Lift trucks and extensible mast structures therefor
US5330032A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 18, 1993 |
| Grant date | Jul 19, 1994 |
| Priority date | — |
| Expiry date | Feb 18, 2013 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB66F9/08
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
An extensible mast structure having a fixed mast section and at least one movable mast section mounted on the fixed mast section. A load carrying carriage mounted on the movable mast section for vertical movement relative to the movable mast section. A primary jack connected to the movable mast section for moving the load carrying carriage and a secondary jack connected to the fixed mast section for moving the movable mast section to extend the mast structure. The relative operational cross-sectional areas of the primary jack and the secondary jack are selected to sequence movement of the primary jack to move the load carrying carriage before the secondary jack moves the movable mast section. A stop on the fixed mast section to engage a stop on the primary jack at an intermediate point in the stroke of the primary jack which permits the primary jack to assist the secondary jack and move the movable mast section during the remainder of its stroke while continuing to move the load carrying carriage and the secondary jack continues its stroke so that movement of the movable mast section is substantially uninterrupted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.