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US 6,648,576 B1Granted
Hydraulic system and method of operating same
AssigneeMcClain Industries
InventorsCharles A. Duell, Thomas E. Pfeifer
Life of this patent
Estimating the term…
Abstract
An improved hydraulic system and method of operating same for waste collection vehicles is provided where a closed center valve in conjunction with a positive displacement pump is used without the need for increasing engine RPM, thus significantly reducing vehicle noise during operation of the hydraulic system.
Claims3
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.
5 more elements
A method of operating a hydraulic system in a rear loading waste collection vehicle comprising, in combination,
- a) providing an engine in a rear 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.
5 more elements
A method of operating a hydraulic system in a waste collection vehicle designed to collect recyclables comprising, in combination,
- a) providing an engine in a waste collection vehicle designed to collect recyclables 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.
5 more elements
Dependencies are inferred from the claim text.