Front Fork; Operation Of The Fork; Section Of Fork Leg - Royal Enfield 350 BULLET 1949 Workshop Maintenance Manual

ROYAL ENFIELD WORKSHOP MANUAL
With Casquette and Aluminium Alloy Bottom Tubes
1. Description
The telescopic fork consists of two legs each of
which comprises a
molybdenum alloy steel tubing which is screwed into
the Casquette fork head at the upper end and
securely clamped 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 mean, 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 lower end of the
main tube and upper end of the bottom tube are
protected by a cover secured to the fork crown.
A special fork is available for sidecar machines.
This has bottom tubes with extended wheel lugs
giving less trail and is fitted with stronger springs
and a steering damper.

2. Operation of the 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.
The fork is filled with a light oil (S.A.E. 20) to a
point above the lower end of the fork spring so that
the damper chamber "B" is always kept full of oil.
SECTION J1

Front Fork

main tube of chrome
Section J1 Page 1