Patent ID: 6059534
Filing Date: 2000-05-09
Classification: F16H

Abstract:
A control system for an hydraulic drive, the drive comprising first and second motors (4,6) connectable to the input side of a gearbox (8), the output side of the gearbox being connected to a load whereby each of said motors (4,6) can apply a driving force to the load, one of said motors (6) being capable of selective connection to and disconnection from the load by means of a clutch (10) independently of the other motor (4) while the load is being driven, the control system being characterised by a hydraulic pump (20) driven by an output from the gearbox (8) such that the pump (20) is rotated at a speed which is proportional to the speed at which the other hydraulic motor (4) is operating, pressure-sensing means (24) for detecting the pressure of fluid displaced by said pump (20), and control means (28) for controlling the flow of fluid to an hydraulic actuator (18) interconnected with, to enable selective actuation of, the clutch (10), the arrangement being such that, when the pressure sensing means (24) detects a pressure associated with a predetermined rotational speed of the other motor (4) at which the drive from the one motor (6) becomes redundant, the control means (28) operate the hydraulic actuator (18) to disconnect the one motor (6) from the gearbox (8).