GB1086008A - Track tensioning device for track driven vehicles - Google Patents

Abstract

1,086,008. Endless-track tensioning devices. BOFORS A.B. Dec. 16, 1964 [Dec. 16, 1963], No. 51307/64. Heading B7H. [Also in Division F2] Each track of an endless-track tractor is entrained around a front idler wheel (not shown) on a shaft journalled in bearings 44 carried by a wheel fork 31 which is slidable in opposed U-section arms 33 on a track frame beam 24 and is loaded to tension the track by a resilient tensioning device 32. The wheel fork 31 terminates in a tubular portion 47 (Fig. 4) containing a cylinder 46 which is filled with grease or other hydraulic medium and houses a piston 48 bearing on a reaction member 49 loaded by a buffer spring 50 which bears through a spring seat 55 against an abutment 51 on the track frame beam 24. Disc springs 62 interposed between the spring seal 55 and an adjustable abutment 60 on a rod 58 connected to the reaction member 49 contain the spring 50 under precompression slightly greater than that normally required to provide track tension. Charging and pressure relief valves 64, 65 for the cylinder 46 are provided with a common locking member (Figs. 5, 6, 7, not shown) arranged to avoid accidents caused by inadvertent release of the valves. Energy absorbing check devices 88 mounted on the arms 33 of the track frame beam to prevent forcible expulsion of the wheel fork 31 by the spring 50 in the event of track rupture each comprise a square, triangular or star section plunger (81, Fig. 10, not shown) which is depressed by the wheel fork 31 upon over-extension to discharge lead from a replaceable slug (84) through lateral openings (86) formed with chip-breaking edges (87). The bearings 44 for the idler wheel shaft are offset from the horizontal centre line of the wheel fork 31 so that the height of the idler wheel can be varied by inverting the fork 31.