8 inc Howitzer manual.pdf - Replica Plans and Blueprints

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when elevating the howitzer, the actuating rod pulls upon the short
lever, rotating the cross spindle, bevel segments, piston rod, and piston,
thereby decreasing the orifice between the ports in the piston and the
recoil valve, which is held fast by i ts keys and grooves in the cylinder.
This increases the resistance set up in the recoil cylinder dming recoil,
thereby shortening the recoil of the howitzer. The recoil varies from
60 inches, howitzer horizontal, to 24 inches at 50° elevation, or 0.72
inch per degree of elevation.
UECtJPERATOR.
(Plate XIU.)
The recuperator is of the hyclropneumatic principle and consists of
two liquid cylinders in which work rams, and two air cylinders which
contain both liquid and compressed air. The air cylinders are connected
at their rear ends by an equalizing passage, and are also connected
to the front end of the liquid cylinders by an annular recess
around the latter, along which the liquid passes on recoil and counterrecoil.
The liquid cylinders are closed at the rear end by perforated caps
which are held by pins. The perforations allow any liquid which may
get by the piston to get clear, otherwise the howitzer wo uld not return
fully to firing position after recoil. They also prevent a vacuum forming
in the rear of the recuperator ram.
The front ends are closed by stuffing boxes, packing and caps in
much the same manner as the recoil cylinder. Internally near its
front end, each cylinder is reduced in diameter to form a seat for a
throttle valve, which fits loosely around the piston rod and is kept to
its seat by a helical spring, one end of which bears against the valve and
the other end against the inner face of the stuffing box.
The valves are provided with a coned bead to fit tightly on their
seat. Holes are bored through the head to allow liquid to pass back
into the cylinders after recoil.
The recuperator piston rods are of steel ; their front ends are seemed
by a screwed sleeve inside and a nut ou tside to the cradle cap, while
their inner ends are provided with a packed piston. The packing consists
of two U-shaped leathers properly h eld by supporting rings and
secured by a nut, also a ring of h emp packing, which is kept tightly
against the piston proper by a helical spring h eld by a nut.
The piston rods are hollow; and the front end of each is prepared to
take an adapter to which the pipe fro m the charging cup is connected
when filling. A small side hole at the rear connects the interior of the
rod with the liquid cylinders. When the adapter is not in use, the
opening at the front is closed by a plug.