Royal Enfield 250 CLIPPER, Workshop Maintenance Manual

Page: 31 / 96

ROYAL ENFIELD WORKSHOP MANUAL
PAGE 31
Gearbox and Clutch
1. Description of the Clutch
Early Models
The clutch is built into the clutch sprocket and is
mounted on the gearbox mainshaft which projects
through into the primary chaincase.
There are four driven plates which are plain and
three driving plates, giving six friction surfaces.
The driven plates comprise the clutch centre
backplate, two plain plates on splines on the clutch
centre and the clutch front plate.
The driving plates comprise the clutch sprocket
itself which has a Klingerite ring riveted to each side
and two pierced plates which rotate with it and which
are fitted with cork inserts.
The clutch plates are held in contact, when
driving, by three coil springs in the case of the "250
Clipper" and "Crusader 250" models, and six coil
springs in the case of the "Crusader Sports," and are
released when the springs are compressed by a pad
and rod which passes through the centre of the
gearbox mainshaft.
Later Models
All later models retain a clutch basically similar to
the earlier models, but incorporating five driven
plates which are plain, and four driving plates giving
eight friction surfaces.
The splined sections on the clutch sprocket, and
the clutch centre are longer, and the clutch front
plate has a shallower recess for the withdrawal pad
than the early type.
On some models the plates are not pierced but
have friction material bonded to their surfaces.
All later models have three pressure springs.
350
c.c. Model
This clutch employs six driven plates, which
comprise the clutch centre back plate, four plain
plates and the clutch cover plate.
There are five driving plates including the clutch
sprocket, each with friction material bonded to their
surfaces. Three pressure springs are used.
2. Descripion of the Gearbox
The gearbox itself is cast as part of the crankcase,
but forms a separate compartment housing the
mainshaft, mainshaft sleeve, layshaft and gears.
On early engines the gearbox "breathes" through
a small hole in the filler plug and on later ones
through a hole in the gearbox cover, connecting
the top of the gearbox to the generator
compartment on the offside.
Four-speed Gearbox
(See Fig. 2 for operation).
The clutch sprocket A is mounted on the end
of the mainshaft B which passes through the
mainshaft sleeve C on the end of which is the
final drive sprocket D.
At the other end of the mainshaft B is a pinion
E which engages with a pinion F on the layshaft
G. At the other end of the layshaft G is a pinion
H engaging with a pinion J which runs free on the
mainshaft sleeve C.
The mainshaft sleeve C has splines on which
slides a double pinion KL. This double pinion KL
engages with two pinions M and N which are free
to rotate or slide on the layshaft G.
The double pinion KL has dogs at each end
which can engage with dogs on the pinion E or on
the pinion J.
The pinions M and N have internal dogs which
can engage or slide over projecting dogs P and Q
on the layshaft G.
The double pinion KL and the pinions M and
N all slide together and are moved by the operator
E11
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