Hoist system counterbalance valve signal shutoff
US12115897B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 19, 2021 |
| Grant date | Oct 15, 2024 |
| Priority date | — |
| Expiry date | Jun 28, 2043 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF15B2211/8613
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A hoist valve assembly for a work machine cylinder includes a main control valve, a counterbalance valve and a counterbalance shutoff valve. A main control valve raise position connects a head end of the cylinder with a pressurized fluid source and a rod end of the cylinder to a low pressure reservoir to extend the cylinder. The counterbalance valve is between the rod end and the main control valve, is biased to a closed position and has an open position connecting the rod end to the low pressure reservoir. Rod end and head end pressure signals apply force to the counterbalance valve toward the open position. The counterbalance shutoff valve is positioned between the head end and the counterbalance valve, and has a normal position to apply the head end pressure signal to the counterbalance valve and a shutoff position that blocks the head end pressure signal from the counterbalance valve.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.