Hydraulic control system for a tree felling unit
US4039009A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 20, 1976 |
| Grant date | Aug 2, 1977 |
| Priority date | — |
| Expiry date | Aug 20, 1996 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/2496
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
At the end of a crane arm on a base vehicle is fixed a frame, the inclination of which is controlled by double-acting hydraulic cylinders, and which supports hydraulically operated grip arms and a cutting unit. The frame is moved with an estimated inclination against a tree, and the grip arms urge the frame into conformance with the actual inclination of the tree, thereby inducing strains in the tree as well as the firmly based crane arm. A valve connecting the inlet and outlet of each hydraulic cylinder is momentarily opened from its hitherto closed position, so that the fluid in the cylinder is forced to equalize under the strains from the biased tree which consequently will be relieved from tension before cutting, otherwise resulting in cracks in the root end of the tree.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.