Patent GB-528508-A (GB)
Title: Improvements in or relating to power transmissions for motor vehicles
IPC: B60K17/08
Filed: 1939-01-31
Abstract: 528,508. Variable-speed gearing; servo-motors. CHRYSLER CORPORATION. Jan. 31, 1939, No. 3286. Convention date, May 13, 1938. [Class 80 (ii)] [Also in Group XXIX] A vehicle transmission system comprises a two-speed planetary gear C in combination with, and arranged in front of, a two-speed countershaft gear D. The annulus 34 of the planetary gear is secured to the driving shaft 28 and the planet carrier 40 is in continuous driving connection with a driven intermediate shaft 33 through a clutch member 47 which engages teeth on hubs 43 and 50 of the carrier and shaft respectively. The sun gear 52 is free on the driving shaft and is prevented from backward rotation by means of an over-running clutch or brake device F to allow a reduced drive to be transmitted to the driven shaft. The planetary gear is adapted to be locked solid to give a direct drive by a sliding movement of the clutch member 47 to engage a toothed clutch member 63 secured to the driving shaft 28, a baulking ring 65 being provided to ensure synchronization of the two parts before engagement. A second over-running clutch device G is provided between the sun gear and the shaft 28 so that in the reduced drive the speed of the driving shaft and the engine is prevented from falling below that of shaft 33. The clutch member 47 is operated from a suitably arranged control knob on the dash. The countershaft gear D comprises a gear 93 on the shaft 33 which drives a countershaft group 95, 97 and 98 and is adapted to be clutched direct to the tail-shaft 100 by means of a synchronized clutch device 111 to give a direct drive. A reduced drive is obtained by sliding a gear 105 on shaft 100 into engagement with the gear 97 on the countershaft and reverse is obtained by engaging it with a reverse idler 99. Four speeds are thus obtained by the combination of the two gears. A normal friction clutch (not shown) is provided for releasing the drive between the engine and shaft 28. In the arrangement in Figs. 5 and 9 a double planetary gear C<1> is utilized in combination with a reversing gear D<1>, whilst a hydraulic coupling B<1> is employed instead of a normal friction clutch. In this arrangement the first planetary train is as before, the annulus 129 being secured to the driving shaft 124, the sun gear 135 being adapted to be held by an overrunning clutch device F<1> and the planet carrier 132 serving as the driven member. In this instance however the carrier 132 forms the annulus 221 of the second planetary train which includes stepped planet pinions 222 mounted on a carrier 226 secured to the driven shaft 134, the sun gear 227 being prevented from backward rotation by an over-running clutch device L. The first train gives two speeds as before, the direct drive being obtained by engagement of a friction clutch H arranged between the sun gear 135 and the driving shaft 124 and actuated by fluid pressure on a piston 172. A reduced drive through the second train is obtained by holding the sun gear 227 from backward rotation whilst direct drive is obtained by the engagement of a centrifugal clutch M between the carrier 226 and the annulus 221 which is automatically brought into action on the vehicle attaining a predetermined speed, for example, 10-15 miles per hour, and the engine being momentarily slowed down by release of the accelerator pedal. The first speed is obtained with both trains in the reduced drive, second speed on increase of speed of the vehicle by the centrifugal clutch M locking the second train and a third speed by operation of the clutch H of the first train which may also be automatic and is controlled by a valve means K. Oil is supplied under pressure to operate this clutch from a pump N driven at a speed proportional to that of the vehicle so that at a predetermined speed, for example, 25 miles per hour, the clutch is automatically engaged for direct drive. The vehicle speed at which this operation takes place can be varied by means of a bye-pass valve at the valve means K which can be actuated from a knob 297 situated on the dash. This direct drive clutch operation can also be over-ridden by a main control valve at K which is operated from a selector control lever 212 on the steering column to maintain the first planetary train in reduced drive. A second lever serves for selecting forward, reverse, or neutral and operates on a reversing gear mechanism D<1> to clutch the shaft 134 direct to the tail-shaft 125 by a clutch member 261 or to bring a reversing train into operation or to leave the clutch member in a neutral position. The outer ring 148 of the over-running clutch device F<1> for preventing backward rotation of the sun gear 135 is itself normally held by a brake J. This brake is however adapted to be released by fluid pressure derived from a piston 162 actuated by a foot-pedal 168, which pressure acts on pistons 159 to release the brake, so that the drive from shaft 124 to the driven member 132 of the first planetary train can be completely interrupted despite the unavoidable drag through the fluid coupling so as to facilitate the engagement of the forward or reverse gears when the vehicle is at a standstill and to accelerate the vehicle. The direct drive obtained by the engagement of clutch H is arranged to be equivalent to an overdrive ratio which can be entirely excluded by operation of selector control 212 but when in service is subject to automatic control. The arrangement shown in Fig. 4 may be modified by the substitution of a fluid coupling in place of the normal friction clutch and the outer member of the over-running clutch device F may be held by a releasable brake so that the drag effect of the coupling can be negatived as previously described. Specification 528,561 is referred to.