SYSTEM FOR CONTROLLING REVOLUTION FREQUENCY OF PRIME MOVER IN HYDRAULICALLY DRIVEN VEHICLE

摘要

The system comprises a hydraulic pump (1) driven by an engine (21); a hydraulic motor (4) for running, driven by oil discharged from the hydraulic pump (1) during running; an actuator (52) for working, driven by oil discharged from the hydraulic pump (1) during working; a running pedal (6) for controlling a running speed in accordance with a manipulated variable during running; a reduced speed determining means (33) for determining the reduced depression of the running pedal (6); and a revolution frequency controller (33). The revolution frequency controller (33) performs a regular control for increasingly or decreasingly controlling the revolution frequency of the engine in accordance with the depth of the depression of the running pedal (6), and slow-down control for decreasingly controlling the revolution frequency of the engine to match the reduced depth of the depression when the depth of the depression is determined to be reduced. Then, when the revolution frequency of the engine is to be adjusted by the running pedal (6) during working, even if the depth of the depression of the running pedal (6) is reduced, the slow-down control is prohibited.