892,026. Rotary engines and pumps. RHODEN, N. F. June 5, 1959, No. 19226/59. Class 110 (2). [Also in Groups XXIX and XXXI] An hydraulic power transmission system comprises a constant-speed rotary-acting, variable capacity impeller pump adapted to be coupled to a constant speed prime mover, one or more fluid pressure rotary driven units connected to the pump by a delivery and return conduit system, a conduit system interconnecting chambers in the pump and having valves controlling the output of the pump, and valves arranged in a reversing valve conduit system for controlling the direction of rotation of the driven unit or units. The pump consists of a cylinder C, Fig. 1, which is slidably keyed to a shaft A driven by the prime mover and is formed with an impeller C2 extending into chambers G, H and slidably received in a recess in a partition F between the chambers G, H whereby the shaft, cylinder and partition rotate in unison and the cylinder is axially-movable relative to the shaft and partition. Vanes J are positioned at 120 degrees interval in the chamber G and are formed with projections, which may be provided with ball or roller bearings, engaging cam grooves b2 in the partition F and a disc B secured to the shaft so that the vanes are successively moved radially outwards during the the passage of the impeller C2. Attached to each vane is a stop valve E which moves radially with the vane to prevent the passage of fluid past a piston D located in a groove in an extension of the cylinder C, the stop valves being guided in grooves in the piston. The partition F is formed with an annular groove F2 to receive fluid returned from a return conduit f, a port F4, Fig. 19, which connects the recess with the cylinder G on the trailing side of the impeller, and a port F3 which interconnects the chambers G, H on the leading side of the impeller. The output from the pump is fed from chamber H to a conduit h, Fig. 32, leading to a velocity-control valve V having portions Vh, Vg, Vx, Vf controlling the flow of fluid through conduits h, g, x, f, respectively, conduit g being connected to chamber G, conduit x being a by-pass passage, and conduit f being the return conduit. The velocitycontrol valve is connected by conduits to a reversing valve u connected to fluid chambers leading to and from the driven units. Each driven unit consists of a rotor N, Figs. 22 and 23, having slots which are disposed at 120 degree intervals and receive vanes P having projections p3, which may be provided with ball or roller bearings engaged in cam grooves q, q2 in the end walls of a stationary cylinder Q. A vane R is secured to the cylinder and as the rotor N is rotated by fluid pressure from one or other of conduits S leading from the pump, depending on the position of the valve u, acting on the vanes P, the vanes are successively retracted radially inwards as they pass the stationary vane R. The rotor N has a spindle N3 which is threaded to receive a wheel T, such as the road wheel of a vehicle, formed with a sleeve supported by a roller bearing U on an extension Q5 of the end wall of the cylinder Q. The velocity control valve is movable into five positions. In position 1, the driven units are immobile, the valve Vf being closed and the chambers G, H connected together and to the return conduit f leading to the annular groove F2 in the partition F. The effects of suction and pressure in the chambers G, H moves the cylinder C and piston D to the left to a position of minimum co-operation between the impeller C2 and vanes J. When the valve is moved to its second position, valve Vf is opened and valve Vx closed resulting in the minimum output of the pump being transmitted to the driven units to drive the vehicle at minimum velocity. When the minimum velocity is reached the valve is moved to position 3 in which valves Vh and Vx are closed. The pressure in chamber H moves the cylinder C and piston D to the right to increase the output of the pump and accelerate the vehicle fluid being discharged from chamber G to the driven units. At the desired velocity, the valve is moved to its fourth position wherein valve Vh is opened and valve Vg closed, valve Vx also remaining closed. The closing of chamber G prevents any change occurring in the output of the pump. In position 5, all valves Vh, Vg, Vx and Vf are open and the driven units are independent of the pump, thus permitting the vehicle to be towed. A relief valve interconnects conduits h/g and f between the valves V, u to relieve excess pressure where the valve Vf is closed to effect deceleration of the vehicle. Closing valve Vf causes suction in pipe h/g to move a piston against a spring opening ports w, y so that conduit f is connected to conduit h/g. The driven units may have different vane areas so that the torque is divided proportionally to the units. A port Z2 in the conduit f between the valves V, v is connected to a pipe connected by a ball or diaphragm valve to atmosphere to permit the escape of air from the system.