Eaton's gearbox for the Nineties
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EATON'S SNAPPER gearbox will be introduced in Europe on August 1, and according to an Eaton spokesman last week all but one of the British vehicle manufacturers have contracted to fit the box in test vehicles.
First introduced at the Frankfurt Show in 1974 Eaton describe the Snapper as being neither automatic nor semiautomatic. "It is a new concept," said Mr Bud Richards of the Eaton Transmission Division last week.
" It is a mechanical transmission that shifts itself when it reaches the correct speed in a driver selected gear. It just won't accept a gear unless it is ready to. It's about as foolproof as you could want."
The Snapper has three gear ratios in each of its four forward and reverse gears. They are low, intermediate and high and are selected with a button placed on top of the gear shift lever knob. The shift mechanism consists of a spring loaded jaw clutch with a blocking member.
To select a gear a conventional shift block moves the gear into its engaged position. If the mating jaw clutch on the main shaft is rotating at a diffirent speed the blocker pushes it against the springs and prevents it from making contact. The speed difference between gear and blacker holds the blocker in position until the gear reaches the same speed as the blocker. Then the jaw clutch is released and the gear is engaged.
The driver makes button shift between low, intermediate and high in each of the four lever positions to obtain 12 progressive speeds.
He selects the three positions in turn in first gear then returns the button to low, moves into second and then moves the button to intermediate and high. This sequence is continued through the box.
Fast change
The clutch need only be used for starting, on inclines or when a fast change is necessary. All other changes are pre-selected.
To make the changes the engine is run-up, the button is moved, the throttle is released until the shift is made and the throttle is reapplied.
Eaton claim that although the box will cost about 15% more than the Roadranger it will save about 20% on maintenance costs. Production starts at the company's St Nazaire plant next year and in 10 years' time the Snapper will be Eaton's only gearbox. SPECIFICATIONS: Model TS1312-A. For on-highway vehicles with engines up to 335 kW 450 hp. Torque capacity-1765 Nm (1300 lb ft). Speeds-12 progressive forward, 3 reverse. Clutch brake —furnished for use with pulltype, two plate clutches. Clutch housing size—SAE No 1. Power take-off-bottom: six bolt type mounted on an eight bolt adapter plate, turning at .970 engine speed. Length-90 cm (35iin) from face of clutch housing to end of splines c output shaft. Weight-3481i (7661b) with SAE No 1 clutc housing. Oil capacity-16 litres (29 pints).
GEAR RATIOS: Gear, 12t1 Ratio, 1.00, 11th, 1.24; 10t1 1.55; 9th, 1.93; 8th, 2.40; 7t1 2.99; 6th, 3.77; 5th, 4.68; 4t1 5.84; 3rd, 7.22; 2nd, 8.97; is 11.19. Reverse Ratios: High6.56. Int.-8.16. Low-10.17.