Triumph TR6 PI Operation Manual page 278

WORKING PRINCIPLES
The overdrive gears are epicycle and consist of a
central sunwheel meshing with three planet gears which in
turn mesh with an internally toothed annulus. All gears are
in constant mesh. The planet carrier is attached to the input
shaft and the annulus
is
integral with the output shaft.
The unit is shown diagrammatically in PT 3355.
An extension of the gearbox mainshaft forms the
overdrive input shaft. Forward direct drive (PT 3355)
power is transmitted from this shaft to the inner
member of
uni~directional
clutch and then to the outer
member of this clutch through rollers which are driven up
inclined faces and wedge between the inner and outer
members. The outer member forms part of the combined
annulus and output shaft.
The gear train is inoperative. A cone clutch is
mounted on the externally splined extension of the
sunwheel and is loaded in contact with the annulus by a
number of springs which have their reaction against the
caSing of the overdrive unit. The spring load is transmitted
to the clutch member through a thrust ring and ball
bearing. This arrangement causes the inner friction lining of
the cone clutch to contact the outer cone of the annulus
and rotate with the annulus, whilst the springs and thrust
ring remain stationary. Since the sunwheel is splined to the
clutch member the whole gear train is locked, permitting
over-run and reverse torque to be transmitted by the cone
clutch, without which the uni-directional clutch would give a
freewheel condition. Additional load is imparted to the
clutch member, during over-run and reverse, by the
sunwheel which, due to the helix angle of its gear teeth,
thrusts rearward and has for its reaction member the cone
clutch.
2
IN DIRECT DRIVE
KEY
1. Sunwheel.
2. Sliding cone clutch.
3. Spring pressure.
4. Annulus and sunwheellocked.
5. Arinulus.
6. To propshaft.
7. Uni-directional roller clutch.
8. Planet wheels.
4O.00.07J
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Triumph TR6 Manual. Part No. 545277 Issue I ~
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