GB281107A - Variable speed hydraulic transmission gear - Google Patents

Abstract

281,107. Brown, A. Hall-, and Jones, E. W. Dec. 22, 1926. Fixed-abutment type: governing and regulating.-A variable-speed transmission gear comprises a cylindrical barrel 5 having pump and motor rotors 1, 3 respectively, of the revolving drum and blade type disposed coaxially therein. The pump and motor casings are defined by revoluble end-plates 11, 12, shaped so that the rotors may slide freely through them and by an intermediate division plate 7 which is non- rotatable but which is adapted to be moved longitudinally in the barrel to vary the relative, capacities of pump and motor and consequently the relative speeds of the driving and driven shafts 19, 20 on which the rotors 1, 3 respectively are splined to slide. A valve 18, Fig. 2, between the motor inlet and exhaust ports 16, 17 respectively is provided by which the supply of liquid from the pump may be deflected from supply to exhaust and vice versa to control the direction of rotation of the motor. When the valve is in the intermediate position shown in Fig. 2 the circulation of fluid is arrested and the motor functions as a brake. The blades of the rotors have trunnions 25 at their outer edges which engage pockets formed in rings 27 revolubly mounted in the barrel 5, so as to reduce friction, while maintaining effective contact of the blades with the barrel. An enclosing outer case 28 of such volume as to house the liquid of the system without permitting it to reach the shafts is provided. A circulation pump 29 driven by the shaft 19 charges and maintains the system, a loaded relief valve being provided in the highest part of the hydraulic system for the removal of air and the prevention of excessive pressures. The inner ends of the drums 1, 3 are connected by flanges to the division plate 7 and this plate is moved, to change the gear, by a lever 6 which may be controlled from a centrifugal or fluid pressure governor. Movement of the plate 7 to the right from the position shown causes a splined sleeve 37 which is always in mesh with the clutch shaft to mesh with the rear shaft 20 through a spline 35 to give a direct drive.