Motor vehicles – Special driving device – Portable track
Reexamination Certificate
1999-09-09
2001-01-23
Hurley, Kevin (Department: 3619)
Motor vehicles
Special driving device
Portable track
C180S009400, C180S906000
Reexamination Certificate
active
06176334
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a tracked vehicle. It relates particularly to a tracked work vehicle having a plurality of endless track drives, at least a portion of them both driveable and steerable.
BACKGROUND OF THE INVENTION
It has long been known to provide work vehicles with endless track assemblies, or tracks (sometimes referred to as “crawler treads”), for ground support in order to provide increased traction and support, or flotation, upon moist or loosely packed soils. Due in part to their larger footprints which compact agricultural field soils less than do the tires of wheels of typical agricultural tractors, tracked vehicles have in recent years become increasingly popular in crop farming as well, particularly in connection with larger, heavier and more powerful tractors. Track assemblies, including undercarriage such as idler and bogie wheels, pivot brackets and other supporting structure may be referred to as track suspensions.
Maneuverability of a tractor with a connected implement is of importance, especially at the headlands of a field (i.e., at the ends of crop rows) where a tractor with implement must be turned 180 degrees. Larger wheeled tractors, which are provided with rigid frames having larger turning radii if provided with conventional front wheel steering systems, can require excessive maneuvering and/or width of headland. Their frames are therefore often hinged, or articulated, and they are steered by changing the angle of a front frame with respect to a rear frame, typically by use of a hydraulic cylinder bracketing a pivot joining the front and rear frames. This is an expensive configuration of construction, however, and is generally used only on very large tractors.
Larger tracked tractors utilizing articulated frames are produced in the QUADTRAC™ series of models by Case Corporation, assignee of the present invention. These utilize four endless track assemblies, one each generally located near the front and rear ends of the right and left sides of the tractor. Other tracked tractors generally utilize rigid frames with one endless track on the left side and another on the right side, and are steered by changing speed of either endless track with respect to the other. Such tractors can turn in extremely tight circles, but, in the hands of an inexperienced or inattentive operator, can easily and quickly be inadvertently jackknifed with an implement and damage the implement. Moreover, they provide a harsh ride and generally lack the directional stability desired for ease in making or following long, straight and parallel crop rows.
Because various types of crops often require differing row spacings for efficient utilization of a field, tractors are preferably provided with adjustable track width; i.e., the widths in front and rear elevation views between centerlines of tires or endless track assemblies. While this is relatively easily accomplished with wheeled tractors, it is generally a time-consuming and costly operation with a tracked tractor, requiring significant undercarriage disassembly.
It would be advantageous to provide for a work vehicle, such as an agricultural tractor, to offer the better ride and directional stability of a wheeled tractor while also offering the better traction and lesser soil compaction of a tracked tractor, without incurring the expense of an articulated configuration.
It would also be advantageous to provide for such a work vehicle to include endless track drives which are compact and which are relatively easily repositioned to change vehicle track width.
SUMMARY OF THE PRESENT INVENTION
The present invention relates to a track suspension for a tracked vehicle, the vehicle having a longitudinal axis, the suspension including a track, a rotatable drive wheel engaged with the endless track and configured for driving the endless track, a nonrotatable wheel support configured for supporting the drive wheel in rotation; a rotatable drive wheel shaft having a length, rotationally engaged with the drive wheel, and configured for driving the drive wheel in rotation; and a nonrotatable drive wheel shaft support configured for supporting the drive wheel shaft in rotation and configured to be steerable with respect to the vehicle, wherein the wheel support is adjustably securable to the drive wheel shaft support in a plurality of laterally disposed positions and the drive wheel is slidingly positionable with respect to the length of the drive wheel shaft in correspondence with the adjusted position of the wheel support, the laterally disposed position of the endless track suspension thereby being adjustable with respect to the longitudinal axis.
In accordance with another embodiment, the present invention relates to a dual endless track suspension for a tracked vehicle having a left side and a right side, the suspension including a first endless track suspension extending from the left side, and a second endless track suspension, positioned in spaced-apart and opposing relationship to the first endless track suspension, and extending from the right side, the first and second endless track suspensions each including a track, a rotatable drive wheel engaged with the endless track and configured for driving the endless track assembly, a nonrotatable wheel support configured for supporting the drive wheel in rotation; a rotatable drive wheel shaft having a length, rotationally engaged with the drive wheel, and configured for driving the drive wheel in rotation; a nonrotatable drive wheel shaft support configured for supporting the drive wheel shaft in rotation; at least one endless track support undercarriage coupled to the wheel support; a final drive including a planetary gear set having a sun gear slidingly positionable with respect to the length of the drive wheel shaft while remaining rotationally engaged with the drive wheel shaft, an internal ring gear secured to the drive wheel and positioned coaxial and coplanar with the sun gear, and at least one planet gear positioned intermediate the sun gear and the ring gear, the planet gear rotatably supported by the wheel support; and a flexible coupling for flexibly coupling the drive wheel shaft to a power source, the major axis of the drive wheel shaft and the drive wheel shaft support being adjustably pivotable about a substantially vertical axis for steering the vehicle.
In accordance with another embodiment, the present invention relates to a tracked vehicle including a frame having a longitudinal axis, at least one endless track suspension, the endless track suspension including a track, a rotatable drive wheel engaged with the endless track and configured for driving the endless track assembly, a nonrotatable wheel support configured for supporting the drive wheel; a rotatable drive wheel shaft having a length, rotationally engaged with the drive wheel, and configured for driving the drive wheel in rotation; and a nonrotatable drive wheel shaft support configured for supporting the drive wheel shaft in rotation and steerably coupled to the frame, wherein the wheel support is adjustably securable to the drive wheel shaft support in a plurality of laterally disposed positions and the drive wheel is slidingly positionable with respect to the length of the drive wheel shaft in correspondence with the adjusted position of the wheel support, the laterally disposed position of the endless track suspension with respect to the longitudinal axis being thereby adjustable.
In accordance with another embodiment, the present invention relates to a method of adjusting the track width of a tracked vehicle, the method including the steps of (a) unfixing a wheel support of a track suspension from a drive wheel shaft support of the vehicle, (b) adjusting the lateral location of the endless track suspension from a first position to a second position with respect to the drive wheel shaft support, and (c) affixing the wheel support of the endless track suspension to the drive wheel shaft support.
REFERENCES:
patent: 1710116 (1929-04-01), Sembera
patent: 2535
Case Corporation
Foley & Lardner
Hurley Kevin
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