Q As an owner-driver about to
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buy my first brand-new tractive unit, lam .somewhat mystified b.-1 the different types of gear selection available. Just what is the difference between a range-change, splitter ana two-speed a.vle transmission?
A A splitter is used to provide intermediate ratios in what would otherwise be a wide-ratio gearbox. The splitter gears are normally installed ahead of the gearbox main body and they provide an alternative, lower ratio between the input shaft and layshaft.
The splitter is pre-selected from a button, normally on the gear lever, and the ratios, in ascending order, run from 1st low. 1st high, 2nd low, 2nd high and so on. Practised drivers do not usually use each split, instead they will override the control as traffic and road conditions dictate.
The range-change gearbox comprises a close ratio, normally four-speed, main unit with a rangechange auxiliary gear at the rear of the main unit. The range-change auxiliary section is driven from the main section output shaft and the gearbox torque throughput can be increased, without overloading the main-section gears or bearings, by altering the range-change gearings. Torque throughput in the main section is the same for each range. The gear change sequence is the same in each range, but before moving between them, the appropriate range is preselected from a button. normally on the gearstick. Typically. one would move away from rest with low range selected and change ur through 2nd, 3rd, 4th positions, then select high range and "re-use" the same gear positions to get 5th, 6th. 7th and 8th.
Using a two-speed axle provides a similar effect to that of a splitter gearbox.