Abstract: A hydrostatic transmission constructed so that a check valve and a relief valve are made as compact as possible to supply oil to a closed circuit for connecting a hydraulic pump and a hydraulic motor, and to regulate maximum pressure in the closed circuit. A check valve and a relief valve are contained in a valve casing. A valve body of the relief valve is disposed opposite to a valve body of the check valve. A relief spring of the relief valve is retained by a cover detachably mounted to an open end of the valve casing, thereby facilitating pressure setting of the relief valve. The valve body of the relief valve is contained in a relief valve casing slidably disposed in the valve casing. A plunger, capable of urging the check valve in the opening direction via the relief valve casing, is provided in the cover, thereby enabling the check valve to be manually opened.

Abstract: A vehicle drive transmission includes a hydrostatic transmission (14) which comprises a hydraulic motor (16) of a variable displacement type. Swash plate (29) of this motor is displaced from its neutral position in one direction in a stepwise manner to plural angular positions. The motor is used for setting one of plural speed ranges or low-speed and high-speed ranges of vehicle within which vehicle speed can be changed in a non-stepwise manner by a hydraulic pump (15) having a non-stepwisely displaceable swash plate (28). Output shaft (18) driven by the motor is connected to rear wheels (2) for a constant drive thereof through a mechanical transmission mechanism (21) and to front wheels (1) for a selective drive thereof through a clutch mechanism (26; 126; 226). The clutch mechanism preferably includes a one-way clutch (85) for providing a selective drive mode in which front wheels are additionally driven automatically when slipping of the rear wheels is caused during the two wheel-drive condition.

Abstract: A variable displacement type hydraulic system is contained in a housing. A guide is provided on an axis of slanting movement of a swash plate. The guide is fitted into an inner ring of a roller bearing. The roller bearing is fitted into a groove formed at an inner wall of the housing and a groove formed at a cylinder block mounting surface of a center section so as to be fixedly positioned in the housing. In accordance with the invention, sliding resistance of the swash plate is reduced to improve the ability of the swash plate to return to the neutral position.

Abstract: In a valve mechanism for controlling oil pressure in an oil path (13) connecting between a hydraulic pump (11) and motor (12) of a hydrostatic transmission (10), a differential piston (23) serving as a relief valve member for gradually increasing the oil pressure has a larger pressure-applied surface area at the side opposite to the oil path than at the side of this path. A throttled oil passage (24) is provided for conducting oil pressure in the path to the larger surface area. The piston is biased by a valve spring (25) through a control piston (26). A receiving member (27) for the spring and a stopper member (28) for the control piston are provided such that they are adjustable in position independently of each other. By this, the manner of increasing the oil pressure may be adjusted in a large variety. The valve mechanism also serves as a relief valve for excluding a possible, excessively high pressure.

Abstract: A steering apparatus for a vehicle which is provided at part of a handle shaft of a handle with a steering mechanism so that a steering cylinder expands and contracts to perform hydraulic steering and, even when a hydraulic system is in trouble, the steering mechanism serves as a speed reduction mechanism, thereby enabling mechanical steering.

Abstract: A steering apparatus of both mechancial and hydraulic systems for a vehicle which devised the conventional steering box itself so as to attach a steering hydraulic valve directly to a steering case at the steering gear box, thereby being steerable by the steering gear box.

Abstract: A hydraulic steering system for use in four-wheel running vehicles or the like of small size and low horsepower. The steering system and a hydraulic system for lifting a working implement are both operable by a single hydraulic pump without the necessity of using a variable displacement hydraulic pump or providing two hydraulic pumps for the two systems. The steering system is operable by an engine of low horsepower.