TM 55-203
(b) Apply a few drops of oil to piston
to prevent oil leakage. Make sure the oil plug makes a
bushing and distribute evenly over the entire surface.
seal between the flanged collar and the vearing surface
Evenly distribute one drop of oil on the collar at the
on the piston to prevent oil leakage out of the chamber.
piston spring end of the piston. Then insert the piston
Remove capscrew from oil plug, if used. To tighten oil
and slide valve in the body, ,leaving them in release
plugs of the non-hexagon type, use a torque wrench and
position.
tighten to a force of 17 foot-pounds (200 inch-pounds).
(7) Inspection and lubrication of early type self-
(c) Assemble balance in parts in reverse
oiling piston
order of removal, using new parts as required.
(a) The early vintage type self-oiling piston
has two holes drilled in the piston head near the top of
(11)
Performance of code of tests. Install
the piston. The piston must not be submerged in
reconditioned valve portion on test rack and refer to TM
cleaning fluid. To clean the ring and its groove, squirt
55-21023 for testing instructions.
the cleaning fluid around the ring and then move the
ring around in its groove. Repeat the operation until the
c.
Emergency Portion
ring and groove are thoroughly clean. After cleaning,
(1) Choke fittings.
The emergency portion
blow the excess fluid away with a jet of air.
contains six choke fittings; figure 8-24 illustrates the
(b) If it is necessary to remove the ring
location of these choke fittings. The instructions for
from the piston ((6) above), remove the wick in the
cleaning and checking choke fittings in the service
bottom of the groove. Do not replace when a new ring
portion apply for all of these chokes except for chokes
is applied.
(1'), (3), and (4) which are not readily removable and
(c) Follow the same procedure for filling the
should be cleaned in place. The removable chokes (2),
oil reservoir as described in (6) above.
(5), and (6) must be removed, cleaned, and replaced
(8) Inspection and lubrication of release-insuring
one at a time. Remove the filter felt in choke (5), clean,
and replace or renew if damaged. If choke (5) is the
defects Reseat valve and seat if necessary Test spring
earlier type which does not have a filter felt, replace with
for proper tension using a spring gage Apply new spring
the latest design.
if required.
(a) Choke (3), which serves to protect
(9) Inspection and lubrication of quick-service
against excessive spillover check valve leakage, is
limiting valve and duplex release valve parts
located in the bushing under the spillover ball check (11,
(a) Inspect the quick-service limiting check
valves and release check valves and seats for pitting.
(b) Choke (4) (fig 8-24), which serves to
Renew if found defective. Lubricate the rubber check
protect against diaphragm leakage, is located an the ball
valves by placing them in a box with dry graphite.
check cover in the port between the chamber above the
Shake the box and remove check valves, wipe off
spiliover valves and the chamber above the strut
excess graphite with a chamois.
diaphragm. Orifice size No. 69 drill.
(b) Lubricate the two short prongs of the
(c) Choke (1), which serves to control the
duplex release valve plunger that fit in the bottom of the
rate of quick-action chamber pressure reduction during
reservoir. Release valve body with brake cylinder
an emergency application, is located in the vent piston.
lubricant prior to assembly to the body.
Orifice size No. 69 drill.
(10)
Assembly of parts to service portion
(d) Choke (6), which controls the second
body
stage flow of air to the brake cylinder immediately after
(a) Press the side of the piston ring
the incite valves closes during an emergency
opposite the scarf to the bottom of the ring groove and
application, is located in the emergency portion body
apply three drops of lubricating oil through the ring scarf
and is accessible by removing a 1/4inch pipe plug.
opening. Restore the ring to normal position and
Orifice size 3/32-inch drill.
carefully rotate ring in groove to distribute the oil.
(e) Choke
(5),
which
controls
the
Position the ring scarf approximately 1 inch on either
quickaction chamber charging rate, is located in the
side of the piston top center.
emergency portion body under the ball check cover.
The attached filter felt prevents restriction of the choke
by very fine dirt, thereby insuring the proper charging
rate of the quick-action chamber. Orifice size No. 73
drill.
8-27
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