Hydraulic drive system
US5873245A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 7, 1997 |
| Grant date | Feb 23, 1999 |
| Priority date | — |
| Expiry date | Mar 7, 2017 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF15B2211/7135
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Pressure adjusting valves (9A, 9B) control outlet pressures of variable throttle portions (8a) of directional control valves (8A, 8B) of closed center type to be kept substantially equal to a maximum load pressure detected by a detecting line (13). A variable throttle valve (40) and a pressure adjusting valve (41) are disposed in a bypass line (5) branched from a pump supply line (3) for controlling an outlet pressure of the variable throttle valve (40) to be also kept substantially equal to the maximum load pressure. The variable throttle valve (40) has an opening area controlled to be reduced with an increase in the input amount by which a control lever unit is operated, and a pump delivery rate is controlled by a tilting control device (2n) to become a flow rate corresponding to the input amount of the control lever unit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.