Material handling vehicle having improved chain monitoring
US4499971A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 22, 1983 |
| Grant date | Feb 19, 1985 |
| Priority date | — |
| Expiry date | Apr 22, 2003 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB66F9/08
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
An improved system for monitoring lift chains included within mast assemblies in material handling vehicles disables downward movement of the forks upon detection of a first level of slackness in a lift chain. Since upward movement of the forks is not disabled, the forks may be raised to clear any obstruction causing the chain slackness. A lift chain may also be monitored to detect a broken chain in which case all vertical movement of the forks is disabled. In a material handling vehicle wherein the operator is elevated along a first mast and the forks are elevated along a second mast connected to an operator's platform, dual lift chains in the first mast are individually monitored for both slackness and breakage while dual lift chains in the second mast are monitored in common primarily to detect slackness. Lateral and rotational movement of the forks is also disabled for detection of a slack or broken first mast lift chain, but not for detection of a slack or broken second mast lift chain.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.