The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 13, 1989
Filed:
Aug. 17, 1988
Steven H Johnson, Dubuque, IA (US);
Lary L Williams, Dubuque, IA (US);
Deere & Company, Moline, IL (US);
Abstract
An excavator has a number of different hydraulically powered functions that are controlled by a closed center hydraulic system that features a pair of variable displacement, engine driven hydraulic pumps, the displacement of which is responsive to the demands of the system. The flow to the various hydraulic motors is controlled by pilot operated load sensing control valves that direct fluid pressure to a load sensing line when one of the hydraulic motors in the system is being operated. The load sensing line is connected to the control system of the pumps to place the pumps in stroke when a flow of pressurized fluid is required. The flow of the load sensing pressure to the controls for one of the pumps can be optionally disconnected to place said pump in a standby condition and thereby reduce the flow capacity of the hydraulic system at the option of the operator. The load sensing line is also connected to a pressure actuated switch that closes when pressure in the line falls below a predetermined point, which occurs when none of the hydraulic motors are being actuated. The closed switch provides electric power to a solenoid through a time delay circuit so that the solenoid shifts the throttle control level on the excavator engine to its idle condition at a delay after the hydraulic pressure demand falls below the predetermined level.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile