Hydraulic lift apparatus for a battery driven lift truck
US5649422A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 26, 1995 |
| Grant date | Jul 22, 1997 |
| Priority date | — |
| Expiry date | Jan 26, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/70
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
A hydraulic lift apparatus for a battery driven lift truck includes a hydraulic lift cylinder. A hydraulic pump operates as a pump in a load raising mode, so as to feed pressure fluid to the lift cylinder. The hydraulic pump operates as a motor in a load lowering mode. The hydraulic pump is driven by the pressure fluid displaced by the lift cylinder. A direct current machine is coupled to the hydraulic pump, so as to operate as an electric motor in the load raising mode and to operate as a generator in the load lowering mode. A useful brake circuit is energized by the direct current machine in the load lowering mode. A valve assembly is disposed in the pressure fluid path between the lift cylinder and the hydraulic pump. Control apparatus are provided for controlling the valve assembly and including speed regulating apparatus for varying the speed of the direct current machine. At least one secondary hydraulic consumer is adapted to be connected to a hydraulic pressure source via an associated control valve. A lowering branch is provided between the valve assembly and a connection is provided between a check valve and the inlet of the hydraulic pump. The secondary hydraulic consume…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.