Abstract: A hydraulic control system for a continuously-variable-ratio-vehicle transmission of the toroidal-race rolling-traction type, in which the mechanism for positioning each roller includes a double-acting ram (11). The two opposed faces of the ram are exposed in normal use to the pressures of two separate lines of fluid (21, 23), each being pressure-controlled by separate valves (32, 34) located downstream of the respective ram face. The outputs of those separate valves combine in a common region (31), and further valve means (40, 41) open to connect that region to each line in response to the occurrence of a predetermined difference in pressure between the region and that line. In such circumstances such connection and the resulting transfer of fluid from the region to the line helps to counteract any tendency to fluid starvation in the line.

Abstract: A variator for a transmission of the toroidal-race rolling-traction type in which a multiplicity of input discs (1-4) and output discs (11-13) are arranged in coaxial sequence, all disc except the first (1) and last (4) in the sequence being formed with races (9, 10) on both of their faces. Drive is transmitted from the output discs to one (35) or several (45-47) output shafts, the output shaft or shafts preferably lying parallel to but displaced from the common axis (8) of the discs. Alternative ways of inter-relating the orientation of the torque-transmitting rollers (20), to produce single or multiple outputs of the transmission, are described. The invention offers the prospect of a variator of higher-than-normal traction-transmitting capacity but using discs of only normal size.

Abstract: A rotatable disc (1, 3) formed with a coaxial part-toroidal race (26, 27) for use as the input or output disc of the variator for a transmission--especially of the full toroidal kind--of the toroidal-race rolling-traction type, in which the torus radius (r.sub.d) of the race, that is to say the radius of curvature of the race measured at a chose point on the race and in a plane including the disc axis, decreases as the distance of that point from the disc axis (5) diminishes. Such decrease of the torus radius may be either continuous or discontinuous.

Abstract: A continuously-variable ratio transmission of the toroidal-race rolling-traction type, especially in and for an automobile vehicle. The ratio transmitted by the rollers (10) is determined by the position of a double-ended piston (15), the ends of which move in cylinders (17, 16) respectively connected to further cylinders (31, 36) the pistons (33, 38) of which are movable by the opposite limbs of a rocking pedal (42) controlled by the operator. Rocking of the pedal in one direction depresses one such piston (e.g. 33) and releases the other, thereby moving the double-ended piston (15) in one direction and so inducing ratio change in one sense, while rocking the pedal in the opposite direction has the opposite effect. The cylinders (31, 36) of the pedal-controlled pistons may be mounted in a fluid reservoir (34), and formed with ports through which the fluid lines are topped-up from the reservoir each time the pistons (33, 38) rise close to the tops of their strokes.

Abstract: A two-regime, continuously-variable-ratio transmission of the toroidal-race rolling-traction type in which the variator (2) reducing epicyclic (10) and mixing epicyclic (15) are all coaxial, in which the driving connection between the variator output and the sun gear (18) of the mixing epicyclic includes a layshaft (23) or the like lying radially outboard of the reducing epicyclic, and avoids the use of a drum-like component which would surround those parts of the variator lying downstream of its output member (8). The invention also facilitates the use of gear units of equal ratio, and indeed of substantially identical structure, for the reversing (10) and mixing (15) epicyclics.

Abstract: A driveline for a wheeled vehicle in which two laterally-displaced driving wheels (37, 38) are driven by the output (33, 36) of a transmission of continuously-variable ratio. The transmission is capable of a "geared neutral" condition, and is driven by way of a slipless connection (5, 6, 7; 70-73) from the engine (2). The engine output axis (3), the engine/transmission connection and the variator output axis (15) are arranged in a "U"-shaped formation. Such an arrangement promotes a compact and well-balanced installation in which the vehicle centerline (1) may roughly bisect the engine, and the wheel half-shafts (43, 44) can be nearly equal in length. Alternative embodiments are described in which the output axis of the variator coincides with the final drive axis (FIG. 3), or is parallel to but displaced from it (FIG. 1).

Abstract: A hydraulic control valve for a continuously-variable-ratio transmission (CVT), particularly one of the toroidal race rolling traction type. The transmission includes hydraulically-operated clutches (25,26) whose capacity to transmit torque varies with the operating pressure supplied to them. The transmitted ratio is related to the position of a hydraulic ram (35), which when it overshoots its normal stroke creates a pressure rise upstream of it in the circuit. This pressure rise first resists further overshoot, and then causes a reduction in the clutch operating pressure. Ram position is controlled by valves (56,57) which are located downstream of the ram, and which are themselves sensitive (via 58) to feedback from upstream circuit pressure: when that pressure rises, the valves open so as to depress the downstream circuit pressure by which the clutches are operated (via 68).