Abstract: A hydraulic device having two hydraulic actuators, in particular a motor and a double-acting jack, each having two couplings for the entry and/or the exit of a control fluid. Two pipes are coupled to the two actuators and designed so that one conveys a pressurized fluid to a respective coupling of each actuator while the other discharges the fluid to the other respective coupling, and vice versa, in such a way that the jack can be controlled to selectively produce a movement in opposite directions. A selective reversing gate reverses, between the two pipes, the supplying of pressurized fluid and the discharging of the fluid so as to control the direction of the movement of the jack.
Abstract: A system and method for controlling an electro-hydraulic valve arrangement to provide make-up fluid to a hydraulic actuator are disclosed. The system includes an electro-hydraulic valve arrangement actuated by a control lever and disposed between a pump having a stand-by pressure and a hydraulic actuator. A pressure, representative of the fluid in the hydraulic actuator, is sensed and compared to the stand-by pressure of the pump. The control of the control lever over the electro-hydraulic valve arrangement is overridden when the difference between the pump stand-by pressure and the pressure of the fluid in the hydraulic actuator is greater than a predetermined pressure limit.
Type:
Grant
Filed:
August 28, 2001
Date of Patent:
July 29, 2003
Assignee:
Caterpillar Inc
Inventors:
Stephen Victor Lunzman, Xiaodong Huang, Kirk Stephen Shively, Bradford Jay Holt
Abstract: An inclined-axis variable displacement unit has an output shaft (1), mounted in a housing (4), and a cylinder block (10), the cylinder block (10) being connected to the output shaft (1) via a synchronizing articulation (13), and via working pistons (11) which can be displaced in the cylinder block (10), and the cylinder block (10) being mounted in a pivoting body (5) which can be pivoted in relation to the axis of the output shaft, it being the case that the pivoting body (5) is in the form of an open vessel, and the cylinder block (10) is arranged in the opening of the pivoting body.