Triumph TR6 PI Operation Manual page 277

INTRODUCTION
The overdrive is an additional gear unit between the
gearbox and propeller shaft. When in operation it provides a
higher overall gear ratio than that given by the final drive,
crown wheel and pinion.
The primary object of an overdrive is to provide open
road cruising at an engine speed lower than it would be in
normal top gear. This reduced engine speed gives a
considerable reduction in petrol consumption and increase
in engine life. Overdrive may also be used on the indirect
gears to enhance performance or to provide easy and
clutchless gear changing, for example in town traffic.
OYERDRIVE-J TYPE
The overdrive is operated by an electric solenoid
controlled by a switch, fitted in the gear lever knob. An
inhibitor switch is fitted in the electrical circuit to prevent
engagement of overdrive in reverse, and some or all of the
indirect gears.
OVirdrive can be engaged or disengaged at will at any
speed, but usually above 30 m.p.h. in top gear. It should be
operated without using the clutch pedal and at any throttle
opening because the unit is designed to be engaged and
disengaged when transmitting full power. The only
precaution necessary is to avoid disengaging overdrive at
too high a road speed, particularly when using it in an
indirect gear, since this would cause excessive engine
revolutions.
3
4
5
6
PT2.360
KEY
1. Input shaft connected to planet carrier.
2. Sun gear.
3. Annulus.
4. Planet carrier.
5. Output shaft connected to annulus.
6. Roller clutch.
Triumph TR6 Manual. Part No. 545277 Issue I
40.oo.06J