Patent GB-1232341-A (GB)
IPC: F16H37/04
Filed: 1969-02-03
Abstract: 1,232,341. Change-speed gear; retaining gear-wheels on shafts. WHITE MOTOR CORP. 3 Feb., 1969 [26 Feb., 1968], No. 5764/69. Headings F2D and F2U. A transmission for a heavy vehicle comprises auxiliary countershaft gear-trains 20 driving selectively the sun 10 or ring 12, separately or together at different speeds, of a three-element planet train having an output carrier 14, to provide, by various combinations of clutches A . . . J, and two brakes KL, a possible twentyeight forward ratios (one direct drive, all others reduced) and four reverse, the ratios actually available to the operator, e.g. five to fifteen forward and one reverse, being determined by a plug-in electrical control unit the selectable ratios of which are pre-chosen to suit the terrain in which the vehicle is intended to operate, whereby one basic gear unit satisfies all conditions. Mechanical, hydraulic or pneumatic actuation may alternatively be used. Gear arrangement.-Identical parallel loadsharing countershafts 20, described collectively in the Specification as a first countershaft means, each carry fast thereon five wheels 30 . . . 40, meshing respectively freely rotatable wheels 28, 32 dog-clutchable at A, B to an input shaft 18, and wheels 35, 38, 42 similarly clutchable at F, G, H to a floating tubular shaft 25, described in the Specification as a second countershaft, concentric with aligned input and output shafts 18, 16 and surrounding an inner sun-shaft 22 to which the wheel 32 can also be clutched at C. The ring gear 12 can be clutched at J to the tubular shaft 25 and, for reverse, countershaft idlers 44 are arranged between the wheel 42 and internal teeth 46 in the ring-gear 12. Four operative modes are possible according to the setting of the planet gear, as follows. In mode one, the sun 10 is clutched to the ring 12 by clutches D, J, locking the planet gear. Six forward ratios, including direct-drive high, are obtainable using clutches A. . . G in combinations of four. Mode two applies input drive selectively to the sun 10 with the ring 12 locked by a brake L, providing six further forward ratios, using clutches in combinations of four and three. Mode three applies input drive selectively to the ring 12 with the sun 10 locked by a brake K, for eight further ratios, including four reverse, by combinations of four clutches. Mode four applies input drive selectively to both the sun 10 and ring 12 at different speeds, providing twelve further forward ratios, again using combinations of four clutches. Mounting of the rotatable wheels is shown in Fig. 2 for the wheels 28, 32, freely rotatable on the input shaft 18. The wheels are retained axially by a retaining ring 58, which may be in two halves, retained in a groove in the wheel 28 by a snap ring 62, and located axially on the shaft 18 by splined collars 64, which are turned into and keyed in circumferential grooves in the shaft, with an interposed spacer 65. Control.-Solenoids (70, Figs. 8 and 9, not shown) individually actuate the dog clutches and are wired by a plug-and-socket connector to an electrical control unit having a manuallyoperated wiper bridging groups of three or four contacts leading to the required combinations of clutches in accordance with the ratios chosen for the particular electrical unit. A park switch applies brakes K, L together for park lock. The manual wiper is locked in gear positions, release of the lock (not described) for gear-shift breaking the current supply circuit to neutralize the transmission, facilitating synchronizing.