GB605814A - Improvements relating to agricultural tractors and the like - Google Patents

Abstract

605,814. Endless track vehicles. NUFFIELD MECHANIZATIONS, Ltd., MERRITT, H. E., and CULPIN, C. Jan. 5, 1946, No. 466. [Classes 79 (i) and 79 (iv)] A half-track attachment for agricultural tractors and the like, comprises a track-driving sprocket mounted on the tractor-driving axle and out of engagement with the ground-engaging portion of the track, and a pair of bogie wheels which are supported by a beam pivotally mounted to the tractor on an axis spaced apart from and parallel to the driving axle and located in or substantially in a plane bisecting the angle contained by the endless track lying on the ground and that extending between the sprocket and rear bogie wheel. As shown in Figs. 2 and 3, each half-track attachment comprises a driving sprocket 10, a pair of bogie wheels 7, 8 and an endless track 9 which according to the Provisional Specification may be of the girder type. The sprocket is secured to the tractor half-shaft by bolts 24 and is adapted to be axially slidable thereon for adjusting the vehicle track. The sprocket centre lies on the apex of a triangle, the lower angles of which position the centres of the bogie wheels 7, 8. The latter are journalled on to a box-section beam 6, to the centre of which is secured a yoke 12 which is pivotally connected by a pin 13 to a bracket 14, said bracket being in turn bolted to the flanges 16 of the tractoraxle casing 17, and has lateral adjustment in conformity with the sprocket wheel adjustment for varying the vehicle track. The bracket 14 is provided with rubber buffers 22 which may engage stops 21 located on the beam 6. The position of the pin 13 is such that its centre lies in a plane 19 which bisects the angle contained by the endless track lying on the ground and that extending between the sprocket and the rear bogie wheel 8. The line of action of the resultant thrust passes through the pivot axis 13 and consequently the pressure distribution between the endless track 9 and the ground is unaffected by the magnitude of the pull in the track. Also the tractive effort does not tend to tilt the half-track attachments. An idler wheel 20 is journalled in a bracket 20A is fixed to the beam 6. Means are provided for tensioning the endless track by adjustment to the front wheel bogie. This is effected by rocking the bogie wheel 7 about a pin 40 journalled in the beam 6 which is offset from the wheel axle 25. The wheel is locked in position by means of a bolt passing through aligned holes in brackets 26, 30. In a modification, Fig. 5, the beam 6 carries a pair of cranked brackets 31, pivoted thereto by pins 32. The brackets comprise a pair of arms 33, 34 to the ends of which are respectively journalled the bogies 7, 8 and idler wheels 35, the pivot pin 13 lying in the plane which bisects the angle contained by the endless track lying on the ground and that portion extending between the sprocket and rear bogie wheel.