this invention is to provide drive control means whereby the vehicle drive may bet set, selectively, to run either forward, in reverse, or to idle in neutral.

A still further object of this invention is to provide reverse drive means, and control means, of the character described of relatively simple construction and few parts.

Other objects of this invention will be apparent hereinafter from the specification and from the recital in of Fig. 4 looking in the direction of the arrows and showing the portion of the drive mechanism illustrated in reverse position;

Fig. 4 is a fragmentary section taken on the line '4-4 of Fig. 3 and looking in the direction of the arrows;

and

Fig. 5 is a fragmentary view illustrating the mounting for the tractor shift handle.

Referring now to the drawings by numerals of reference, designates generally the rigid frame or chassis of the vehicle which includes laterally spaced longitudinal side members 10a and 10b interconnected by a front member 100. The frame also comprises vertical bracket members 10e (Fig. 1) depending from the rear ends of side members 10a and 10b. Angularly projecting brace members 11 (Fig. 1) and 11 (Fig. 3) extend from the lower ends of members 10e upwardly to the side members. Brace members 11 and 11' are connected by a cross member 10d which constitutes the rear frame member of the chassis and by a medial cross member 10 All of these brackets and frame members are rigidly connected by welding or other suitable means.

A fixed or dead rear axle 12 for the vehicle extends laterally between the lower ends of bracket members 102 and brace members 11 and 11. Freely rotatable on opposite ends of axle 12, for relatively independent rotation, are laterally spaced drive wheels 13 and 13', respectively, which are driven forwardly or in reverse by power transmitting means hereinafter described. The power transmitting means includes forward power transmission mechanisms for the respective rear drive wheels which are generally identical, therefore, only the forward drive mechanism to the wheel 13 will be described, it being understood that the mechanism for wheel 13' will be designated by similar but primed reference characters.

Wheel 13 has a sprocket 14 fixed concentrically to its hub. This sprocket is driven through a usual sprocket chain 15 from a drive sprocket 16 (Figs. 1, 2 and 4) fixed on a counter shaft 17. Shaft 17 is journaled transversely of frame 10 in spaced bearing blocks 23 and 23a (Fig. 4) bolted to brace member 11 and a longitudinal support member 11a, respectively. Member 11a is welded to rear end cross member 10d. Shaft 17 has a pulley or sheave 18 keyed thereon and driven by a belt 19 from a drive pulley or sheave 20 (Figs. 1 and 2) fixed on the output shaft 21 of a power unit 22.

Unit 22 is preferably in the form of a small internal combustion engine carried on frame 10. It is supported on transverse members 25 and 26 extending from frame member 10a to frame member 10b and secured to each of said members by bolts 27 and 28, respectively.

In order to provide a ready means for simultaneously adjusting the tension of the drive belts 19 and 19', the motor 22, its output shaft 21 and drive pulleys 20-20 are made longitudinally adjustable on the frame 10. In the present instance this is easily and simply accomplished by providing the members 25 and 26 with longitudinally extending slots 27' and 28, respectively, to receive their cooperating bolts 27-48, whereby the motor 22 may be adjusted longitudinally on the frame 10 within the limits permitted by these slots.

The steering mechanism for the vehicle is exemplified by a front dirigible or steering wheel, not shown, rotatably supported between the depending legs of a usual bicycle type fork 31 (Fig. 1) mounted at the lower end of a vertical steering shaft or spindle 32 which is rotatably journaled at its lower end through the front cross frame member 10c. Steering movement is imparted to the wheel on rotation of shaft 32 through means fully shown and described in our co-pending application previously referred to.

Mechanism is provided for individually controlling the forward power transmission mechanisms to the relatively laterally opposed rear drive wheels 1313' to permit slippage between the inside wheel, and the power transmission connected thereto, during the making of a turn. This is accomplished responsive to actuation of the steering mechanism and serves as a simplified positively acting and economical substitute for the usual differential gearing conventionally employed in automotive structures.

1 ever, that the belt tighteners 40 and 40 operate normally during straight ahead movement of the tractor or vehicle tomaintain both of these belt drives operative and thus maintain drives to both of the rear wheels 13 and 13.

.Belt tighteners 40 and 40' are of similar construction in all material respects and it will, therefore, sufiice to vdescribe only the belt tightener 40, it being understood that -.the corresponding parts of belt tightener 46 will .be designated by similar, but primed reference characters. this in mind, it will be seen that belt tightener 40 consists essentially of a lever having arms 41 and '42 (Figs. 1 and 2)., respectively, rigidly supported by a .sleeve or hub 43 by means of which the lever is medially fulcrumed on cross shaft 44 fixedly supported by and beneath the cross member 25 by usual hangers 45. Rigidly supported on and constituting a part of the lever arm 41 are laterally opposed brackets 46 between which -is,.-freel-y rotatably journaled a tightener or idler wheel 47'moveable into and out of tightening engagement with the associated drive belt 19 responsive to rocking of the lever about its fulcrum 44.

Such rocking of the belt tightener or lever 49 is automatically controlled responsive to actuation of the vehicle steering mechanism by means 'of a control cam 48 connected to the steering mechanism for movement responsive to operative movement of the steering mechanism.

The forwardly projecting arms 42 and 42 of both tighteners 40 and 40 are disposed for cooperation with the control cam 48. Control cam 48 is fixedly supported on steering fork 31 concentric to its steering shaft 32 for rotary movement with the steering shaft 32, fork 31, and the dirigible'wheel carried thereon.

The lever arms 42 and 42 project from their fulcrurn sleeves 43-43 in radial directions to the rotational axis of the cam 48. The cam 48, in turn, has-an axially upwardly directed cam face, including relatively circumferentially spaced inclined cam surfaces 48a and 48b which, in the straight ahead position of the steering mechanism and the dirigible wheel are disposed on opposite sides of the ends ofthe respective arms 42-42. In orderto facilitate the cooperation between the arms 42 and .42 and cam 48 they are preferably provided with follower rollers 49-49. These rollers 49 and 49 preferably'are rotatably supported on pintles 50-50 threade dtintoand constituting extensions of the lever arms 42 and 42'.

The. belt tighteners or levers 40-40 are normally urged resiliently toward operative tightening engagement with their respective drive belts by means of springs, .suclras 52 (Fig. 1) connected under tension between the trear-wardly extending lever arms 41 and 41' and chassis 10.

Intorder to permit belt tightening positioning of the :belt tighteners 40-40 in the straight ahead position of "the steering mechanism, the cam 48 is provided with a *recessed or depressed portion 480 between the inclined cam "surfaces 48a and 48b so that the follower rollers 49 and 49 may normally be received in this recessed-por- *tion. From the depressed or recessed portion-48c both cam surfaces '48:: and 48b are inclined upwardly'totheir junctures with the respective radially co-planar surfaces #821 and 48e, respectively, shown in Fig. 2.

Thepurpose of thesurfaces 48d and 48e is simply to insure that the lever 40 or 40' is maintained out of lightening engagement with its associated belt 19 .or 19", as thecase may be, after the steering mechanism has once been turned to cause the co-action between the follower 49 or 49 and cam surface 48a or 48b to disengage the belt drive associated with either of said levers.

It is desirable to provide some means for disconnecting the forward drive to both rear wheels 13 and 13 from the power source 22 in the manner of a usual automotive clutch, so that the vehicle may be brought to rest with the motor 22 running. For this purpose we adapt the belt tighteners 4t) and 40 to permit simultaneous slippage of the belts 19-19 independently of the position of the control cam or element 48. Such adaptation is made by means of a cam or control shaft 53 suitably journaled cross-wise of the frame 10 and having cam lobes 54 and 54', respectively, fixed thereon .in positions for simultaneous engagement with the rearwardly extending arms 41 and 41' of the levers 40-40, respectively. The cam shaft 53 may alternatively be referred to as a rock shaft, since it is actuated by rocking it into operative engagement with the lever arms 41-41. Such rocking movement of the shaft 53 is manually produced through a shift handle 55 which is mounted and operable, in a manner hereafter described, against fingers 58-58 on a sleeve 59 fixed on shaft 53.

The structure just described i generally the same as that shown in our patent previously mentioned. Appli- 'cants improvement resides in the means incorporated into the drive system to enable an operator of the tractor to drive it in reverse. This structure will now be-described.

Mounted on output shaft 21 of power unit 22 and interposed between drive pulleys 20-20 is a reverse -drive pulley 6t). Trained over pulley 60 and a driven pulley 61, spaced rearwardly therefrom, is a normally slack endless belt 62. Driven pulley 61 is keyed on a shaft 65 (Figs. 3 and 4) supported in the spaced parallel arms 66 of an upwardly extending rocker member :or yoke 67. Through the upper ends of arms 66 extends -,a shaft 68 (Fig. 3) about which rocker 67 is adapted to pivot to thereby move toward or away from drive sheaves 18-18, to wheels 13-13, respectively. Pivot shaft 68 is supported at one end in a block 69 (Figs. 1 and 2) mounted on chassis frame member 10a and at its opposite end in a pedestal 70 projecting upwardly from frame member 11a.

Fixed to shaft 65 on opposite sides of driven pulley'6l are the hubs of friction wheels 71-71 of rubber or some other similar friction material. Wheels 71-71 extend between the upper and lower reaches of endless belts 19-19, respectively, and in the same planes as sheaves 18-18, respectively.

Rocker member 67 is biased in a clockwise direction (Fig. 3) about pivot shaft 68 by a spring 72, one end of which is connected to the rocker member and the other end of which is connected to a pin 72a fastened .to cross member 10f. Movement of rocker.67,= and :the

wheels 71-71 thereon, toward or away from pulleys 18-18 is controlled by an arm 73 connected 'at74 to the lower end of the rocker. The opposite end of1arm 73 is threaded; and, this threaded endis received ina clevis 75 pivotally connected at 76 (Fig. l) to an overcenter link 77. Link 77 is rigidly connected to-and extends radially from a sleeve 79 (Fig. 5) freely mounted on cam shaft 53 inwardly of sleeve 59 fixed on shaft .frame members 87 and 88 of the tractor super structure.

Shift plate 86 has a U-shaped slot comprising parallel slot-arms 90-91 and a forward cross slot 92 (Fig. 2). Ann 90, arm 91, and cross slot 92 comprise the forward, reverse, and neutral positions, respectively, for handle 55.

The operation of the drive mechanism will now be described. Placing handle 55 vertically and in the neutral slot 92 in shift plate 86, the operator starts power unit 22. Output shaft 21 drives the three pulleys mounted thereon, namely, forward drive pulleys 20-20 and reverse drive pulley 60. However, no drive is imparted to the vehicle because forward drive belts 19-19 and reverse drive belt 62 are slack, with belt tighteners 47-47 dropped as shown in Fig. 2 and away from belt tightening position and rocker arm 67 pivoted away 'from sheaves 18-18.

To drive the tractor forwardly the operator moves shift handle 55 laterally inwardly in cross-slot 92, or toward the tractor body. This cocks the lower end of the shift handle outwardly, the handle pivoting about pin 82. The

'lower end of the shift handle then extends between forward control fingers 58-58. The operator then pulls handle 55 rearwardly, or clockwise from the position shown in solid lines in Fig. l to the position shown in dotted lines. With this action cam shaft 53 is rotated and the cam lobes 54-54 engaging belt tighteners 40-40, respectively, are retracted. Springs 52, constantly biasing the belt tighteners toward tightening position are now operative to lift wheels 47-47 into engagement with belt 19-19, respectively, to tighten them. Thereupon, a forward drive is transmitted through belts 19-19, sheaves 18-18, shafts 17-17, sprockets 16-16, chains 15- power source 22 and both of the rear drive wheels 13 and I 13. When the operator actuates the steering mechanism to cause the vehicle to turn to the left, it will be seen that rotation of the cam 48 with the steering mechanism, including the ground or dirigible wheel, its supporting fork 31, and shaft 32, will sequentially rotate first the inclined cam surface 48a and then the surface 48d beneath the roller 49, thereby rocking the lever 40 about its fulcrum 43 as the roller 49 rides up inclined cam surface 48a and withdrawing the wheel or sheave 47 from tightening engagement with the belt 19. As the roller 49 rides onto the cam surface 48d, this surface will cooperate with roller 49 to maintain the disengaged position of the tightener 40. Throughout such coaction between roller 49 and the cam surfaces 48a and 48d it will be seen that the roller 49 will remain between the two inclined cam surfaces 48a and 48b thus to maintain the drive to its associated rear wheel 13. Thus there will be permitted slippage in the drive to the wheel 13 on the inner side of the turn, while the wheel 13 on the outer side of the turn will have a continuous drive imparted thereto. Accordingly, there will be permitted a differential action as between the two drive wheels 13 and 13, and the driving mechanism may thus be made to accomplish the same function as a usual differential gearing.

When the vehicle is returned to straight ahead travel, the drive to wheel 13 will be reinstated. If, thereafter, the tractor operator steers the tractor to the right, the drive to wheel 13 will be maintained, but the drive to wheel 13 will be broken as roller 49 rides up on surfaces 48b and 48e of control cam 48.

To stop the forward drive of the tractor, the operator 6 moves shift handle 55 forwardly or counter-clockwise. The lower end of the handle engaging finger 58 causes cam shaft 53 to pivot. Cam lobes 54-54 engage tighteners 40-40 forcing them to pivot about their fulcrum 44; and, tightener wheels 47-47 are simultaneously moved downwardly and away from belts 19-19 to loosen the belts. The forward drive to both wheels 13-13 thus ceases.

If the operator wishes to back-up the tractor, he moves shift handle 55 in cross slot 92 laterally outwardly relative to the tractor body. This cocks the lower end of the handle inwardly and between reverse control fingers -80 on sleeve 79 on cam shaft 53, as shown in Fig. 5. Movement of handle 55 rearwardly or clockwise (Fig. 1) and into slot arm 91 results in rotating sleeve 79 counterclockwise. Over-center link 77 is swung from the position shown in solid lines in Fig. 1 to the position shown in dotted lines and control rod 73 is pushed rearwardly. The rearward movement of rod 73 pivots rocker 67 about its pivot 68 bringing friction wheels 71-71 into tight engagement with sheaves 18-18 (Figs. 3 and 4). At the same time, endless belt 62 is tightened whereby a driving force is transmitted from pulley 60 to pulley 61. Pulley 61 rotates shaft 65 and friction wheels 71-71 thereon clockwise (Fig. 1). The friction wheels impart a counterclockwise rotation to sheaves 18-18, which through 17-17, 16-16, 15-15, and 14-14 is transmitted to wheels 13-13 to drive the tractor in reverse.

When the tractor has been backed a desired distance, shift handle 55 is moved back to neutral, that is, to cross slot 92. The lower end of the handle engaging finger 80 on sleeve 79 rotates the sleeve clockwise and swings overcenter link 77 back to starting position (Fig. 1). Control rod 73 is shifted forwardly swinging rocker 67 about its pivot 68 and moving wheels 71-71 out of engagement with sheaves 18-18' and slackening belt 62. Belts 19-19 and 62 are slack and no drive is transmitted to the drive wheels.

To insure against a drag on endless drive belts 19- 19 when the shift handle is in neutral or in reverse, a cross pin 93 (Figs. 1 and 3) is provided adjacent sheaves 18-18. Pin 93 extends transversely to the direction of movements of belts 19-19 and beneath the lower reaches of the belts. The pin engages the belts and supports them when they are slack. Thus any tendency of the belts to move when slack is overcome.

In like manner to insure against drag of belt 62 when the shift handle is in neutral or forward position a belt support member 94 is provided, as shown in Fig. 1. Member 94 is bolted to the power unit support member 25. It extends rearwardly and upwardly therefrom engaging belt 62 beneath pulley 60. It supports the weight of belt 62 when it is slack in the same manner as pin 93 supports belts 19-19.

In order to guide belt 62 between belts 19-19 and to provide means for regulating its tightness, a combined guide-tightener member 96 (Fig. 1) is provided. Member 96 comprises a resilient strip of material connected to cross-member 25 and extending rearwardly to cross-member 26 whereupon it angles upwardly to engage belt 62. The upwardly extending portion is provided with upturned sides 97 between which belt 62 is adapted to travel.

Member 96 is mounted for vertical adjustment of its belt engaging end. This is accomplished by means of an adjustment screw 98 threaded through cross-member 26 and engaging the bottom of member 96.

From the foregoing it is seen that applicants vehicle may be driven forwardly, or in reverse, or allowed to stand idle while its power unit is running, the control of the vehicle drive being simply regulated by shift handle 55. When handle 55 is in neutral, all belts are slack. When the vehicle is driven generally straight ahead belts 19-19 are tight and belt 62 is slack. Upon turning of the vehicle to the left or to the right, belt 19 or 19 is slackened, as the case may be. When the tractor is driven tightened.

Applicants drive mechanism just described contains less parts than similar mechanisms of prior design and, therefore, can be manufactured at lower cost.

While the invention has been described in connection with a particular embodiment thereof, it will be understood that it is capable of further modification and 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 fall within the scope of the invention or the limits of the appended claims.

Having thus described our invention what we claim is:

1. A self-propelled vehicle comprising a pair of laterally spaced drive wheels, a pair of spaced driven pulleys, means connecting said driven pulleys to said drive wheels whereby on rotation of the pulleys the wheels are rotated, a drive shaft, a power unit for rotating said drive shaft in one direction only, a pair of drive pulleys spacedly mounted on said drive shaft and continuously rotated thereby, a pair of normally slack endless belts trained over said drive and driven pulleys, means for tightening said endless belts so that power may be transmitted to said driven pulleys, a pair of friction wheels, each of said friction wheels being disposed between the upper andlower reaches of one of said endless belts co-planar with one of said driven pulleys and normally spaced therefrom, means for rotating said friction wheels comprising a' single drive pulley mounted on said drive shaft and constantly rotated thereby, a single driven pulley connected to said friction wheels, a normally slack single endless belt trained over said single drive and driven pulleys, means for supporting said single drive pulley and said friction wheels, and means for rocking said supporting means to move said friction wheels into engagement with said driven pulleys and to simultaneously tighten said single endless belt, and control means operable, selectively, to rock said supporting means or to actuate said belt tightening means.

v 2. In a self-propelled vehicle, a pair of separate independently rotatable drive wheels, a pair of driven pulleys connected, respectively, to said drive wheels whereby on rotation of such pulleys said wheels are rotated, a power unit including a drive shaft rotatable in one direction,

a pair of drive pulleys affixed to said shaft androtatable therewith, a pair of normally slack endless belts connecting said drive and driven pulleys, a third drive pulley afiixed to said shaft, a pair of friction wheels disposed between the reaches of said endless belts and normally spaced from and co-planar with said driven pulleys, a reverse drive pulley connected to said friction wheels to rotate them, a normally slack third endless belt connect ing said third drive pulley and said reverse drive pulley, and a unitary control means operative, selectively, to tighten said pair of belts while maintaining said third belt slack and said friction wheel spaced from said driven pulleys or to tighten said third belt and move said friction wheel into engagement with said driven pulley while maintaining said pair of belts slack.

3. In a self-propelled vehicle as recited in claim 2,-unitary control means which comprises a pivotally mounted control shaft, means for tightening said pair of belts, means connecting said control shaft to said tightening means whereby when said shaft is pivoted in one direction said pair of belts are tightened, a rocker-arm supporting said reverse drive pulley and said friction wheels, means connecting said control shaft to said rocker-arm whereby when the control shaft is pivoted in a direction opposite to said one direction said friction wheels are brought into engagement with said driven pulley and said reverse drive pulley is moved relative to said third drive pulley to tighten said third belt, and means for pivoting said control shaft in either direction.

4. In a self-propelled vehicle as recited in claim 3 wherein the vehicle has a steering mechanism, means connecting said steering mechanism to said belt tightening. means, and means operative when said control shaft is pivoted in said one direction for slackening-one of said pair of belts during the making of a tur References Cited in the file of this patent UNITED STATES PATENTS Berry Nov. 23', 1920

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