TM 55-203
for the presence of dirt, grit, scale, or any foreign matter
(2) To remove a truck bolster of the integral cast
which will cause binding and above average wear. The
frame type illustrated in figure 4-28, the following
center plate and pin should be lubricated with suitable
procedures will apply:
hard grease prior to being replaced under the car. The
center plate should be examined for cracks and broken
journal boxes.
portions. If damage is noted, the center plate and
bolster, if necessary, should be removed as outlined in
(b) Disconnect top brake rod from truck live lever.
b, above, and replaced with a new one. If the center
(c) Jack end of car to a height sufficient to allow
plate is riveted on, it can be replaced singly. Liners or
truck to be rolled from under the car.
shims placed in center plates to adjust coupler height
(d) Place safety trestles under corners of car so
surface of the center plate is not reduced below 1 1/8
that if the jacks fail, the car will not fall.
inches. Such liners shall be of one piece not to exceed
(e) Remove center pin. If it is necessary to roll
1/4 inch thickness. To inspect center plates for cleaning
truck from under car before placing safety trestles, a
and lubrication, the car can be raised by hoists or jacks
pair of long-handled tongs-never bare hands-will be
to a sufficient height to make the center plate visible for
used to remove the center pin.
inspection. Care should be taken not to put the hands or
fingers into the center casting under such
(f) Roll truck from under the car.
circumstances.
(g) Remove all brake rigging, including brake
beams, rods, levers, and safety hangers.
steel plates with flat bearing surfaces which contact
(h) By means of jacks or hoists, raise bolster
similar plates on the body bolster, are fabricated as a
sufficiently to permit removal to journal box wedges.
part of the bolsters. They are designed to steady the car
body and prevent excessive rocking by maintaining
(i) Remove spring plank if used.
intermittent contact with similar members of the body
(j) Lower bolster to a position, which will allow the
bolster. Instead of a flat bearing surface, a combination
side frames to be slipped from ends of bolster
of rollers and rockers may be found on some cars. New
cars specifications require side-bearing clearances to be
adjusted within the limits of 1/8 inch to 1/4 inch per
frames clear of bolster.
bearing, measured at each bearing, with the car on level
(l) Remove bolster.
track and the car body level.
Total side-bearing
clearance at B-end and R and A-end L and A-end and R
(3) To reassemble the truck, lower the bolster into
corners must be the same as the total clearance at B-
place, roll up the wheel sets, put the side frames into
end L and A-end R corners, with a permissible variation
position, and assemble the remainder of the parts in the
of 1/8 inch. By raising the end of the car above the
reverse order of the disassembly, described above.
trucks, the side bearings can be inspected for wear or
Bolster side control wedges (if used) should be
breakage. If repairs or replacement are indicated, the
lubricated after assembly.
truck should be rolled out from under the car to facilitate
the repair. If replacement is necessary, the old side
c. Welding Bolsters. Inspection of bolsters removed
bearing can be burned off and a new one affixed by
from car trucks may reveal loose rivets in the male and
riveting or welding in its original manner. Care will be
female center castings and cracks 'in the body of the
taken to adjust for proper clearances.
bolster. There are no restrictions on the welding of
cracks or fractures in bolsters, but cast-steel bolsters
4-21. Truck Springs
must be removed from the car before welding and
normalized after welding. Pressed or structural steel
a. General. The truck bolster ends, properly fitted
bolsters should be removed from the car truck if major
between the columns of the truck side frame, will rest -
cracks or fractures are detected. Loose rivets in the
on unit clusters of coil springs (fig. 4-28) which, in turn,
center plate will be cut out and replaced.
are set into built-up shouldered spring pockets of the
truck side frame and truck bolster. The makeup of the
d. Center Plate The truck bolster center plate (fig. 4-
spring clusters is dependent upon the loads and spring
28) is a depression into which the center casting riveted
travel dictated by operating conditions.
to the center sill of the car fits. It is held in place by the
weight of the car body, the conformation of the casting,
and a center pin. The center plate should be inspected
4-28
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