Unipat Ag

Unipat Aktiengessellschaft

Quadrant Drive Bv

George Duncan Arnold

Christian Helmut Thoma

Arthur Atholl Blair

Dale I Havens

Roland L Von Kaler

Norman E Jolliff

John C Carden

Panayotis C Dimitracopoulos

An axle assembly for use in lawn tractors, pedestrian walk-behind mowers and snow blowers in the form of a housing having an internally disposed hydrostatic transmission and speed reducing gearing. An input shaft supported in the housing for driving a variable-displacement hydraulic pump of the hydrostatic transmission, the pump fluidly coupled to a fixed-displacement hydraulic motor of the hydrostatic transmission, and where the motor is drivingly connected through the speed reducing gearing to an output axle shaft or shafts. A mechanical differential disposed within said housing for applications requiring differential speeds of said axle output shafts. The housing being formed by three housing members and joined together along a substantially planar and horizontally peripheral seam formed there between such that two of said housing members are to one side of said seam and join with the third housing element. Two internal chambers formed by the three housing elements where one chamber contains the hydrostatic transmission and the other chamber contains the speed reducing gearing. A connecting shaft spanning between the chambers to provide the power transmission link between the hydrostatic transmission and the speed reducing gearing.

Hydrostatic transaxles with 2 chambers defined by three housing parts

A hydrostatic transmission having a housing for an internally disposed variable-displacement hydraulic pump and fixed-displacement hydraulic motor, a framework for supporting the hydraulic pump and motor components within said housing in a manner whereby the loads generated by the pressure medium flowing between pump and motor are absorbed into the framework. The framework to support a pintle-valve which as the fluid coupling means between pump and motor.

Radial piston hydrostatic transmission of the type incorporated into a

Hydraulic radial piston machines

A hydrostatic transaxle axle assembly for a vehicle such as a grass mowing lawn or garden tractor comprising a housing for an internally disposed hydrostatic transmission having a variable-displacement hydraulic pump fluidly connected to a fixed-displacement hydraulic motor, the hydraulic motor being connected by differential gearing to axle shafts supported in the housing. The housing is formed by three housing members, two of which are preferably separable on a parting plane coincident with the longitudinal axes of the axle shafts. One of the housing members being provided with an opening to allow a portion of one of the other housing members to extend through, and where the extending housing member contains within its interior a number of internal fluid passages for fluidly connecting the hydraulic pump to the hydraulic motor. This construction allows for improved cooling of the power transmitting fluid flowing between the pump and motor and simplifies manufacture of the transaxle such that the bulk or all the machining operations can be carried out in only one of the three housing elements, this housing member being the smallest of the three which can be completed using a comparatively smaller sized CNC machining-center than would otherwise be the case. The two remaining housing elements may be used in an as cast or supplied condition.

Hydrostatic transaxle

A radial piston hydrostatic machine having an outer housing structure comprising at least two housing elements connectable together along a parting-plane arranged perpendicular to the rotational axis of said drive-shaft to define an internal chamber, a drive-shaft supported in the housing to drive the cylinder-barrel, the cylinder-barrel having a number of radial cylinders, each cylinder containing a piston such that the pistons can bear on the track-ring, fixed abutment means in the housing and disposed radially adjacent the track-ring for resisting the action of the pistons on the track-ring and suppressing vibration emanating from the track-ring.

Hydrostatic piston machines

A radial piston hydrostatic machine disposed in a housing, a drive shaft supported in the housing and connecting through bevel pinion and gear to transmit rotation of the shaft to a cylinder barrel. The cylinder barrel provided with generally radial cylinder bores supporting pistons and mounted to rotate on a stationary ported pintle valve fixed to said housing. The cylinder barrel having an axially extending projection to support the bevel gear in spaced relationship with the end of said cylinder barrel, the bevel gear rotating with said cylinder barrel and drivingly connected to said bevel pinion. Fluid bearing means provided on the outer cylindrical surface of said pintle valve to provide a pressure field under said axially extending projection in order to counter any deflection of said bevel gear.

Bevel gear support with fluid bearings for radial piston hydrostatic

A transaxle driving apparatus for a self-propelled vehicle such as a grass-mowing lawn tractor, the transaxle comprising a two-piece housing structure forming an internal chamber for encapsulation of a hydrostatic machine and associated reduction gearing. The hydrostatic machine may comprise in one form a single hydrostatic pump driven by an input shaft rotatably supported in the housing, and fluidly coupled to two hydrostatic motors. In a modified form, the hydrostatic machine may comprise two hydrostatic motors fluidly coupled to a pumping source remotely mounted outside the transaxle.

Variable speed transaxle

A friction drive unit for use within a transaxle driving assembly in self-propelled vehicles such as grass-mowing lawn tractors, the transaxle comprising a two-piece housing structure forming a number of internal chambers for the encapsulation of the friction drive unit, associated reduction gearing and a mechanical differential. The friction drive may comprise as input members, a pair of driver wheels operatable against a larger driven disc wheel acting as the output member, such that only one driver wheel can be engaged to the driven wheel at any one time, and where the direction of vehicle motion depends on which one of the two driver wheels is in contact with the driven wheel. Each of the driver wheels is subjected to continuous rotation from an input drive shaft and are operatively displaced along the shaft by means of respective sliding yoke means. The output from the driven wheel is connected to the transaxle output shafts by means of high ratio gear reduction means.

Friction drive transmission

A transaxle housing is provided for a small-sized vehicle such as a grass-mowing lawn tractor and encloses an internally located hydrostatic transmission in association with speed reducing gearing and mechanical differential for reasons of compactness and simplicity of manufacture. The axle housing comprises two members connected together alone a parting plane to define a number of internal chambers, at least one chamber used to enclose the hydrostatic transmission and remaining chambers enclosing speed reducing gearing and differential. One housing element is provided with a vertical input shaft which is operatively connected through bevel gearing to a hydraulic pump, the pump mounted perpendicular and fluidly coupled to a hydraulic motor, the rotary axis of the hydraulic motor being coincident with the parting plane of the housing and parallel to the rotating axes of the half shafts of the transaxle. The bevel gearing being located within either the chamber enclosing the hydrostatic transmission or within one of the remaining chambers enclosing the reduction gearing and differential.

A transaxle driving apparatus for a small-sized vehicle such as a grass-mowing lawn tractor, formed from a two-piece housing to encapsulate a hydrostatic transmission with associated reduction gearing and mechanical differential member. One housing element is provided with a vertical input shaft which is drivingly engaged to the hydraulic pump of the hydrostatic transmission by means of bevel gearing. A hydraulic motor of the hydrostatic transmission is provided with a motor shaft, a speed reduction shaft, and a differential gear unit attached to the axle shafts, all shafts other than the input shaft being disposed horizontally along the plane containing the longitudinal axis of the transaxle for economy and compactness.

The present invention is a neutral shifting mechanism for a hydrostatic transmission. A motor track ring has a groove and cam slot for receiving a control rod of the transmission, with the control rod having a cam portion for engaging the cam slot to lock the track ring in a position concentric with the pintle of the hydraulic motor, i.e. a neutral position. In the normal position, the cam portion positions the track ring eccentrically, allowing a speed control shaft to shift the hydrostatic transmission by pivoting the pump track ring about the control rod.

Neutral shifting mechanism for hydrostatic transmission

A hydrostatic machine includes a casing (10) containing a rotary member (12) having radial cylinders (24) each with a piston (25) engaging a track ring (27). The member (20) is coupled to an external shaft (13) via reduction gearing (43,44) which also acts as a gear pump. This can be used to supply external power take-off fluid circuits, or an attached oil filter (64) or internal bearings (47,57) or make-up fluid for the machine via valve (42).

Rotary hydrostatic machines or transmissions

A rotary radial piston pump or motor has a cylinder barrel rotating on a fixed pintle with a fluid exit at the fixed end of the pintle and an inlet at the opposite free end. A fluid impeller boosts the pressure entering the inlet and a filter prevents dirt entering. When applied to a hydrostatic transmission with pump and motor on a common pintle a pair of opposed non-return valves admit make-up fluid at one end of the pintle and a pressure relief valve provides overload relief at the other end of the pintle.

Growing community of inventors

Jersey, United Kingdom

George Duncan Arnold