Royal Enfield 350 BULLET 1949, Руководство по техническому обслуживанию мастерской

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ROYAL ENFIELD WORKSHOP MANUAL
SECTION J4
Front Fork
With Facia Panel and Steel Bottom Tubes
Used on "350 Model G," "500 Model J2," 1951 onward:
" 350 Bullet," " 500 Twin," 1950-53 inclusive
1. Description
The telescopic fork consists of two legs each
of which comprises a main tube of chrome
molybdenum alloy steel tubing which is securely
clamped to the facia panel fork head at the upper
end and to the fork crown. Filled over the lower
end of the main tube is the bottom tube made of
steel tubing with a forged steel fork end
flash-welded to it.* Fitted on the lower end of
the main tube is a bronze bush which is a close
fit in the bore of the bottom tube. The upper end
of the bottom tube carries a bronze bush which is
a close fit over the outside diameter of the main
tube. The bush is secured to the bottom tube by
means of a gland nut with an oil seal fitted inside
it. A stud, known as the "spring stud," is fitted in
the lower
end of the bottom tube and a valve port
is secured to the lower end of the main tube. As
the fork operates oil is forced through the
annular space between the bore of the valve port
and the outside diameter of the "spring stud,"
which is formed with a double taper. Thus
hydraulic damping is provided which is light at
the normal position of the fork and becomes
increasingly effective towards each end of the
fork's travel. A compression spring is fitted
inside the main tube and is secured by scrolls so
that it is in tension on the rebound. The lower
end of the main tube and upper end of the bottom
tube are protected by a cover tube screwed to the
fork crown. The upper end of the main tube is
covered by a tube with a pressed steel lamp
bracket welded to it.
The fork is filled with a light oil (S.A.E. 20)
up to a level above the valve port, this oil
providing both the damping medium and the
lubricant for the bearings.
A special version of the fork is available for
sidecar use. This has a modified fork head and
fork crown setting the main tubes 1.1/2 in.
further forward, thus giving less trail and
providing lighter steering when used with a
sidecar. These sidecar forks also are fitted with a
*On early models the fork end was made of
aluminium alloy screwed on to the bottom tube.
steering damper and have stronger springs.
2. Dismantling Fork to Replace Spring, Oil
Seal or Bearing Bushes
Place the machine on the stand and in the
case of Model "G" or "J2" place a box beneath
the crankcase to raise the front wheel from the
ground. Disconnect the front brake control and
remove the front wheel and mudguard complete
with stays. Unscrew the oil level plug after
placing a tray to catch any oil which may run
out. Undo the nut which secures the spring stud
to the fork end and knock the spring stud
upwards into the fork with a soft mallet, thus
allowing the remainder of the oil to escape.
Unscrew the outer cover tube using the hand
grips E4912 thus exposing the gland nut which
can be unscrewed with the hand grips E5417
using a bar through the bracket for the wheel
spindle to prevent the bottom tube from
turning. The bottom tube can now be
withdrawn completely from the main tube
leaving the bottom tube bush, oil seal and gland
nut on the main tube.
Now unscrew the main tube valve port using
"C" spanner E5418. The spring stud and spring
can now be withdrawn from the lower end of the
main tube.
The bronze main tube bush can be now
tapped off the lower end of the tube using the
bottom tube bush for this purpose. The bottom
tube bush, oil seal and gland nut can then be
withdrawn.
3. Spring
The original length of the spring is 19 in.
overall. A new spring should be fitted if the old
one has set by more than 1 inch.
4. Steering Head Races
The steering head bearing consists of two
deep groove thrust races each containing 19 x
1/4” diameter balls. The bearing is adjusted by
Section J4 Page 1
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