Motor vehicles – Special driving device – Portable track
Patent
1991-08-12
1993-12-28
Focarino, Margaret A.
Motor vehicles
Special driving device
Portable track
180 926, 180 95, 180 954, 305 22, 305 24, 305 27, B62D 5504
Patent
active
052731260
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to tracklaying vehicles and in particular, but not exclusively, to tracklayer tractors.
Hitherto, the track-engaging ground rolls of such tractors have been carried on rigidly-mounted axles and any changes in track length due to track wear or local deflections between idlers have been minimal and easily accommodated by the usual spring idler units. Such tractors will hereinafter be referred to as "fixed axle" tractors.
Although known tracklayer tractors have improved grip and reduced soil compaction compared with known four-wheel tractors, they share the common disadvantage of all fixed axle vehicles that their top speeds are in practice restricted by the amount of vibration that the vehicle, and its driver, can withstand. This is particularly disadvantageous when speed is of the essence, e.g. when taking the tractor from site to site along a public highway.
This disadvantage may be overcome by fitting the tracklaying vehicle with some form of suspension system. One of the main problems to be overcome with those track suspension systems which operate by allowing relative movements of the track engaging rotating elements, is the need to provide a controlled (preferably constant) track tension for the full range of suspension travel.
For example when a conventional swing link suspension system is deflected, the length of track required to encompass the track engaging rotating elements changes. Since the actual track length cannot be altered a compensating device must be incorporated which can adjust its position so as to maintain track tension and take up track slack. This latter can typically be 4% or so of the actual track length. The usual fixed-axle tractor spring idler units referred to above are quite unable to provide the range of idler movement to take up this level of track slack while still maintaining a constant track tension. Overcoming the problem by increasing the size of the conventional spring units would require the use of such extremely large/heavy springs that the solution would be impractical for most applications.
An object of the present invention is to provide a suspended-track tracklaying vehicle in which the problems discussed above are overcome or at least significantly reduced.
According to the present invention, a suspended-track tracklaying vehicle (e.g. a tracklayer tractor), comprises an endless track, a movable sub-frame supported by track-engaging elements backing the ground-engaging portion of the track, a drive sprocket or the like which remains positionally fixed relative to the vehicle body, and a track-engaging compensator idler mounted for movement, preferably substantially straight line movement, relative to the sub-frame under the action of one or more spring-loaded compression units acting between the compensator idler and the vehicle body.
Conveniently, the line of action of the or each compression unit lies in or close to a diametral plane of the compensator idler and is connected with an axial support for the compensator idler via a slide unit extending in said plane between said axial support and the distal end of the compression unit.
Conveniently, the slide unit is displaceable only in a substantially horizontal direction relative to the sub-frame.
Conveniently, the substantially linear path of the compensator idler lies within an angle range of plus or minus 20.degree. (preferably 0.degree.) to the horizontal.
Conveniently, the suspension system comprises a parallel swing link mechanism adapted to control the movement of a subframe carrying the track-engaging ground rolls and the compensator idler mounting.
Conveniently, the track wraps around a bottom rear idling support with an angle of wrap which is bisected by an associated link of the swing link mechanism.
Conveniently, in this latter case, the adjacent ends of the compression unit and the nearer swing link are secured to the vehicle body in substantially coaxial fashion.
Conveniently, the line of action of the compression unit relative to the adjacent part of the vehicle bod
REFERENCES:
patent: 1368652 (1921-02-01), Pennington et al.
patent: 2051496 (1936-08-01), Sarrazin
patent: 3532397 (1970-10-01), Johnson
patent: 3994352 (1976-11-01), Siorek
patent: 4305476 (1981-12-01), Blass et al.
patent: 4313516 (1982-02-01), Terry
patent: 4681177 (1987-07-01), Zborowski
Knox John
Reed John N.
Boehler A. M.
British Techology Group Ltd.
Focarino Margaret A.
LandOfFree
Tracklaying vehicles does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tracklaying vehicles, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tracklaying vehicles will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1536798