The present invention relates to a mounting system for an endless drive track used in a crawler type vehicle, such as a loader, tractor or the like. The mounting system comprises an undercarriage that includes pivotally moveable track rollers that support the track under tension in one position and loosen the track in another position so that the track can be taken off the support rollers and re-installed, and then, when desired, the rollers are pivoted back to a position to maintain a desired tension in the track.
In the prior art, the use of track drives for various vehicles including tractors and self propelled loaders has been expanding. Track laying vehicles have been well known for years, and generally do include guide rollers or sprockets that will guide the track in a path of movement as it is driven. Tension in the track is provided by various adjustment devices including springs, threaded adjusters, pressure actuators and the like.
Rubber or elastomeric tracks require tension to prevent the track from derailing from the drive sprockets, guide rollers, and idlers or bogie wheels. Typical track tensioning mechanisms use screws or grease filled cylinders acting against heavy springs to move the front or rear idler rollers longitudinally to provide the track tension. The longitudinal movement is nearly parallel to the fore and aft direction of vehicle movement. A moveable idler is generally mounted in a telescoping support structure, and the springs maintain the tension when the track stretches. The springs also compress a limited amount when objects get between the track and the support wheels or undercarriage, or when there is some other large, sudden load on the track. Due to the large wrap angle of the track that spans over the adjustable front or rear idlers in prior art systems, large tensioning forces are required. The magnitude of prior tension forces approaches twice the desired track tension force. Hydraulic cylinders have been used to tension tracks but the needed high tensioning forces require large cylinder bores or high hydraulic pressure, and when space is restricted, as in the support frames for a track undercarriage, this becomes a problem.