Patent GB-587102-A (GB)
Title: Improvements in or relating to automobile power transmission
IPC: B60K5/08
Filed: 1945-01-03
Abstract: 587,102. Driving gear; regulating. TRIGGS, W. W. (Timken-Detroit Axle Co.). Jan. 3, 1945, No. 274. [Classes 79 (ii), 79 (iii) and 79 (v)] [Also in Groups XXIV and XXVII] An automotive vehicle comprises at least two driving axles, a main engine connected to one axle through a multi-speed axle drive gear, an auxiliary engine connected to another axle through another multi-speed axle drive gear, and a single gear-box interposed between the main engine and its associated multi-speed axle drive gear. Preferably each axle comprises a twospeed gear, and the low speed ratio of the axle driven by the main engine corresponds to high speed gear ratio of the axle driven by the auxiliary engine. Operation of the main gear box over a certain portion of its gear ratio change actuates means for automatically changing the gear ratio of the axle driven by the auxiliary engine, provided the auxiliary engine is running and provided the.other axle drive is in its low speed ratio. The auxiliary engine is brought into and out of operation automatically as the load on the main engine increases and decreases. The vehicle, Fig. 1, comprises a main engine 28 with gear box 32, driving the propeller shaft 34 and a two-speed differential 40 operated by lever 42; and an auxiliary engine 54 driving the propeller shaft 56 and front axle 24, through a two-speed differential 62 operated by 'lever 90. The general arrangement is such that upon operation of the control 262 to select the lower gear ratio in the back axle (by utilising the depression in the main engine inlet manifold 52 via pipes 50 and 46 to work the pneumatic power unit 44) a switch 124 controlling the electric starting system of the auxiliary engine is closed. The auxiliary engine is started when the depression in the main engine manifold is sufficient to operate a second switch 128 in series with the first. The consequent depression in the auxiliary engine inlet manifold is then transmitted by pipe 98 to selector 100 which is interconnected with the gear lever 104, so that according to whether the latter is in fourth (top) or third gear vacuum is transmitted either by pipe 94 or pipe 96 to the pneumatic power unit 92 to select the higher or lower gear ratio in the differential drive. The gear ratios are preferably so adjusted that with the main engine driving the lower differential gear ratio, so described above, fourth gear on the main engine gear box corresponds to the auxiliary engine driving the higher gear ratio of the front axle differential, and third gear corresponds to the auxiliary engine driving the lower gear ratio of the front axle differential. Two-speed differential gear. In Fig. 2 the usual crown wheel is replaced by two spur gears 70, 71 of different diameters in permanent mesh with corresponding pinions 73, 72 mounted freely on the shaft 74, which is driven by bevel gears 76, 78 from the shaft 60. One or the other of the pinions 73, 72 can be driven from the shaft 74 according to the position of the slidable clutch collar 80 which is splined to the shaft and which has dog teeth on both faces which can engage corresponding teeth on one of the pinions. The clutch collar 80 is moved by a fork 86 on actuation of the lever 90. Selector valve 100, Fig. 4, comprises a body portion 152 in which slides the hollow plunger 146 connected by socket 150 to a finger 148 attached to the gear lever of the main gear box. as arranged that engagement of fourth (top) gear moves the plunger to the left, whereby the vacuum pipe 98 from the auxiliary engine is put into communication via port 162 with the pipe 96, whereas pipe 94 is put into communication with the atmosphere via the annular groove 168, port 154 and filter 158. When third gear is engaged the plunger 146 is moved to the right and vacuum is transmitted to the pipe 94 whilst pipe 96 is put into communication with the atmosphere through annular groove 166, port 156 and filter 158. Engagement of other gears on the main gear box leaves the plunger 146 in its central position as shown, and a spring loaded detent is provided to maintain the plunger in position. Pneumatic power unit 92, Fig. 3, which selects the high' or low gear ratio in the differential according to whether vacuum'is admitted to the pipe 96 or pipe 94 by the selector valve described .above, comprises a double sided piston 140 working in a cylinder 138 and moved to the left to select the high gear ratio when pipe 96 is subjected to vacuum and to the right for the low gear ratio when pipe 94 is so subjected. To maintain the piston in its central position until it is required to move, pipe 184 is connected to the main engine inlet manifold and communicates through a restricted opening 190 with a recess formed by a portion of the rod 142 of reduced diameter bounded by two piston members 194, 196 which normally block the ports 198, 200 communicating with the two sides of the piston 140. Should the piston wander from its central position, one or the other of the port; 198, 200 is put into communication with one or the other side of the piston 140 to return the latter to its central position. A pair of opposed springs 206, 208 may also be provided to assist this centralising action. Vacuum operated switch. 128, Fig. 6, comprises a pair of spring-loaded diaphragms 232, 234 providing three chambers in the body 230. The lower chamber is connected with the main engine inlet manifold 52 at a point between the carburettor 250 and the choke tube 248; the middle chamber between the two diaphragms is connected to the choke tube 248 at its smallest diameter. The spring loading on the diaphragms is so adjusted that when the main engine under full throttle can no longer handle the load, the diaphragm 232 is allowed to rise under the action of the spring 260 until contacts 241, 246 meet and the circuit to the auxiliary engine starting mechanism is completed, provided the switch 124 is also closed. If desired, the auxiliary engine may be manually instead of automatically controlled both for starting and gear changing, but for both methods of control the carburetters of the two engines are interconnected. The auxiliary engine is kept warm for easy starting by by-passing water from the main engine radiator to its water jacket. If desired a torque controlling clutch, e.g., a Fottinger coupling, may be provided between the auxiliary engine and its propeller shaft, particularly when the auxiliary engine is manually controlled. Alternatively a one way clutch may be so disposed, or a combination of both as shown in Fig. 10 wherein 54 is the auxiliary engine, 263 a fluid coupling, 264 a one way clutch and 56 the propeller shaft. The one way clutch prevents the auxiliary engine being accidentally driven at excessive speed by the main engine. Specification 572,896 is referred.to.