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Snap changes from Eaton's Snapper
Page 34
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THE Eaton Corporation of America, which includes the Fuller Roadranger gearbox series in its list of products, has developed a new range of heavy-dutyAruck transmissions, Going under the model number of TS-1312-A the new transmission, which is now available in the USA, popularly known as the Eaton Snapper.
It is neither an automatic nor a semi-automatic, but a mechanical transmission which shifts automatically when the synchronising speed is reached. Thus the driver selects the gear and the transmission then shifts itself.
The freedom of choice is still left to the driver, who can double de-clutch, single declutch or not use the clutch at all (except for starting from rest).
The TS-1312-A has four gear-lever positions for forward motion, but they are not arranged in a straightforward H pattern as the reverse gear takes up the place normally occupied by first gear with the high ratio being out on a forward dog leg. Each lever position controls a low, intermediate and high range selected by the switch on the gear lever in a similar manner to the Faller Roadranger boxes in, for example, the Ford Transcontinental and the eightwheeler DAF. This gives 12 forward gears and three reverse.
The clutch is always used to start from rest but then, if the driver prefers, he can merely select the desired gear, vary the throttle, and the transmission will change gear when the correct matching speeds are reached.
The actual change mechanism of the Snapper is extremely straight-forward, consisting of a spring-loaded jaw member in conjunction with a blocking member. When a gear is selected, a conventional selector fork moves the gear into its engaged position. If the mating jaw clutch, which is on the mainshaft, is going at a different speed, the blocker member pushes it back against the spring and prevents it from contacting the gear.
It continues to do this until the correct synchronising speed is reached, when the blocker turns with the gear and releases the jaw.
The Snapper is designed for trucks with power outputs of up to 336kW (450bhp) but as yet is not available for the UK market,