HYDRAULICALLY DRIVEN CRAWLER VEHICLE

摘要

This invention provides a hydraulically driven crawler vehicle in which pilot pressure for controlling the discharge of right and left variable displacement pumps is produced in response to the engine speed by throttle valves disposed in the discharge oil circuit of a fixed displacement pump, variable throttle valve in a branch circuit each installed in a pilot circuit for controlling the right and left crawlers is operated by a cam rotated by the steering wheel, and when the steering wheel is turned exceeding a certain angle, a direction change-over solenoid valve of variable displacement pump at the steering wheel turning side is energized to the reverse side so that the right and left crawlers are driven in the reverse direction to each other. Also, this invention provides a hydraulically driven crawler vehicle in which the oil pressure to a swash plate angle control cylinder which changes the angle of swash plate in the variable displacement pump producing oil pressure to the motor for traveling is controlled by feeding back the actual angle of swash plate so that the angle of swash plate corresponds to the command pressure based on the engine speed.