Material or article handling – Vertically swinging load support – Shovel or fork type
Reexamination Certificate
2002-09-24
2004-03-23
Underwood, Donald W. (Department: 3652)
Material or article handling
Vertically swinging load support
Shovel or fork type
C180S019100
Reexamination Certificate
active
06709223
ABSTRACT:
TECHNICAL FIELD
This invention relates to a compact utility loader which has a traction system and is guided by an operator who walks behind the loader. More particularly, this invention relates to a tracked traction system particularly adapted for use in outdoor, relatively hostile, debris laden environments.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,423,654 to Rohrbaugh discloses a tracked, walk-behind loader for use in the coal mining industry. The loader includes a rotary turntable which mounts an extensible boom. An attachment, such as a bucket, is pivotally mounted on the front of the boom. The boom can be swung about a vertical axis by virtue of the turntable. In addition, the boom can be pivoted about a horizontal axis to vary its angle of inclination relative to the ground, the boom can be telescoped and retracted to vary the boom's length, and the attachment on the front of the boom can be tilted relative to the boom.
The use of a tracked traction system on the Rohrbaugh loader provides good traction in hostile environments, such as those found in the coal mining industry or in ground grooming or working applications. However, in such environments, the Applicants have found that rocks, pieces of dirt, and miscellaneous other pieces of debris often get caught between the tracks and the rotatable track support members. For example, when operating a tracked loader in an outdoor environment in which dirt is being moved, such as when an area of ground is being graded, this debris often gets wedged between the front track support member and the track.
When debris gets wedged between the track and the track support members, various damage and/or operational difficulties often occur. For example, the debris can cause the track to jam which, in turn, can cause the track or other components of the traction system to break. In addition, the track can also become detracked, namely to be pushed off one or both of the track support members, thereby disabling the traction system and the loader. As a result, the traction system must be repaired if damage has occurred or, at a minimum, time and effort must be expended to properly re-install the track if the track has become detracked.
Obviously, these disadvantages detract from the use of a tracked loader in outdoor environments that contain various pieces of debris. There is a need in the art for a tracked loader which is more reliable and which has some ability for clearing itself of debris that would otherwise get wedged or caught between the tracks and the track support members.
Another problem with the Rohrbaugh loader is the use of an extensible and retractable boom to mount the ground engaging attachment. This boom is so large and is so positioned on the loader that it substantially obstructs the view of the operator if the operator is attempting to work the ground immediately in advance of the loader. The operator simply cannot see what he is doing with the attachment when using the Rohrbaugh loader. Moreover, using a rotatable turntable to mount the boom further complicates the structure and provides a loader which, while versatile, has more components and drive systems that are susceptible to breaking down. Thus, there is also a need in the art for a tracked, walk-behind loader that provides the operator with good sight lines to the attachment secured to the loader and which is as simple and durable as possible.
SUMMARY OF THE INVENTION
One aspect of this invention relates to an outdoor maintenance equipment unit which comprises a frame. A ground grooming or ground working attachment is carried on the frame. A source of power is carried on the frame. A traction system is carried on the frame for propelling the frame in forward and reverse directions, the traction system being powered by the power source. The traction system comprises left and right endless drive tracks carried on the frame. Each drive track is entrained around rotatable front and rear support members. The front support member of each drive track is yieldably carried on the frame to be able to move towards the rear support member during operation of the traction system.
Another aspect of this invention relates to an outdoor maintenance equipment unit which comprises a frame having a front and a rear and a pair of laterally spaced uprights at the rear of the frame. A source of power is carried on the frame. A traction system is carried on the frame for propelling the frame in forward and reverse directions. The traction system is powered by the power source. Left and right loader arms are pivotally connected to the upper ends of the uprights. The loader arms slope downwardly from the uprights to terminate in front ends that extend over the front of the frame. A ground grooming or working attachment is pivotally connected to the front ends of the loader arms. At least one actuator extends between the loader arms and the frame for pivoting the loader arms upwardly and downwardly relative to the frame about the pivotal connection of the loader arms to the frame. At least one actuator extends between the loader arms and the attachment for pivoting the attachment relative to the loader arms. A control system is positioned at the rear of the frame and comprises a control handle configured to be gripped and manipulated by a standing operator walking behind the frame.
REFERENCES:
patent: 2284821 (1942-06-01), Heaslet
patent: 2717813 (1955-09-01), Gardner
patent: 3409335 (1968-11-01), Piepho et al.
patent: D359497 (1995-06-01), Rayner
patent: 5423654 (1995-06-01), Rohrbaugh
patent: 112080 (1944-10-01), None
Maximan brochure, 1 pg. (undated).
Maximan Track Loader System brochure, 6 pgs. (undated).
Maximan Track Loader System Price List, Mar. 01, 2000.
South Florida Truck and Equipment Auction web page, referring to '99 Maximan walk behind skid loader w/attachments.
Keagle Ronald T.
Stalpes Philip G.
Walto Joseph J.
Miller James W.
The Toro Company
Underwood Donald W.
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