A.J.S. 16MS, Instruction Book

Page: 52 / 94

Illustration 17
Introduced in early 1941, for use under strenuous war conditions by all the allied armies.
It remains unaltered, except in detail, to this day, and copied practically universally. The
hydraulic dampers operate in tubular members located inside the main tubes. As will
be seen the aluminium sliding members operate upon steel bushes attached to the bottom
ends of the main tubes and also upon bakelite bushes, secured to the top end of the
sliders themselves. Above these bushes, an oil seal is fitted, the object of which is to
prevent leakage of oil from below into the main spring chamber. The normal level of
oil is well above the bottom extremity of the main inner tubes and bearing this in mind,
it is at once clear that upward movement of the sliders resulting from impact with road
bumps in addition to meeting resistance from the main springs also causes oil to be ejected
by the close fitting steel bushes. This oil is forced upward through the open ends of the
main inner tubes and also through the holes A (Illustration 17) in the bottom of the
damper tubes, then 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
forming an air buffer acting as auxiliary to the main springs. This displacement of
oil upon impact imposes a certain amount of damper effect, the extent of which
increases with the violence of the shock, or in other words, the bigger the bump
the greater the damping effect. Upon the recoil movement, the damper disc valve
returns to its seat and the oil trapped between this valve and the plunger sleeve above
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