Source: http://www.google.com/patents/US4776236?dq=6,250,774
Timestamp: 2016-07-28 20:32:12
Document Index: 376489689

Matched Legal Cases: ['arts 93', 'art 95', 'art 93', 'art 95', 'art 94', 'art 96', 'arts 93', 'arts 93']

Patent US4776236 - No-slip, imposed differential - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA no-slip, imposed differential uses a first unlimited slip differential 15 connected for driving a pair of axle shafts 16 and 17 and a second unlimited slip differential 20 connected between a pair of control shafts 22 and 23. One of the axle shafts and one of the control shafts are connected for rotation...http://www.google.com/patents/US4776236?utm_source=gb-gplus-sharePatent US4776236 - No-slip, imposed differentialAdvanced Patent SearchPublication numberUS4776236 APublication typeGrantApplication numberUS 07/027,741Publication dateOct 11, 1988Filing dateMar 19, 1987Priority dateOct 21, 1983Fee statusPaidPublication number027741, 07027741, US 4776236 A, US 4776236A, US-A-4776236, US4776236 A, US4776236AInventorsVernon E. Gleasman, Keith E. Gleasman, James Y. GleasmanOriginal AssigneeGleasman Vernon E, Gleasman Keith E, Gleasman James YExport CitationBiBTeX, EndNote, RefManPatent Citations (18), Referenced by (46), Classifications (11), Legal Events (6) External Links: USPTO, USPTO Assignment, EspacenetNo-slip, imposed differential
US 4776236 AAbstract
A no-slip, imposed differential uses a first unlimited slip differential 15 connected for driving a pair of axle shafts 16 and 17 and a second unlimited slip differential 20 connected between a pair of control shafts 22 and 23. One of the axle shafts and one of the control shafts are connected for rotation in the same direction, and the other axle shaft and the other control shaft are connected for rotation in opposite directions. An input control gear 40 meshed with a ring gear 21 for second differential 20 can rotate control shafts 22 and 23 to impose differential rotation on axle shafts 16 and 17 via the shaft connecting means. This provides a no-slip drive when control gear 40 is not turning and a steering drive by imposed differential rotation when control gear 40 turns. A clutched power take-off 82 can direct propulsion torque to the steering control input for rapid pivot turns.
1. In a no-slip steer drive system having a drive differential dividing driving torque between drive axles and having a steering differential dividing steering control torque between a pair of control shafts respectively connected additively and subtractively with said drive axles, the improvement comprising:a. a steering control motor that is rotationally independent of said driving torque for providing said steering control torque to a worm gear turned by said steering control motor and meshed with a reducing worm wheel forming a ring gear for a casing of said steering differential so that said steering control torque, continuously input to said steering differential, turns said casing to turn said control shafts but cannot be turned by said casing; b. said steering control motor being rotatable when said drive differential is not turning said drive axles so that said steering control torque can counterrotate said drive axles for pivot turning without moving forward or backward; and c. said drive axles extending from said drive differential to a region of said additive and subtractive connection of said control shafts to said drive axles so that drive torque from a tendency of one of said drive axles to slip is transmitted via said control shafts and said steering control differential to an opposite one of said drive axles not tending to slip. 2. The improvement of claim 1 including a clutched system for accomplishing said pivot turning by diverting said driving torque from said drive differential to said worm wheel to apply said driving torque to said worm wheel without turning said drive differential.
3. The improvement of claim 2 wherein said clutched system includes a power take-off for transmitting said driving torque to said worm wheel.
4. A method of no-slip steer driving a vehicle having a main propulsion engine providing driving torque differentiated between drive axles and having a steering control differential differentiating steering control torque between control shafts connected additively and subtractively with said drive axles, said method comprising:a. using a steering control motor that is rotationally independent of said main propulsion engine for providing said steering control torque, and applying said steering control torque to turn a worm gear meshed with a reducing worm wheel turning a casing of said steering control differential so that said casing cannot rotate said worm gear and said casing rotates only when said steering control torque rotates said worm gear; b. stopping said steering control motor and using said steering control motor as a torque-resisting load holding said worm gear against rotation during straight-ahead movement, and driving said steering control motor when said main propulsion engine is not providing driving torque to said drive axles for pivot turning by counterrotating said drive axles without moving forward or backward; and c. transmitting drive torque from one of said drive axles tending to slip via said control shafts and said steering control differential to an opposite one of said drive axles not tending to slip. 5. The method of claim 4 including applying said driving torque to said worm wheel for said pivot turning.
6. The method of claim 5 including using a clutched power take-off for transmitting said driving torque from said main propulsion engine to said worm wheel.
7. A no-slip steer drive system having a main propulsion engine providing driving torque via a drive differential to a pair of opposed axle shafts and having a separate steering control differential differentiating steering control torque to a pair of control shafts respectively connected additively and subtractively with said axle shafts, said system comprising:a. a steering control motor that is rotationally independent of said main propulsion engine, said steering control motor providing said steering control torque to a casing of said steering control differential so that said control shafts are turned in response to rotation of said casing; b. a worm gear turned by said steering control motor; c. a reducing worm wheel meshed with said worm gear and turning with said casing of said steering control differential so that said casing turns said control shafts and cannot turn said worm gear; d. said axle shafts extending from said drive differential to a region of said additive and subtractive connection of said control shafts with said axle shafts so that drive torque from a tendency of one of said drive axles to slip is transmitted via said control shafts and said steering control differential to an opposite one of said drive axles not tending to slip; and e. said steering control motor being arranged for holding said worm gear against rotation during straight-ahead movement and for rotating said worm gear, without any of said driving torque being applied to said drive differential, for counterrotating said axle shafts for pivot turning without forward or backward movement. 8. The system of claim 7 including a power take-off directing said driving torque from said main propulsion engine to said worm wheel for propulsion drive assistance for said pivot turning.
9. The system of claim 8 including a clutch for selectively engaging said driving torque with said worm wheel.
10. The system of claim 7 wherein said worm wheel is a ring gear for said casing of said steering control differential.
11. A no-slip steer drive system for a vehicle having a main propulsion engine providing driving torque to a drive differential connected between drive axles on opposite sides of said vehicle and having a steering control differential connected between a pair of control shafts respectively connected additively and subtractively with said axle shafts, said system comprising:a. a steering control motor that is rotationally independent of said main propulsion engine for inputting said steering control torque to a casing of said steering control differential for turning said control shafts; b. said steering control differential having a ring gear formed as a worm wheel; c. a worm gear driven by said steering control motor being meshed with said worm wheel; d. said worm gear and said worm wheel forming a reduction drive so that said worm gear can turn said casing of said steering control differential, but said casing cannot turn said worm gear; e. said steering control motor being arranged for holding said worm gear against rotation during straight-ahead movement of said vehicle and for rotating said worm gear or counter-rotating said drive axles to pivot turn said vehicle when said main propulsion engine is not providing driving torque to said drive differential for moving said vehicle forward or backward; and f. said drive axles extending from said drive differential to a region of said additive and subtractive connection with said control shafts so that drive torque from a tendency of one of said drive axles to slip is transmitted through said control shafts and said steering control differential to an opposite one of said drive axles not tending to slip. 12. The system of claim 11 including a clutch system for directing said driving torque to said worm wheel for using said driving torque for powering pivot turns.
13. The system of claim 12 wherein said clutch system disengages said driving torque from said drive differential during said pivot turns.
14. The system of claim 13 wherein said clutch system engages and disengages a power take-off from said driving torque.
This application is a continuation-in-part of pending parent application Ser. No. 818,951, filed Jan. 15, 1986, entitled NO-SLIP, IMPOSED DIFFERENTIAL, which parent application is a Continuation of grandparent application Ser. No. 544,390, filed Oct. 21, 1983, entitled NO-SLIP, IMPOSED DIFFERENTIAL, both parent and grandparent applications being abandoned upon the filing of successor applications.
In searching for a better solution for these and other problems, we have discovered a way of imposing differential rotation on axle shafts for steering both track-laying and wheeled vehicles. Our imposed differential can simultaneously drive wheels or tracks forward on one side of a vehicle and backward on the other side to allow pivot turns around a central point without overly stressing tracks or wheels. Our system can apply main propulsion drive torque to such pivot turns to accomplish them rapidly, if necessary. Our discovery also provides a no-slip differential that drives both sides of a vehicle regardless of relative traction and applies more power to the side with the greater traction.
Our invention also leads to an improvement in wheel dynamometers for testing drive axles. It allows differential rotation to be imposed realistically on axle shafts under load. Our invention also accomplishes these advances by combining inexpensive and well-known components in ways that produce improved results.
Our no-slip, imposed differential applies to a drive system having a main propulsion engine providing drive torque via a drive differential to a pair of opposed axle shafts and having a separate steering control differential differentiating steering control torque to a pair of control shafts respectively connected additively and subtractively with the axle shafts. Our system uses a steering control motor that is rotationally independent of the main propulsion engine and the driving torque, and the steering control motor provides steering control torque to a casing of the steering control differential so that the control shafts turn in response to rotation of the casing. A worm gear is turned by the steering control motor and is meshed with a reducing worm wheel, preferably forming a ring gear for the casing of the steering control differential. This allows the worm gear to turn the casing and the control shafts for steering the vehicle, but does not allow the control shafts or the casing to turn the worm gear. For pivot turns power assisted by main propulsion torque, a power take-off from the drive torque is clutched into the steering control drive train to turn the worm wheel for rotating the casing and the control shafts.
FIG. 3 is a schematic view of a vehicle pivot turn made possible by our imposed differential; and
FIG. 4 is a schematic view of a clutch system for a power take-off applying drive torque to the steering control input for powering pivot turns.
Gear 40 can be turned by several mechanisms, depending on the objective. For steering purposes, gear 40 can be turned by a steering shaft joined to control gear 40 and manually turned by a driver. Steering mechanisms can also use motors for turning gear 40. Alternatives include a DC starter motor 41 electrically turned via a rheostat in a steering system and a hydraulic or pneumatic motor turned by a vehicle's hydraulic or pneumatic system in response to a steering control.
Several drive interconnections are possible between the control shafts and the axle shafts of the test axle mounted on wheel dynamometer 50. One preferred arrangement shown in FIG. 2 uses meshed gears 26 and 32 fixed respectively to test axle shaft 16 and control shaft 22 for opposite direction rotation. Sprockets 57 and 53, coupled by a chain 54 and fixed respectively to test axle shaft 57 and control shaft 23, provide same direction rotation. Belts and other gearing arrangements are also possible.
To elaborate on this, consider a vehicle rolling straight ahead with its axle shafts 16 and 17 turning uniformly in the same direction. Control gear 40 is stationary for straight ahead motion; and since control gear 40 is preferably a worm gear, a worm wheel 21 of control differential 20 cannot turn. Control shafts 22 and 23, by their driving connections with the axle shafts, rotate differentially in opposite directions, which control differential 20 accommodates.
Such differential rotation is added to whatever forward or rearward rotation of the axle shafts is occurring at the time. So if a vehicle is moving forward or backwrd when control gear 40 turns, the differential rotation advances and retards opposite axle shafts and makes the vehicle turn.
Pivot turns can also be power assisted or powered totally by driving torque to be executed more rapidly. Since a vehicle is not using driving torque for forward or rearward movement when pivot turning occurs, driving torque is available for powering pivot turns; and FIG. 4 schematically shows a preferred way of accomplishing this.
A power take-off 92 from a transmission 91 or main propulsion engine 90 rotates clutch parts 93 and 94. Either of these can be engaged with its counterpart 95 and 96, each of which are meshed with bevel gear 97 rotating with worm gear 40. To apply driving torque to a pivot turn in one direction, clutch part 93 is meshed with clutch part 95 to turn bevel gear 97 in the desired direction for rotating worm gear 40 and worm wheel 21. Steering control motor 41 can be unclutched for engine powered pivot turns or can combine its torque with the torque provided via bevel gear 97. For applying propulsion torque to power a pivot turn in an opposite direction, clutch part 94 meshes with its counterpart 96, driving bevel gear 97 in an opposite direction and turning worm 40 and worm wheel 21 in an opposite direction.
A power take-off can be derived from many points along the main propulsion drive train, including engine 90, transmission 91, and other points. A power take-off can be made to turn continuously or be operated only when needed for pivot turns. The engagement of clutch parts 93 and 94 can be made responsive to full turn of a steering wheel, calling for a pivot turn; and any engagement of clutch parts 93 and 94 can be locked out during forward or rearward movement of the vehicle, if desired. Propulsion assisted pivot turning can also be applied to worm wheel 21 by a worm gear separate from steering control input worm gear 40, and different clutch arrangements can be used for engaging and disengaging the diversion of drive torque for pivot turning. Applying drive torque to the steering control input allows pivot turns to be accomplished more rapidly than would be possible with a small sized steering control motor 41, adequate for forward and rearward steering.
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