Royal Enfield 500 TWIN 1949, Workshop Maintenance Manual

Page: 74 / 110

ROYAL ENFIELD WORKSHOP MANUAL
SECTION J3
Front Fork
With Facia Panel and Aluminium Alloy Bottom Tubes
Used on " 500 Bullet," 1953 ; "Meteor 700," 1953
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 and to the fork
crown. Fitted over the lower end of the main tube is
the bottom tube made of high strength aluminium
alloy with an integral lug which carries the wheel
spindle. Fitted on the lower end of the main tube is a
steel 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 threaded
housing which contains an oil seal. 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 between the spring stud and the bore of the
valve port forming a hydraulic damping system. A
compression spring is fitted inside the main tube
between the upper end of the spring stud and the
upper end of the main tube. The main tube and upper
end of the bottom tube are protected by a one-piece
cover secured to the fork crown and carrying a
pressed steel lamp bracket welded to it.
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 steering damper and have stronger
springs.
2. Operation of Fork
The fork provides a range of movement of 6 in.
from the fully extended to the fully compressed
position. The movement is controlled by the
compression spring and by the hydraulic damping
system. The hydraulic damping is light on the bump
stroke and heavier on the rebound stroke, thus
damping out any tendency to pitching or oscillation
without interfering unduly with the free movement of
the fork when the wheel encounters an obstacle.
Section J3 Page 1
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