Abstract: A drive mechanism for an infinitely-variable-transmission in which a relatively flexible member 32 connects one or other of the discs 14 to the shaft 10, thereby to accommodate a degree of shaft flexing without distortion of the toroidal cavity.

Abstract: A roller control unit for a CVT includes a cylinder (54) having a piston (70) positioned therein and operably connected to a roller assembly of said CVT thereby to control its position. The unit includes a lubrication supply which comprises a chamber (94) between the cylinder (54) and piston (70) and one or more radially extending passageways (102) through said piston (70). These passageways are in flow communication with the roller and act to direct cooling fluid to said roller. Radial supply of said lubrication facilitates a reduction in flow losses within the supply.

Abstract: A roller control unit (2) for a continuously-variable-ratio transmission includes a cylinder (6) having a cylinder wall and an end wall; and a piston (8), within the cylinder (6) and to which the roller assembly (4) is connected for movement therewith, said unit includes an axially extending shroud (10) of variable length extending between the piston (8) and the end wall, thereby to define in combination with the piston (8) and cylinder (6) a chamber (16) for receiving hydraulic fluid, and in which the shroud (10) comprises a telescopic shroud which in a first position of the piston (8) is extended and in a second position of the piston (8) is retracted.

Abstract: A roller control system for a continuously-variable-ratio transmission (CVT) of the toroidal-race rolling-traction type. The system includes an operating mechanism having a first part (5, 6) operable to control the position of the roller center along the torus center circle but incapable of defining the tilt angle (36) adopted by the roller (7), and a second part comprising a mechanical link (13) connected to the roller bearings and operable to control the tilt angle (36). The link (13) lies substantially parallel to the plane of the roller (7) and is constrained to pass through a predetermined single point (14).

Abstract: A variator assembly comprises a variator of the toroidal-race rolling-traction type using double-acting pistons to control the rollers and differential end load pressure to load the variator, and control means operative to vary the differential end load pressure in sympathy with changes in the net pressure exerted by the roller-control pistons so as to maintain the traction coefficient at the roller disc interface consistently below the limit at which traction would be lost.

Abstract: A roller assembly (10) for use in a toroidal-race rolling-traction variator or like device includes a roller mounted in a carriage (19) which is provided with passageways (33) so that cooling oil from the variator lubrication circuit can be sprayed on to the roller rim via apertures in the carriage and/or in two specially-located spray-bars 38,39 extending from the carriage.

Abstract: A hydraulic control system (70) for a multi-regime CVT (8) includes regime-change clutches (37, 38) which are controlled independently of the variator (10) so that a smooth change of regime may be effected.

Abstract: A variator for a continuously-variable-ratio transmission (CVT) of the half-toroidal traction roller type in which a ratio change results when a roller exercises a first freedom of movement by rotating about a first or precession axis. In addition, the roller mounting has a further freedom of movement about a second or tilt axis. The precession axis is inclined at an angle ("the castor angle") to a plane lying normal to the axis of the races and each equilibrium value of the ratio angle correlates with a unique angular orientation of the roller about the tilt axis.

Abstract: A method of controlling a vehicle driveline including an engine, a continuously variable ratio transmission (CVT) and a final drive in which over a working range of engine speed, the engine is constrained to work to a performance map correlating each value of engine speed to a particular value of engine torque wherein a demand by a driver for a increase in vehicle speed initiates a quick increase in engine speed to a predetermined engage speed without any substantial rise in the final drive speed and then increasing both engine speed and drive speed by a predetermined function until a selected engine speed limit is reached which is commensurate with the driver's demand, and finally maintaining the selected engine speed limit despite further changes in the final drive speed whereby the ratio range of the CVT is extended by providing two regimes of operation with a synchronous ratio between those regimes and the predetermined function is graphically represented as a straight line slope which corresponds to the

Abstract: A continuously-variable-ratio transmission ("CVT") of the band-and-sheave type capable of "torque control", so that what the operator demands, by movement of the accelerator pedal or other control member, is a particular driving torque applied to the ratio-varying components ("variator") A connection (21, 22) between at least one of the variator sheaves (3, 4) and its shaft (5) is torque-sensitive, so that torque at that sheave generates an axial force which is a function of the magnitude and direction of the torque to which the sheave is subjected. Examples are described in which the operating axial load, applied to the variator pulley units, comprises two parts--a first part to maintain traction between sheaves and band, and a second part related to the applied torque--and a variator using more than one band.

Abstract: A continuously-variable-ratio transmission ("CVT"), especially of the toroidal-race rolling-traction type, in which the prime mover is connected to the ratio-varying component ("variator") by a torque converter or other starting device capable of slip. The CVT output is connected both to the variator output and also, by way of fixed ratio gearing and a one-way clutch, to the output of the starting device. At low speeds drive is transmitted from prime mover to the CVT output by way of the fixed ratio gearing in both forwards and reverse. In forward drive, as the speed of the variator output rises, operation of the one-way clutch causes the drive transmission path to change from the fixed ratio gearing to the variator output once the speed of the latter exceeds the former.

Abstract: A continuous-variable ratio transmission comprising a ratio-varying unit ("variator"), and an epicyclic unit having three outputs arranged concentrically. Two of those outputs are connected respectively in fixed ratio to opposite ends of the variator, so that as the variator ratio changes, the speed of one of these outputs always rises and that of the other falls. These two outputs are also connected by appropriate gearing and clutches to the CVT output shaft. Successive regimes of operation, so extending the overall ratio range of the CVT, are obtained by alternatively connecting each of the two epicyclic outputs to the CVT output. Ratios and other parameters are chosen so that regime changes are synchronous.

Abstract: A continously-variable-ratio transmission ("CVT"), for instance of the toroidal-race rolling-traction type, capable of geared neutral and of operating in at least two regimes and including a ratio-varying component ("variator"), a power-recircuiting epicyclic, a final drive shaft connectable with the variator by way of one of two alternative driven shafts and an input epicyclic the input of which is connectable to a prime mover and the two outputs of which are connected to the two alternative driven shafts respectively. One of the regimes includes a "geared neutral" condition, and the power-recirculating epicyclic is associated with clutches whereby power is recirculated through it in that regime. In the remaining one or more regimes no power is recirculated within that epicylic, but drive reaches the CVT output by way of appropriate clutches and whichever of the two driven shafts will rise in speed as that regime proceeds.

Abstract: A roller-control unit for a continuously-variable-ratio transmission of the toroidal-race rolling-traction type, in which the roller carriage (10, 14) is connected by a pivotal joint (30) to the piston (15) of a hydraulic piston-and-cylinder unit (15, 16). The piston (15) is double-acting, and the piston/cylinder contact is the only locus through which the roller carriage (10, 14) makes contact with the fixed structure of the transmission. The piston (15) may have an inner part (32) to which the roller carriage (10, 14) is jointed, and a sleeve-like outer part (33, 34) which makes the necessary sliding and sealing contacts with the cylinder (16), but allows the roller carriage (10, 14) the necessary freedom of pivoting movement during use.

Abstract: A continuously-variable-ratio transmission (CVT) of the toroidal-race rolling-traction type, capable of operating in "low" and "high" regimes with synchronous change between those regimes, and including a variator (3)--that is to say a ratio-varying component--and an associated gearing set (2) of which the components are capable of being set in different combinations for the high and low regimes, in which the output of the gearing is connectable to the output (1) of the CVT as a whole, and the gearing has first (25) and second (29) inputs connected with the variator output (19) and engine output (5) respectively, and in which in low regime the gearing is set to recirculate power and so deliver to its output a power equal to the difference between its two input powers, whereas in high regime it is set to as to split the power flow and to deliver to its output a power representing the sum of the powers at its two inputs.

Abstract: A roller control system for a CVT of the toroidal-race, rolling-traction type in which a roller assembly comprises a roller (1) mounted in a carriage, and in which operating mechanism (10) contacts and applies a predetermined control force to the carriage whereby to control the manner in which its roller transmits torque and ratio between the two dics with which it is in contact, and in which the roller assembly is located by only three contacts with adjacent components namely the two disc/roller contacts and the contact with the operating mechanism. The roller centre (6) can move along the roller axis (5) relative to the carriage, and the carriage and the operating mechanism are connected by way of a hinged joint (7) with a single degree of freedom. The preferred operating mechanism is of piston (11, 12) and cylinder (13, 14) type. The axis (8) of the hinge may lie between the operating mechanism and the roller, or (e.g. at 40, FIG. 4) may pass through the operating mechanism itself.

Abstract: A continuously variable transmission with coaxial input (from 6) and output (17), capable of operating in at least two regimes, and having a variator (2) of the toroidal-race rolling-traction type, and gearing including both a speed reducing unit (10) and an epicyclic mixing gear unit (15) in which the components of the mixing gear unit are locked up in at least one of the regimes, and in which the speed-reducing unit (10) effects its speed-reduction without reversal of the direction of rotation between its input (1) and output (from 26). The operating axis (5) of the variator (2) may either coincide with the coaxial input and output of the transmission (FIG. 2 ) or be parallel to but displaced from it (FIG. 3 ). In addition to a brake (13) and a clutch (20), operable to engage first and second regimes, a further clutch (48) operable to engage a third regime is shown.

Abstract: A roller control system for a continuously-variable-ratio transmission of the toroidal race, rolling traction type, in which rollers (60) of variable orientation transmit traction between a part-toroidal race (85) formed on an input disc (61) and a similar race (87) formed on a coaxial output disc (62). Each roller is mounted to rotate about a fixed centre (66) and a fixed axis (58) within a rigid carriage (67), one end of which contacts operating mechanism reciprocable over a predetermined stroke of operating movement and operable to apply a control force to the carriage. The assembly of roller and carriage is located by only three contacts with adjacent structure, namely the two disc/roller contacts (86, 88) and the contact (82) with the operating mechanism.

Abstract: A ratio-varying component for a continuously-variable-ratio transmission of the toroidal-race rolling-traction type, in which each roller (20) spans the toroidal clearance between its respective input (4, 5) and output (11, 12) discs diametrically and the roller center (20b) is capable in operation of limited movement back and forth along the center circle (22a) of the clearance, and in which stop means (40, 41; 30, 33) are mounted adjacent both the outer and inner edges of the part-toroidal races (22, 23) on the discs, to prevent the rollers from running off the edges.

Abstract: A ratio-varying component for a transmission of the toroidal-race rolling-traction type, in which each of the rollers (1) transmitting torque between an input disc (51, FIG. 3) and a corresponding output disc (40) is positioned hydraulically by means of an attached hydraulic piston (5) and cylinder (6) combination, in which all the cylinders lie to the same side of a common plane (43a) including the axis (43) of the discs. The cylinders may be supported on a common block-like structure (41), in which hydraulic conduits (31a, 32a, 37a, 44) may be contained.