september - october - Fort Sill

THE FIELD ARTILLERY JOURNAL
chamber, hence it serves the double purpose of providing throttling through
the diaphragm in recoil and of controlling counter-recoil.
On recoil, the gun moves to the rear, carrying with it the recoil piston
and piston rod. The oil in the recoil cylinder is forced into the recuperator
cylinder through the opening at the rear of the cradle connecting them. The
oil passes through the valves and throttling opening of the oil regulator, and
moves the floating piston forward against the compressed nitrogen,
compressing it further. As the floating piston moves forward, the tapered
buffer or control rod gradually closes the opening in the oil regulator and
checks the flow of oil until at the end of recoil, the oil flow is completely
stopped.
In counter-recoil the nitrogen expands driving the floating piston to the
rear. It in turn forces the oil through the oil regulator and out of the
recuperator into the recoil cylinder, driving the recoil piston forward, thus
bringing the gun into battery. The flow of oil in its return passage is
regulated by openings in the oil regulator, the flow is gradually slowed
down, returning the gun into battery position without shock. Shock is
further prevented by the respirator.
Before firing, the recoil mechanism should be examined for leakage of
oil, proper amount of oil reserve, that the front end of the recoil cylinder is
clean, and that the slide and roller paths on the cradle are clean and
properly lubricated.
During firing, the action of the mechanism should be watched to see
that the gun returns to battery properly and without shock. Careful attention
should be given to the detection of oil leakage, frequently examining the
following places for leaks; front end of recoil cylinder, the filling and drain
plug hole, the oil index recess, and the right trunnion connection.
Where oil is found to be leaking or seeping, the recuperator must not be
used.
The amount of oil reserve is indicated by the position of the oil index
with reference to the rear face of the recuperator cylinder rear sealing plate.
No Reserve—indicator at the bottom of the recess.
Full Reserve—end of index flush with rear face of sealing plate.
Excess Reserve—index projects beyond rear face of sealing plate.
It is not dangerous to fire the gun with no reserve of oil; however, it
is highly dangerous to fire the gun when the oil index shows excess
reserve.
This mechanism is designed for oil of a certain viscosity, therefore only
the special recoil oil should be used.
The following chart gives a list of recoil mechanism troubles, together
with the causes and remedies:
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