Importance

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Abstract

A lift truck includes an upright assembly having first, second and third telescoping mast sections. Each mast section is formed from pairs of laterally spaced and interconnected I-beam rails. A carriage assembly is mounted for movement along a path on the third mast section. Rollers are provided for mounting the mast sections and carriage assembly together for relative movement. A drive assembly connected to the upright assembly and carriage assembly serves to move the carriage assembly at a first, relatively slow speed over a first portion of the movement path and at a second relatively fast speed over a second portion of the movement path. More particularly, the drive assembly includes twinned actuating cylinders for operatively connecting the first and second mast sections. A first dead chain operatively connects the first and third mast sections. A second dead chain operatively connects the second mast section and the carriage assembly. A guide rod is connected to one end of the second dead chain and a guide sleeve is mounted to the second mast section. The guide rod is received in free sliding engagement in the guide sleeve so as to prevent relative movement between the carriage assembly and the third mast section at all times when the carriage assembly is in a negative lift configuration, that is, below ground level. A stop is mounted to the distal end of the guide rod. When the carriage assembly is in a positive lift configuration, that is, above ground level, the stop abuts against and engages the guide sleeve. This engagement causes relative movement of the carriage assembly along the third mast section when in any positive lift configuration.

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First Claim