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:
Apr. 20, 1993
Filed:
Jul. 01, 1991
Hitachi Construction Machinery Co., Ltd., Chiyoda, JP;
Abstract
A first hydraulic circuit comprises a variable displacement hydraulic pump driven by a prime mover, a variable displacement hydraulic motor connected in a closed circuit to the variable displacement hydraulic pump, and a displacement control means for controlling a displacement of the variable displacement hydraulic motor. A second hydraulic circuit comprises a hydraulic pump driven by the prime mover, and drives a loader attachment. A displacement limitation means limits the maximum value of the displacement of the variable displacement hydraulic motor in accordance with a load pressure of the second hydraulic circuit. For example, the displacement limitation means reduces the maximum value of the displacement of the variable displacement hydraulic motor in proportion to the pressure in the second hydraulic circuit. The motor torque is controlled by directly adjusting the displacement of the motor, and a load of the hydraulic motor can thus be stably controlled.