High lift hydraulic system for an excavator
US4218837A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 21, 1978 |
| Grant date | Aug 26, 1980 |
| Priority date | — |
| Expiry date | Aug 21, 1998 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE02F9/2203
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
The disclosure relates to an apparatus for increasing the lifting capacity of the boom of an excavator to lift heavy objects, while conjointly disabling the hydraulic circuit used for normal digging operations to avoid damaging the excavator. The apparatus includes a manually operated pilot valve for selectively applying a control fluid pressure to a relief valve for a hoist cylinder and a to relief valve for a digging bucket cylinder. The control fluid pressure biases the hoist relief valve to remain closed at hydraulic pressures above the normal relief pressure of the valve, and conjointly biases the bucket relief valve to open, thereby disabling the bucket.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.