GB1141719A - An improvement in or relating to signalling units for draft controlled tractor powerlift mechanisms - Google Patents

Abstract

1,141,719. Tractor power lift mechanism. DAVID BROWN TRACTORS Ltd. 4 Oct., 1967 [8 Oct., 1966], No. 45075/66. Heading A1P. A tractor power lift draft signalling unit (Figs. 1, 2) comprising a housing 10, belleville, or as shown, helical springs 28, 39, inner sleeve 21 with annular plates 34, 35 fixed to it by pins 37, has a plunger 11 which is supported by its end pieces 15, 18 and whose movement in either direction is resisted by the springs. A handle 23 is fixed to the partially rotating inner sleeve 21, and can be located in either of two positions by sprung ball 41 (housed in non-rotatable plate 26) engaging slot 43 or slot 42 of the inner sleeve so that the signalling unit can assume either a high or low sensitivity. This is effected by annular plates 26 and 27, close fitting on plunger 11, having toothed portions that in the position defined by ball 41 engaging slot 43 align the spaces of the toothed portions of plates 34, 35 so that movement of the plunger is opposed by spring 28 only, and in the alternative position abut against the toothed portions of plates 34, 35 so that the plunger movement is opposed by both springs 28 and 39. The second embodiment, Fig. 3, displays the same feature using as resilient means two sets of Belleville washers 71, 72. The toothed portions 61 on the plunger 51 are splines, recessed at 62 to allow partial rotation of plate 63, the inner tooth portions of which either align or non-align the splines depending on the sensitivity required.