Ratio control valve for tractor rear axles
US4455051A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 15, 1981 |
| Grant date | Jun 19, 1984 |
| Priority date | — |
| Expiry date | Jun 15, 2001 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB60T8/263
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
The invention relates to an improvement in a valve for a tractor air brake system for changing the pressure delivered to air brakes on a tractor rear axle during "bob tail" operation and particularly to a valve wherein the ratio is changed by communication of control pressure to a second control surface in accordance with the presence of trailer emergency pressure. The improved ratio control valve enables fluid pressure communication to both control surfaces of the ratio valve until a predetermined input pressure is reached so that the "crack-open" input pressure for both the "trailer-connected" and the "bob tail" modes of operation will be the same. Further in accordance with the invention, a blend-back valve is provided which is biased by the available fluid pressure in the tractor reservoir tank so that the maximum available tractor reservoir pressure may always be applied to the tractor rear axle brakes even when the trailer is operating in the "bob tail" mode.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.