Loaded hydraulically actuatable piston and controls system therefor
US4588057A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 25, 1983 |
| Grant date | May 13, 1986 |
| Priority date | — |
| Expiry date | Apr 25, 2003 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T74/19637
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
The horizontally rotatable upper section of a mobile crane is swingable in opposite directions by a speed reducer which is driven by a selectively operable reversible variable speed hydraulic motor. A fail-safe spring-loaded hydraulic brake located on the speed reducer operates, when needed, to slow or stop or prevent rotation of the upper section. A hydraulic control system which supplies pressurized hydraulic fluid to operate the motor and the brake includes a pedal-operated master brake cylinder for selectively applying the brake when the motor is in operation. The brake comprises a cylinder housing, an outer brake piston axially movable through a hole in the housing, and an inner brake piston axially movable in a bore in the outer brake piston. Each piston has an extended position and a retracted position. These pistons are movable alternately to extended (brake-apply) position to force a movable brake plate into frictional engagement with a brake disc which is mounted on and rotatable with a motor-driven input shaft of the speed reducer. A main biasing spring is provided to bias the outer brake piston into extended brake-apply position before the hydraulic motor is turned on a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.