Elevator – industrial lift truck – or stationary lift for vehicle – Stationary lift for roadway vehicle or required component... – Having specific drive means for support
Patent
1981-10-23
1983-07-12
Rolla, Joseph J.
Elevator, industrial lift truck, or stationary lift for vehicle
Stationary lift for roadway vehicle or required component...
Having specific drive means for support
B66B 920
Patent
active
043925545
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a lift mast assembly and more particularly to a lift mast assembly having first and second pairs of spaced apart uprights and upper intermediate and lower guide bearings. The intermediate guide bearings support and guide the second pair of spaced apart uprights for movement between a lowered position and an intermediate position spaced from the lower position and the upper guide bearings support the second pair of spaced apart uprights for movement between the intermediate position and a fully extended position.
BACKGROUND ART
In recent years it has been a goal of lift truck manufacturers to provide a lift mast, of the type used on a fork lift truck, with improved visibility and free lift. U.S. Pat. No. 4,219,302 dated Aug. 26, 1980 to Edward V. Leskovec and U.S. Pat. No. 4,191,276 dated Mar. 4, 1980 to Stanley E. Farmer disclose a lift mast having improved visibility and free lift. Free lift is well known in the art as elevational movement of a lift carriage prior to extension of a movable upright assembly past the upper end of the fixed or stationary upright assembly. Although these two designs both accomplish improved visibility and free lift they both require additional parts which tend to be complex in nature and add to the cost of the lift mast.
It is preferred that high visibility be achieved without any additional structure or parts while maintaining free lift as a feature thereof. In order to achieve this it has been determined that the movable lift mast uprights and particularly the upper end thereof be spaced elevationally beneath the upper end of the fixed uprights so that the movable uprights and particularly the carriage can move to a preselected elevated face lift position, from a fully lowered position, without the upper end of the movable upright passing the upper end of the fixed upright.
Typically, lift masts of this type require upper and lower guide bearing assemblies, such as rollers, to be provided between the fixed and movable uprights so as to guide the uprights smoothly so as to prevent sticking, bending, excessive wear and the like. Also, it has been accepted that the distance between the upper and lower guide bearings should be spaced as far apart as possible to offer the maximum amount of movable upright extension relative to the fixed upright for a given length as possible. However, placement of the movable upright beneath and spaced from the upper end of the fixed upright requires the upper guide roller to be moved downward to a location to support the upper end of the movable upright when in its lowered position or provide an additional guide roller adjacent the upper roller.
This added intermediate guide roller creates an additional series of problems. The total overall maximum height of extension of the movable upright assembly is reduced, separation of the mast sections for disassembly and maintenance are further complicated in that the cutout of the flange at the upper end portion of the fixed upright must be increased in length resulting in weakening of the strength of the fixed upright sections, and alignment of the upper and intermediate guide rollers to provide proper contact between the movable upright and the rollers to reduce premature wear, failure and alleviate the potential of binding of the movable uprights.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of one embodiment of the present invention, a lift mast having a first upright and a second upright mounted on said first upright and elevationally movable relative thereto is provided. Upper, intermediate and lower guide bearings are provided for supporting and guiding the second upright on the fixed upright. The intermediate guide bearing contactably supports and guides the second upright when the second upright is elevationally positioned between a lowered and intermediate location and the upper guide bearing supports and guides the second upright when the second uprigh
REFERENCES:
patent: 3556247 (1971-01-01), Shinoda et al.
patent: 3999267 (1976-12-01), Leskovec et al.
patent: 4034885 (1977-07-01), Stedman
patent: 4124104 (1978-11-01), Yarris
patent: 4191276 (1980-03-01), Farmer et al.
patent: 4219302 (1980-08-01), Leskovec
patent: 4312427 (1982-01-01), Stedman
Hickman Alan J.
Rolla Joseph J.
Stormer R.
Towmotor Corporation
LandOfFree
Lift mast assembly does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lift mast assembly, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lift mast assembly will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-194063