Tractor hitch position control system
US4132272A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 30, 1977 |
| Grant date | Jan 2, 1979 |
| Priority date | — |
| Expiry date | Jun 30, 1997 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA01B63/114
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A control system is provided for a hydraulically operated tractor hitch assembly including a rockshaft operated by a main cylinder which is controlled through a spool valve operated by a pilot cylinder which is controlled, in turn, through a solenoid operated pilot valve. The pilot valve is selectively controlled from first and second detector circuits through a gating circuit which is controlled by a third detector circuit which responds to a first error signal developed by comparing a command signal which corresponds to a rockshaft target position and a first feedback signal which corresponds to the actual rockshaft position and which is generated by a potentiometer connected to the rockshaft. The first detector circuit is operative when the first error signal is of relatively high magnitude and responds to a second error signal developed by comparing the first error signal with a feedback signal derived through a signal modifying circuit from the potentiometer connected to the spool valve, with the signal modifying circuit being operative to compensate for a dead zone of the spool valve and with the operation being such that the rockshaft is rotated to a position within a zero t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.