US 5,377,774 AGranted

Variable speed drive system

AssigneeHoffco, Inc.

InventorThomas H. Lohr

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Abstract

A variable speed drive system for use with a self-propelled device is coupled by a belt to an engine which is mounted to the device. The variable speed drive system includes a variable pitch pulley held in spaced-apart relation to the drive shaft by a fixture and rotates about the drive shaft between a first position proximal to the engine and a second position distal to the engine. In the first position, the drive system is disengaged from the engine and the speed of the self-propelled device is zero, the belt being slack and providing no drive force to the drive system. In the second position, the drive system is moved a maximum amount about the drive shaft and is positioned to achieve a maximum speed. The drive system can also assume any intermediate position between the first and second positions, with the speed of the self-propelled device being determined by the amount of movement about the drive shaft toward the second position. A speed control lever and a control cable assembly are included for limiting the amount of movement of the drive system about the drive shaft to control the speed of the self-propelled device

Claims25

Dependent claims

A variable speed drive system for a self-propelled device having a frame, an engine coupled to the frame, a drive pulley rotated by the engine, a handle coupled to the frame, a drive wheel assembly coupled to the frame for propelling the self-propelled device, and a bail pivotably coupled to the handle for movement between an engine-idling position away from the handle and a device-moving position adjacent to the handle, the system comprising

a variable pitch pulley,
shaft means for rotatably supporting the variable pitch pulley,
a drive belt engaging the drive pulley and the variable pitch pulley,
means for turning the drive wheel assembly to propel the self-propelled device in response to rotation of the variable pitch pulley, the turning means including an endless chain engaging the shaft means and the drive wheel assembly and lying in tension, and
means for moving the shaft means and the variable pitch pulley relative to the frame from a disengaged position lying a first distance away from the drive pulley and relaxing tension on the drive belt engaging the drive pulley and the variable pitch pulley to block rotation of the variable pitch pulley in response to rotation of the drive pulley by the engine to an engaged position lying a greater second distance away from the drive pulley and tensioning the drive belt to cause rotation of the variable pitch pulley in response to rotation of the drive pulley by the engine in response to movement of the bail from the engine-idling position to the device-moving position without varying tension applied to the endless chain turning the drive wheel assembly in response to rotation of the variable pitch pulley, the moving means being coupled to the bail for movement therewith relative to the frame.

2 more elements

a transmission including a fixture having first and second ends, a variable pitch pulley unit rotatably coupled to the first end of the fixture, pivot means for pivotably coupling the second end of the fixture to the frame so that the fixture and the variable pitch pulley unit is pivotable relative to the frame between a forward-leaning position and a rearward-leaning position,
a drive belt engaging the drive pulley and the variable pitch pulley unit and pivoting the fixture relative to the frame to draw the variable pitch pulley unit to the forward-leaning position,
means for turning the drive wheel assembly to propel the self-propelled device at a certain speed only in response to tensioning the drive belt caused by pivoting movement of the fixture and variable pitch pulley unit relative to the frame and away from the forward-leaning position so that the engine moves the drive belt to rotate the variable pitch pulley unit, and
cable means interconnecting the first end of the fixture and the bail for pivoting the fixture and variable pitch pulley unit from its forward-leaning position toward its rearward-leaning position in response to movement of the bail from its engine-idling position toward its device-moving position so that the drive belt engaging the engine and the variable pitch pulley unit is moved to rotate the variable pitch pulley unit and is tensioned to change the pitch of the variable pitch pulley unit causing a change in the speed of the self-propelled device.

1 more element

Dependencies are inferred from the claim text.