Variable speed drive mechanism

Claim 2

In a driving mechanism for a tractor or the like having a frame, a motor-driven pulley and a wheel-driving pulley, a variable-pitch sheave assembly, V-belt means operatively connecting said pulleys to said sheave assembly, an arm member pivotally carried by said frame, to swing about a pivot point on said frame, and carrying said sheave assembly, swinging movement of said arm member shifting the axis of said sheave assembly to modify the drive ratio of said pulleys, the combination of resilient biasing means operatively interconneCting said arm member and said frame for resiliently varying the distance between the axis of said sheave assembly carried by the arm member and said pivot point in a first direction to maintain driving tension on said V-belt means for transmission of power between said pulleys, operating mechanism carried by the frame for swinging said arm member and sheave assembly carried thereby about said pivot point to modify said drive ratio of said pulleys, said operating mechanism including supplemental means for varying the distance between said sheave assembly and said pivot point in opposition to said biasing means in a second direction to loosen the driving tension on said V-belt means for discontinuing the transmission of power between said pulleys, said biasing means and supplemental means being disposed relative to the said sheave assembly and pivot point for the moving of said sheave assembly in said second direction only upon the sheave assembly having been swung by said arm member to a position for low driving ratio between said pulleys.

Claim 3

The combination as claimed in claim 1 and in which said biasing means is a spring operatively interconnecting said frame and arm member yieldably to urge the arm member in said first direction, and in which said arm member is formed to permit limited movement in said first and second directions relative to said pivot point on said frame.

Claim 4

The combination as claimed in claim 1 and in which said supplemental means interconnected with said arm member and dimensioned to move the arm member in said second direction only after the arm member has carried the said sheave assembly away from the position for high driving ratio to beyond the position for low driving ratio to move said sheave assembly in said second direction only after said operating mechanism has moved said arm member carrying the sheave assembly to provide a drive ratio between said pulleys which drives the wheel-driving pulley at its low speed range.

Claim 5

The combination as claimed in claim 1 and in which said sheave assembly as it is moved in said first and second directions swings in an arc about the axis of said wheel-driving pulley to loosen and tighten the driving tension on said V-belt means.

Claim 6

In a driving mechanism for a tractor or the like having a frame, a motor-driven pulley journaled on the frame and a wheel-driving pulley journaled on the frame, a variable-pitch sheave assembly, V-belt means operatively connecting said pulleys to said sheave assembly, the axes of said pulleys being parallel and spaced-apart, and the axis of said sheave assembly being parallel to, and variably spaceable from, the respective axes of said pulleys, the combination of an arm member pivotably carried by the said frame to swing about a pivot point on said frame and carrying said sheave assembly to swing in an arc about said pivot point to variably space the axis of the sheave assembly from the respective axes of said pulleys in a range of positions between a low-speed position and a high-speed position and thereby to modify the drive ratio of said pulleys, lost-motion means operatively interconnecting said arm member and frame at said pivot point to permit the said sheave assembly to be moved between a driving position maintaining driving tension on said V-belt means and a nondriving position loosening driving tension on said V-belt means, biasing means urging the arm member carrying said sheave assembly toward driving position relative to said pivot point, and operating means operatively connected to said arm member for swinging said arm member about said pivot point to swing the sheave assembly carried thereby in said arc and thereby to modify the drive ratio of said pulleys, said operating means being arranged to move said arm member against said biasing means and to move the sheave assembly beyond the low-speed position of said range of positions and away from driving position relative to said pivot point and thereby loosen driving tension on said V-bElt means.

Claim 7

In a driving mechanism for a tractor or the like having a frame, a motor-driven pulley journaled on the frame and a wheel-driving pulley journaled on the frame, a variable-pitch sheave assembly, V-belt means operatively connecting said pulleys to said sheave assembly, the axes of said pulleys being parallel and spaced-apart, and the axis of said sheave assembly being parallel to, and variably spaceable from, the respective axes of said pulleys, the combination of an arm member pivotably carried by the said frame to swing about a pivot point on said frame and carrying said sheave assembly to swing in an arc about said pivot point to variably space the axis of the sheave assembly from the respective axes of said pulleys in a range of positions between a low-speed position and a high-speed position and thereby to modify the drive ratio of said pulleys, lost-motion means operatively interconnecting said arm member and frame at said pivot point to permit the said sheave assembly to be moved between a driving position maintaining driving tension on said V-belt means and a nondriving position loosening driving tension on said V-belt means, biasing means urging the arm member carrying said sheave assembly toward driving position relative to said pivot point, and operating means operatively connected to said arm member for swinging said arm member about said pivot point to swing the sheave assembly carried thereby in said arc and thereby to modify the drive ratio of said pulleys, said operating means being arranged to move said arm member against said biasing means and to move the sheave assembly beyond the low-speed position of said range of positions and away from driving position relative to said pivot point and thereby loosen driving tension on said V-bElt means.

Claim 8

The combination as claimed in claim 5 and which said lost-motion means is a pin in a slot, one of the pin and slot being carried by the frame and the other of the pin and slot being carried by the arm member, said pin providing said pivot point about which the arm member swings.

Claim 9

The combination as claimed in claim 6 and in which said biasing means is a spring interconnecting said pin and arm member and resiliently biasing the arm member in a direction to urge the sheave assembly toward belt-tensioning position.

Claim 10

The combination as claimed in claim 5 and including braking means for said tractor operatively interconnected with said operating means and arranged to actuate the braking means to braking position upon movement of said sheave assembly beyond said low-speed position away from said driving position and the loosening of the driving tension on said V-belt means.

Claim 11

The combination as claimed in claim 8 and including spring-biased overthrow toggle joint means operatively connected with said operating means for releasably urging said operating means to hold the sheave assembly in nondriving position and the braking means in braking position.

Claim 12

The combination as claimed in claim 5 and in which said operating means includes a pair of first pedals operable by the tractor operator and movable in opposite directions, the pressing of one pedal moving the operating means to cause the sheave assembly to move toward high-speed position, and pressing of the other pedal moving the operating means to cause the sheave assembly to move toward low-speed position and upon further pressing to cause the sheave assembly to move toward nondriving position.

Claim 13

In a tractor or the like having a frame, motor-driven pulley, a wheel-driving pulley, a variable-speed sheave assembly, the axes of said pulleys and sheave assembly being generally parallel, V-belt means operatively interconnecting said pulleys and sheave assembly and adapted to drive the wheel-driving pulley from the motor-driven pulley at a variable speed dependent upon the movement of the axis of the sheave assembly relative to the respective axes of the said pulleys through a range of movement between low-speed position and high-speed position, the combination of an arm member carrying said sheave assembly and pivotally swingable about a pivot point on said frame to swing the sheave assembly through said range of movement, connecting means operatively connecting said arm member and frame to permit swinging of the arm member on said pivot point and to permit longitudinal movement of the arm member relative to said frame for moving the said sheave assembly between V-belt tensioning position and V-belt loosening position, yieldable biasing means biasing the arm member in a longitudinal movement toward V-belt tensioning position, a bar having a first end and a second end, the bar being pivotally carried by said frame to swing said first and second ends in opposite directions, operating means operatively connected to said bar to swing said first and second ends in opposite directions, link means interconnecting said bar and arm member to swing said sheave assembly carried by the arm member through said range of movement between low-speed position and high-speed position, said link means also being arranged relative to the arm member to move said arm member against the bias of the yieldable biasing means longitudinally of the arm member to swing the said sheave assembly beyond said low-speed position in an arc about the axis of said wheel-driving pulley to said V-belt loosening position.

Claim 14

In a tractor or the like having a frame, motor-driven pulley, a wheel-driving pulley, a variable-speed sheave assembly, the axes of said pulleys and sheave assembly being generally parallel, V-belt means operatively interconnecting said pulleys and sheave assembly and adapted to drive the wheel-driving pulley from the motor-driven pulley at a variable speed dependent upon the movement of the axis of the sheave assembly relative to the respective axes of the said pulleys through a range of movement between low-speed position and high-speed position, the combination of an arm member carrying said sheave assembly and pivotally swingable about a pivot point on said frame to swing the sheave assembly through said range of movement, connecting means operatively connecting said arm member and frame to permit swinging of the arm member on said pivot point and to permit longitudinal movement of the arm member relative to said frame for moving the said sheave assembly between V-belt tensioning position and V-belt loosening position, yieldable biasing means biasing the arm member in a longitudinal movement toward V-belt tensioning position, a bar having a first end and a second end, the bar being pivotally carried by said frame to swing said first and second ends in opposite directions, operating means operatively connected to said bar to swing said first and second ends in opposite directions, link means interconnecting said bar and arm member to swing said sheave assembly carried by the arm member through said range of movement between low-speed position and high-speed position, said link means also being arranged relative to the arm member to move said arm member against the bias of the yieldable biasing means longitudinally of the arm member to swing the said sheave assembly beyond said low-speed position in an arc about the axis of said wheel-driving pulley to said V-belt loosening position.

Claim 15

The combination as claimed in claim 11 and in which said operating means has a first actuating portion connected to said one end of the said bar and a second actuating portion connected to said second end of the said bar, said actuating portions being separably operable whereby actuation of one portion swings the bar in one direction and actuation of the other portion swings the bar in an opposite direction, the swinging of the bar moving the arm member through the link means to move the sheave assembly between high-speed and low-speed positions and between V-belt tensioning position and V-belt loosening position.

Claim 16

The combination as claimed in claim 11 and including braking means for the tractor operatively connected to said bar to actuate the braking means by the swinging of said bar, and including resilient means urging said braking means toward braking position upon said bar being swung sufficiently toward a stopping position to cause the link means to so move the arm member as to swing the sheave assembly to said V-belt loosening position.

Claim 17

The combination as claimed in claim 13 and including a toggle-joint mechanism adapted alternatively to hold the operating means in locked position for maintaining said bar in said stopping position and to permit the operating means to move for swinging of said bar, said toggle-joint mechanism being resiliently urged by said resilient means to said locked position upon the toggle-joint mechanism being manually placed in locked position by the operating means swinging the said bar to actuate the locking means to locked position.

Claim 18

Variable speed drive means for a tractor having a frame, a motor-driven pulley, a wheel-driving pulley, a variable-pitch sheave assembly having a plurality of sheaves having pitches variable relative to each other, said pulleys and said sheave assembly having generally parallel axes spaced from each other, V-belt means reeved about said pulleys and sheave assembly in a manner to vary the pitches of the sheaves of said assembly relative to each other and thus modify the drive ratio of said pulleys upon shifting of the position of the axis of the sheave assembly relative to the respective axes of the said pulleys in a range between low-speed position and high-speed position, comprising in combination first means carrying said sheave assembly for shifting the axis thereof through a first range of movement in an arcuate path about a pivot point between low-speed position and high-speed position relative to said pulleys, said first means including yieldable tensioning means urging said sheave assembly relative to said pivot point in a direction to maintain driving tension on said V-belt means through said first range of movement, and second means operatively connected to said first means for shifting the axis of the sheave assembly through a second range of movement in another path converging with said arcuate path toward and away from said pivot point between said low-speed position and in inoperative position, said second means having such length of stroke relative to the effective length of the V-belt means between the axes of the pulleys and sheave assembly and being so directed relative to said first range of movement that the sheave assembly moved by the second means in the second range of movement away from said low-speed position opposes said yieldable tensioning means and the sheave assembly under the restraint of the V-belt means reeved about one of the said pulleys moves against the urging of the yieldable tensioning means toward an inoperative position to relax the tension of the V-belt means reeved about the other of the said pulleys, said V-belt means being under driving tension in said low-speed and high-speed positions of the sheave assembly and intermediate said positions, and being in relaxed nondriving tension in said inoperative position of the sheave assembly, said second range of movement being successive to said first range of movement, and occurring only, after the second means has moved the axis of the sheave assembly from said first range of movement beyond said low-speed position in a direction away from said high-speed position.

Claim 19

Variable speed drive means for a tractor having a frame, a motor-driven pulley, a wheel-driving pulley, a variable-pitch sheave assembly having a plurality of sheaves having pitches variable relative to each other, said pulleys and said sheave assembly having generally parallel axes spaced from each other, V-belt means reeved about said pulleys and sheave assembly in a manner to vary the pitches of the sheaves of said assembly relative to each other and thus modify the drive ratio of said pulleys upon shifting of the position of the axis of the sheave assembly relative to the respective axes of the said pulleys in a range between low-speed position and high-speed position, comprising in combination first means carrying said sheave assembly for shifting the axis thereof through a first range of movement in an arcuate path about a pivot point between low-speed position and high-speed position relative to said pulleys, said first means including yieldable tensioning means urging said sheave assembly relative to said pivot point in a direction to maintain driving tension on said V-belt means through said first range of movement, and second means operatively connected to said first means for shifting the axis of the sheave assembly through a second range of movement in another path converging with said arcuate path toward and away from said pivot point between said low-speed position and in inoperative position, said second means having such length of stroke relative to the effective length of the V-belt means between the axes of the pulleys and sheave assembly and being so directed relative to said first range of movement that the sheave assembly moved by the second means in the second range of movement away from said low-speed position opposes said yieldable tensioning means and the sheave assembly under the restraint of the V-belt means reeved about one of the said pulleys moves against the urging of the yieldable tensioning means toward an inoperative position to relax the tension of the V-belt means reeved about the other of the said pulleys, said V-belt means being under driving tension in said low-speed and high-speed positions of the sheave assembly and intermediate said positions, and being in relaxed nondriving tension in said inoperative position of the sheave assembly, said second range of movement being successive to said first range of movement, and occurring only, after the second means has moved the axis of the sheave assembly from said first range of movement beyond said low-speed position in a direction away from said high-speed position.

Claim 20

The combination claimed in claim 15 and including braking means for braking said tractor, and third means operatively connected to said second means for actuating the braking means upon moveMent of the axis of the sheave assembly in said second range of movement toward said inoperative position of the sheave assembly, and for releasing the braking means upon movement of the second means in said second range of movement toward said low-speed position of the sheave assembly.

Claim 21

The combination claimed in claim 16 and in which said third means includes fourth means movable to locking position for releasably and jointly locking said sheave assembly in inoperative position and said third means in brake-actuated condition, said fourth means upon being moved to said locking position being biased to remain in locking position, said fourth means being manually releasable from said locking position to permit the said sheave assembly to be moved in said second range of movement toward low-speed position.

Claim 22

In a tractor having a frame, a motor-driven pulley, a wheel-driving pulley, V-belt means operatively connecting said pulleys, and including a sheave assembly, said sheave assembly having a plurality of sheaves rotatably mounted on its axis and having pitch diameters variable in inverse ratio to each other by said V-belt means upon varying the spacing of the axis of the sheave assembly relative to the respective axes of said pulleys, said sheave assembly being operatively disposed in said V-belt means for changing the drive ratio of said pulleys by movement of the sheave assembly to variably space the axis of the sheave assembly relative to the respective axes of said pulleys, the combination of an arm member pivotally carried by a pivot pin carried by said frame, said arm member carrying said sheave assembly to swing in a range of movement between high-speed position and low-speed position, said arm member having an elongated slot therein accommodating said pivot pin to permit the arm member to be moved longitudinally toward and away from the pivot pin, a spring interconnecting the frame and arm member and biased to urge said arm member in a direction resiliently holding the sheave assembly away from said pivot pin, a bar pivotally carried intermediate its ends to said frame, a first rod interconnecting said arm member and a first end of said bar to swing the arm member on said pivot pin in accordance with pivotal swinging of said bar, a braking mechanism for said tractor, a second rod connected to a second end of said bar and to said braking mechanism to operate the braking mechanism in accordance with the pivotal swinging of said bar, and a pair of manually operable actuators each independently connected to one of said rods arranged to provide that manual actuation of a first of said actuators in a first general direction moves the first rod, first end of the bar and arm member in a direction to swing the said sheave assembly toward high-speed position and the second actuator and second rod connected thereto is simultaneously moved in an opposite direction by said bar and the braking mechanism is moved by the second rod to inoperative position, and arranged to provide that manual actuation of a second of said actuators in said first general direction moves the second rod and second end of the bar in a direction to swing said sheave assembly toward low-speed position and the first actuator and first rod connected thereto is simultaneously moved in said opposite direction by said bar, the continued successive actuation of said second actuator in said first general direction moving the sheave assembly past said low-speed position to cause the sheave assembly carried by said arm member to move toward said pivot pin in said slot against the bias of said spring to loosen the driving tension on said V-belt means and simultaneously causing the braking mechanism to be moved by said second rod to braking position.

Claim 23

In a tractor having a frame, a motor-driven pulley, a wheel-driving pulley, V-belt means operatively connecting said pulleys, and including a sheave assembly, said sheave assembly having a plurality of sheaves rotatably mounted on its axis and having pitch diameters variable in inverse ratio to each other by said V-belt means upon varying the spacing of the axis of the sheave assembly relative to the respective axes of said pulleys, said sheave assembly being operatively disposed in said V-belt means for changing the drive ratio of said pulleys by movement of the sheave assembly to variably space the axis of the sheave assembly relative to the respective axes of said pulleys, the combination of an arm member pivotally carried by a pivot pin carried by said frame, said arm member carrying said sheave assembly to swing in a range of movement between high-speed position and low-speed position, said arm member having an elongated slot therein accommodating said pivot pin to permit the arm member to be moved longitudinally toward and away from the pivot pin, a spring interconnecting the frame and arm member and biased to urge said arm member in a direction resiliently holding the sheave assembly away from said pivot pin, a bar pivotally carried intermediate its ends to said frame, a first rod interconnecting said arm member and a first end of said bar to swing the arm member on said pivot pin in accordance with pivotal swinging of said bar, a braking mechanism for said tractor, a second rod connected to a second end of said bar and to said braking mechanism to operate the braking mechanism in accordance with the pivotal swinging of said bar, and a pair of manually operable actuators each independently connected to one of said rods arranged to provide that manual actuation of a first of said actuators in a first general direction moves the first rod, first end of the bar and arm member in a direction to swing the said sheave assembly toward high-speed position and the second actuator and second rod connected thereto is simultaneously moved in an opposite direction by said bar and the braking mechanism is moved by the second rod to inoperative position, and arranged to provide that manual actuation of a second of said actuators in said first general direction moves the second rod and second end of the bar in a direction to swing said sheave assembly toward low-speed position and the first actuator and first rod connected thereto is simultaneously moved in said opposite direction by said bar, the continued successive actuation of said second actuator in said first general direction moving the sheave assembly past said low-speed position to cause the sheave assembly carried by said arm member to move toward said pivot pin in said slot against the bias of said spring to loosen the driving tension on said V-belt means and simultaneously causing the braking mechanism to be moved by said second rod to braking position.

Claim 24

The combination claimed in claim 18 and including a lost-motion connection between said second rod and the second end of said bar, said lost-motion connection including a resilient member urging said second rod in a direction to urge the brakinG mechanism to an inoperative position upon the second actuator and second rod swinging said bar sufficiently far in a direction to exert a baising tension on the said resilient member.

Claim 25

The combination claimed in claim 19, and including a manually operable locking mechanism associated with said second rod to hold said second rod in a position to hold the braking mechanism in braking position, the locking mechanism being resiliently aided by the resilient member to be held in locked position and to be manually releasable against the bias of the resilient member to permit the second rod to move the braking mechanism to inoperative position.