Fire escape – ladder – or scaffold – Ladder with land vehicle
Reexamination Certificate
2000-02-11
2001-04-03
Chin-Shue, Alvin (Department: 3634)
Fire escape, ladder, or scaffold
Ladder with land vehicle
C182S097000, C280S166000
Reexamination Certificate
active
06209682
ABSTRACT:
DESCRIPTION
1. Technical Field
This invention relates generally to a ladder assembly for providing access to, and egress from, an operator station of a large track-type tractor, and more particularly to such a ladder assembly that provides access and egress to the operator station from a forward side of the tractor.
2. Background Art
Typically, an operator, or other worker, climbing into, or out of, an operator station of large track-type tractors, such as elevated sprocket earthmoving equipment, uses a series of steps and grab handles. Typically, the steps and grab handles are parts of, or located on, the push arm, tilt cylinder, radiator guard, track, hood and engine enclosures, fenders, and cab. Often these steps and grab handles are not conveniently located. When added as ancillary components, they require separate operations to attach to the tractor during the assembly process. Additionally, the variously-located steps and grab handles are prone to damage during operation of the equipment.
Several structures have been proposed to overcome the problems associated with separately located steps and grab handles positioned at various locations on large equipment. For example, U.S. Pat. No. 4,243,120 issued Jan. 6, 1981 to Pratt, Jr., et al. for a RETRACTABLE BOARDING LADDER, and later granted U.S. Pat. No. 5,339,919 issued Aug. 23, 1994 to James W. Boyd, describe ladder arrangements which require counter weights, guide tracks, cables, and rollers to raise and lower the ladder. The counter weighted structures require constant maintenance and a large number of components. U.S. Pat. No. 4,131,293 issued Dec. 26, 1978 to John J. Kindle describes a ladder structure that is assisted by springs coupled with a complex linkage positioned at the rear of a farm implement. This structure also requires constant maintenance to assure operation of pivot points in the complex linkage.
U.S. Pat. Nos. 3,869,022 issued Mar. 4, 1975 to Harold J. Wallk, for a TELESCOPING STEP LADDER, and 5,033,582 issued Jul. 23, 1991 to Lawrence J. Hoben and entitled RETRACTABLE LADDER ASSEMBLY, are assigned to the assignee of the present invention. Both of the patents, along with U.S. Pat. No. 5,064,022 issued Nov. 12, 1991 to George W. Graham for LADDER APPARATUS AND METHOD FOR LARGE MOBILE EQUIPMENT, describe different telescoping arrangements whereby the ladder is moved between lowered and raised positions. Telescoping ladder arrangements, in general, require closely toleranced mating components.
The present invention is directed to overcoming the problems set forth above. It is desirable to have a ladder device which provides access to an operator station on a large track-type tractor that does not require complex linkage, cables, and other components that require extensive maintenance. It is also desirable to have such a ladder arrangement which does not require closely toleranced mating components. Furthermore, it is desirable to have such a ladder that, when in the carry position, is stored within a protective enclosure to avoid damage to the ladder during operation of the vehicle in a construction environment.
DISCLOSURE OF THE INVENTION
In accordance with one aspect of the present invention, a ladder assembly for providing access to, and egress from, an operator station of a track-type tractor includes a ladder support structure and a ladder pivotally attached to the ladder support structure. The ladder support structure has an elongated box portion having first and second ends, with the first end being an open end. The ladder support structure is pivotally attached to a side panel of a radiator guard of the track-type tractor. The ladder has a plurality of steps disposed between first and second ends. The ladder is movable between a first position at which the ladder is disposed within the elongated box portion of the ladder support structure and a second position at which the first end of the ladder is pivotally connected to the first end of the ladder support structure and the second end of the ladder is disposed at a position readily accessible from a ground surface on which the tractor is supported.
Other features of the ladder assembly embodying the present invention include the ladder support structure being selectively movable between a first position at which the elongated box portion of the ladder support structure is disposed in a substantially horizontal position, and a second position at which the elongated box portion is substantially vertically disposed at a position adjacent the side panel of the radiator guard of the track-type tractor.
Additional features of the ladder assembly embodying the present invention include the ladder assembly having a means for maintaining the ladder support structure at the first position whereat the elongated box portion of the ladder support structure is disposed in a substantially horizontal position. Still other features include the ladder, when disposed at the second, or extended position, being in a vertically inclined position and extending over a tilt cylinder and a push arm of the tractor.
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Duffy Joseph F.
Martin Lionel A.
Swanson Steven C.
Caterpillar Inc.
Chin-Shue Alvin
Glastetter Calvin E.
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