Two-speed Axle for Leyland Comet A TWO-SPEED axle with vacuumchange speed
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control is now being offered by Leyland Motors, Ltd., as an alternative to the standard hypoid-bevel rear axle on the haulage, tipper, and tractor models of the company's Comet range of vehicles. Basically, the axle is a combination, in one unit, of a single-reduction axle and a doublereduction axle which gives alternative
ratios of 5.14 to 1 for the high gear, and 7.15 to I for the low.
In high gear th.'t axle functions as a single reduction unit, the reduction being obtained through a bevel pinion and crown wheel in the normal way. When in low gear, planetary gears come into operation giving a further reduction. The axle then functions as a double reduction axle, the first reduction being through the pinion and crown wheel, and the second through the epicyclic gearing.
Control for the axle, which has a casing made up from a two-piece steel pressing, is effected by a pull-and-push lever, mounted on the main gear-shift lever, which supplies vacuum Ao a large diaphragm-type vacuum cylinder. This cylinder is mounted on the axle casing and operates the gear-shift lever in the axle.
When the engine is stopped, or should the vacuum supply fail for any other reason, the speed is automatically returned to the low gear position by a spring fitted in the vacuum cylinder. Only when subjected to the vacuum control can high gear be engaged.
All working parts of the axle are lubricated by a system of forced flow lubrication.
Working in conjunction with the Comet five-speed helical gearbox, the axle thus provides 10 ratios which, apart from an increase in performance. will also result in economy in fuel and oil as well as reduce wear on engine and transmission.