Patent GB-458533-A (GB)
Title: Control mechanism for toric race variable-speed transmissions
IPC: F16H15/38
Filed: 1935-12-06
Abstract: 458,533. Variable - speed gearing. GENERAL MOTORS CORPORATION, Grand Boulevard, Detroit, Michigan, U.S.A. Dec. 6, 1935, No. 33842. Convention date, Dec. 20, 1934. [Class 80 (ii)] Control mechanism for toric-race and roller variable-speed gear comprises two roller control systems for effecting change of ratio during forward drive and reverse, and means by which one or the other system may alternatively be selected. Said systems act upon the roller carriers on opposite sides of the roller axis and, in the particular apparatus described, viz, a drive for a motor vehicle, are brought into action automatically according to the direction of running. Within a casing 10 is a supporting frame comprising separated transverse members 12, 12<a> united by a web 14 and having holes to receive bearing elements 16, 16<a> spaced apart to receive a friction clutch and provided with trip projections 17, 17<a> co-operating with the clutch. The members 12, 12<a> have openings 72 to admit the transmission rollers 70, 70<a> interposed between races 52, 52<a> and 64, 64<a>. Input shaft 20, Fig. 6, is journalled in an extension shaft 20<a> carrying a gear 22 engaging a gear 60 which drives the races 64, 64<a> through balance or differential devices such as rollers 66. A clutch member 24 secured to shaft 20<a> extends over the rear end of shaft 20 and has internal teeth 26. A reverse gear 28 with hub 30 having external teeth 32 is slidably keyed to shaft 20. The output shaft 40 has a bevel pinion 46 to engage the vehicle differential and carries a gear 48 to engage with gear 28 to reverse. The front and rear races 52, 52<a> are secured to shaft 40. The gear 60 is secured to a hub 62 which journals on the elements 16, 16<a> and forms also a bearing for the races 64, 64<a>. The rollers are mounted in carriers 80, Fig. 2, which are forked and each of which is attached to member 12 or 12<a> by a universal joint 82. The limbs of each carrier have aligned bearings 100, Fig. 1, for the axle 104 which is inserted through lateral gaps 102, Fig. 6, disposed toward the driving race, the inner ends of bushings 106 being spaced apart a distance greater than the thickness of the rollers. During forward driving the tangential forces between race and roller act away from the joint 82 so as to cause the carrier to trail, and a like trailing action occurs in reverse drive, although the races 64, 64<a> and rollers are free. The ratio position of the rollers both in forward and reverse drive is controlled as follows :-A control shaft 110 actuated manually or by a governor or servomotor, carries at each end an arm 114, Figs. 1, 2, and at the rear end an arm 116. A control tube 130, Figs. 1, 4, disposed within the bearing elements 16, 16<a> is prevented from moving axially by spring rings 131 and has a bearing 132 on output shaft 40. At each end of the tube is a pair of collars 136, 136<a> with internal end conical portions 140, and both may rotate on tube 130. Each collar has a flanged end provided with lugs 144, 144<a> connected by links 156, 156<a>, Figs. 1, 2, with the roller carriers 80 on opposite sides of the roller axis. Collars 136, 136<a> have opposed rectangular flared notches 146, 146<a>, Fig. 1, which act as clutch dogs to engage diametrically opposed dogs 148, 148<a> on automatically controlled coupling rings 150, Fig. 1. The collars 136 and links 156 control the rollers for forward, and the collars 136<a> and links 156<a> for reverse driving. The links 118, Fig. 2, connect arms 114 to the dogs 148<a> on the rings 150, which are automatically coupled with the control collars 136 for forward, and with collars 136<a> for reverse driving in the following manner. Control tube 130, capable of slight rotation in either direction, carries balls 164 engaging internal grooves in couplings 150, these grooves having helical portions 160, Fig. 4, merging into circular portions 162. When the balls 164 are midway of the circular portions, the coupling 150 should be in complete engagement with either collar 136 or 136<a>. The helical grooves in the front and rear rings 150 are of opposite hand, so that by rotation of tube 30 the dogs on rings 150 can be made to interlock either with collars 136 or with collars 136<a> to adjust the ratio position of the rollers in forward or reverse drive, one set of collars being entirely free when the other set is engaged. The tube 130 is automatically rotated to cause a ring 150 to engage either of collars 136 or 136<a> as follows :-A helical clutch spring 170, Fig. 1, encircles the central portion of tube 130 and lies between said tube and the hub 62 with which it is normally in light contact. The spring has thickened end portions 172 adapted to thrust against spring abutments 174, 174<a> on tube 130. The trips 17, 17<a> are adapted to engage the shoulders on the thickened spring ends 172 and are spaced angularly sufficient to permit rotation of tube 130 to disconnect completely the coupling rings 150 from collars 136 and connect them with collars 136<a> or vice versa. For reverse running, gear 28 is engaged with gear 48, and the shaft 40 and races 52, 52<a> rotate counter-clockwise (viewed from the left in Fig. 1), races 64, 64<a>, gear 60 and hub 62 rotate clockwise, and gear 22 and shaft 20<a> counter-clockwise. Since hub 62 now turns clockwise, the spring 170 is forcibly expanded to engage the hub and rotate with it, the left-hand end of the spring leaving abutment 174 and the right-hand end pressing on abutment 174<a> and rotating the tube 130 clockwise, thus withdrawing rings 150 from collars 136 and releasing the controls for forward drive and connecting those for reverse. When tube 130 has rotated far enough to change the control connections, the shoulder on left-hand end of spring 170 engages trip 17 and causes the spring to contract and be released from hub 62. If now clutch elements 32, 26 be engaged for forward drive, the tube 130 is rotated counter-clockwise to release the reverse control collars 136<a> and engage control collars 136 for forward drive. The systems thus brought in automatically then form part of the main control for the rollers actuated from shaft 110.