AJS 350 1954, Maintenance Manual And Instruction Book, Page: 54 / 96

Introduced in early 1941 for use under strenuous w a r conditions by all t h e allied armies.
it remains unaltered, except In detail, to this day, and copied practically universally. The
hydraulic dampers operate in tubula r members located inside the main tubes.
As wilI
be seen the aluminium sliding members operate upon steel bushes attached to the b o t t o m
ends of the main tubes and also upon bakelite bushes, secured to the t o p end of the
sliders themselves.
Above these bushes, an oil seal is f i t t e d , the object of which is to
prevent leakage of o i l f r o m below i n t o the main spring chamber. The normal level of
oil is well above the b o t t o m e x t r e m i t y of t h e main inner tubes and bearing this in mind ,
it is at once clear that upward movement of the sliders resulting f r o m impact w i t h road
bumps in addition to meeting resistance f r o m the main springs also causes oil to be ejected
by the close f i t t i n g steel bushes.
This oil is forced upward t h r o u g h the open ends of the
main inner tubes and also through the holes A (Illustration 16) in t h e b o t t o m of t h e
damper tubes, t h e n past the damper disc valve which the passing oil raises off its seat.
As the oil level rises inside the main inner tubes, air trapped is compressed, thereby
f o r m i n g an air buffer acting as auxiliary to t h e main springs.
This displacement of
oil upon impact imposes a certain amount of damper effect, the e x t e n t of which
Increases w i t h the violence of the shock, or in o t h e r words , t h e bigger t h e bump
the greater the damping effect.
Upon t h e recoil movement, the damper disc valve
returns to its seat and t h e oil trapped between this valve and the plunger sleeve above
Illustration 16
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