Patent · US Expired

Four wheel drive vehicle

US4747462A · kind A · utility

7Cited by

5References

4Claims

0Family size

Assignee

Deere & Company · US

Inventors

Hans H. Herrmann · Seattle, US
Klaus Hauk · Altrip, DE
Michael Teich · Mannheim, DE

Key dates

Filing date	Aug 27, 1986
Grant date	May 31, 1988
Priority date	—
Expiry date	Aug 27, 2006

Classification

Technology area (CPC B)Performing Operations; Transporting
CPC primaryB60K23/0808
WIPO fieldTransport
WIPO sectorMechanical engineering

Abstract

A mechanical four wheel drive tractor having a solenoid valve which is de-energized to effect engagement of drive to the front wheels in a predetermined operational mode. Normally, the valve is controlled by an operator switch but when the engine is overloaded and exhaust gas temperature rises, a thermal sensor breaks the circuit to the solenoid valve so that four wheel drive is automatically engaged. This action is restricted to a low gear range by a switch linked to the mechanism selecting between the low range and a high range. Restriction to a low gear range prevents unwanted automatic four wheel drive engagement from occuring in other gear ranges without regard to vehicle speed. Automatic engagement of four wheel drive reduces the overload on the transmission.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.