GB434480A - Improvements in or relating to automatically variable power transmission gearing especially for motor vehicles - Google Patents

Abstract

434,480. Variable - speed gearing. HOBBS, H. F., 58, Lillington Road, Leaming- ton Spa. Dec. 29, 1933, No. 36599. [Class 80 (ii)] Relates to automatically - variable gearing suitable for vehicles of a kind comprising eccentric planetary weights carried by a driving member and geared to a driven shaft which is prevented from rotating except in one desired direction. Specification 358,732 describes gearing of this kind, the planetary weights being shown at 12 in Fig. 1 of that specification, and the driven shaft at 14, there being reversible detent rollers 26 between arcs on a fixed member 20 and a one-way drum 40 on the shaft 14. The best or most suitable pressures of the springs of the detent rollers increase with the load, that is with the difference between the speeds of the driven and driving shafts. The spring pressures are unnecessary on direct drive and must be very pronounced on lowest speed. The invention provides means for varying the spring pressures on the detent rollers proportional to the difference in speeds between driven and driving shafts. A pump F, Fig. 1, driven by the driving-shaft is opposed to a pump J driven by the load shaft so that oil pressure in a duct d<4> is proportional to the difference in speeds. In the neutral position of the gearing shown, this oil escapes round a groove d in a piston D and out at a duct d<6>, Fig. 2. The piston rod B<2> of this piston is jointed to a lug A<6>, Fig. 1, of a cage A<5> which carries springs A<4> acting on the detent rollers A<2> which operate between arcs on a fixed member A and a one-way drum A'. For forward driving, a manual wheel B<5> through a lost-motion rack sleeve B<4> depresses the piston D until oil from the duct d<4> enters a port d<1> in the piston flange and escapes by a port d<7>, Fig. 2. While over the piston, this oil exerts the required differential pressure which is communicated to the detent springs A<4>. For reversed driving, the piston D is raised and the differential pressure is exerted underneath it and in a reversed direction on the cage A<5>. In Fig. 3 (not shown), is an arrangement in which the cage A<5> is pulled in opposite directions through springs by the accelerator and by a governor on the load shaft. Specifications 353,750, 434,353, and 435,988 also are referred to.