Hydro-pneumatic actuator with automatic slack adjuster
US4467605A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 27, 1982 |
| Grant date | Aug 28, 1984 |
| Priority date | — |
| Expiry date | Sep 27, 2002 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16D65/74
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
A two-stage, hydro-pneumatic actuator suitable for use as a railway vehicle brake. The hydraulic cylinder comprises a large diameter bore in which a low- and a high-pressure piston operate jointly during a first stage of operation to effect a high volumetric displacement of hydraulic fluid via a small diameter bore in order to take up the clearance between the brake shoes and wheel. As the brake shoes contact the wheel, the high-pressure piston enters the small bore to interrupt further displacement of hydraulic fluid from the large bore. The force of the high-pressure piston alone during this second stage of operation produces the required brake forces with a high multiplication factor. Make-up fluid is drawn into a chamber on the backside of the low-pressure piston during a brake application stroke an amount corresponding to the over-travel of the high-pressure piston and is subsequently discharged into the hydraulic cylinder during retraction of the brakes to compensate for brake shoe wear. Following brake shoe replacement, a pressure relief valve back dumps excess hydraulic fluid from the large diameter bore to the reservoir when the brake shoes engage the wheels prior to the h…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.