Patent ID: 6648576
Filing Date: 2003-11-18
Classification: B65F

Abstract:
A method of operating a hydraulic system in a side loading waste collection vehicle comprising, in combination,a) providing an engine in a side loading waste collection vehicle having a varying RPM that is mechanically connected to a fixed displacement pump having a variable piston stroke; b) activating an operator control in communication with a closed center valve having one or more valve spools, where the closed center valve prevents flow of hydraulic fluid through the valve when the spools are in a neutral position; c) changing position of at least one valve spool from a neutral position in response to activating the operator control and causing hydraulic fluid to flow to at least one hydraulic cylinder; d) pressurizing hydraulic fluid by increasing the stroke of the fixed displacement pump in response to a signal received from a pump controller in fluid communication with the closed center valve, where the pump stroke is increased without increasing engine RPM; e) sensing a load applied to the at least one hydraulic cylinder and transmitting the sensed load to the pump controller; f) increasing or decreasing the piston stroke of the pump independently of engine RPM to change volumetric hydraulic fluid flow in response to the sensed load transmitted to the pump controller; and g) destroking the pump to reduce the volumetric hydraulic fluid flow to achieve stand-by pressure when no load on the at least one hydraulic cylinder is sensed or the valve spools are in a neutral position.