Patent GB-538401-A (GB)
Title: Improvements in and relating to motor vehicles
IPC: B60P3/42
Filed: 1940-01-04
Abstract: 538,401. Converting motor cars and trucks to tractors. BERNHARD, O. Jan. 4, 1940, No. 244. [Classes 79 (i), 79 (ii), 79 (iii) and 79 (iv)] In means for converting a motor car or truck to a tractor of the kind described in Specification 382,462 and comprising a sub-frame 8, 9, 15 connected by a three-point attachment to the car chassis after the rear wheels have been removed, said subframe supporting the chassis by the usual springs and being mounted on tractor wheels 21, 22 or endless tracks, the drawbar or coupling for an implement is connected at 17 to the sub-frame so that the latter takes all the draft and braking stresses when in use. In the construction shown the sub-frame is universally-connected at 12 to a transverse member 11 of the chassis, this connection 12 being immediately below the cardan joint (not shown) of the propeller shaft enclosed in the usual casing 5 fixed to the axle casing 6. To effect the conversion the rear end of the chassis frame 2 is jacked up and the rear wheels are removed. The sub-frame with its wheels is then manoeuvred into place and connected at 12 to the chassis after which the latter is lowered on to the sub-frame, wedge-shaped guide pieces 45 on the axle casing centring themselves between seats 41, 42 on the sub-frame, which is then secured to the axle casing by clamps 47. The differential shafts or half axles are connected by universal couplings 50 to shafts 32 mounted in the sub-frame and connected by single or double reduction chain gearing to shafts 34 on which the road wheels are mounted. The three chainwheel shafts 32, 33, 34 are mounted in bearings in side plates 19, 20 of the sub-frame, these plates being connected at their forward ends by tubes 27, 28 to the members 8, 9 of the sub-frame. The chain gearing is enclosed in casings 23 .. 26. Change gears. The chain wheels 35, 36 of the rear chains may be readily interchanged to change the gear ratio of the transmission, and for this purpose they are connected by a bar 60 pivoted on a long pin 61. Thus, after the chain wheels have been freed from their shafts they can be moved outwardly with the bar until the latter clears the ends of the shafts, after which the bar can be rotated through 180 degrees to interchange the chain wheels on their shafts, the bar and chain wheels being then slid back to the original position of the bar and the chain wheels being secured again on their new shafts. The chain remains on the chain wheels during this operation. The gear ratio may also be changed by providing different sets of chain wheels. The coupling between a differential shaft and its shaft 32 comprises an adaptor 50 provided with holes 51 fitting over partspherical members 53 on an end flange or hub of the differential shaft. The adaptor is provided with a square socket 55 engaged by a squared member 56 on the shaft 32, this member 56 having curved surfaces as shown, the play provided here and at the members 53 allowing for universal movement. In a modification in which single reduction chain gearing is used the middle shafts 33 are dispensed with and the road wheels 21, 22 are inside the side plates 19, 20 of the subframe, being in line with the front wheels 7. According to the Provisional Specification the second train of reduction gear may consist of a spur pinion meshing with an internally-toothed gear wheel.