for special equipment to replace the lubricant, Army rail cars with these bearings have been taken care of by
commercial shops.
c. The wedge is a companion piece -to the friction bearing. It is constructed with a rocker contour that
distributes weight evenly over the journal bearing. The wedge receives the proportionate weight of the car and
lading from the journal box and in turn transfers the weight to the bearing; weight is then transferred to the
journal, to the wheels, and to the rails. With heat transfer, the reverse process is true. Heat generated between
the bearing and the journal is transferred through the wedge to the journal box where it is dissipated into the
atmosphere.
d. The packing and lubricant, required with the friction bearing, are housed in the bottom of the journal
box. As the journal turns, it picks up lubricant from the packing which acts as a wick. Lubricant is poured into
the bottom of the journal box in a sufficient quantity to keep the packing saturated. If the lubricant gets low and
the journal becomes dry, a hot journal, called a hotbox, will develop. Prolonged overheating of the journal
causes it to break, resulting in car derailment.
A newer method of journal lubrication has been adopted by most commercial railroads in this country, and
to some extent by the military. Instead of packing separate pieces or rolls of waste beneath the journal, a
special, one-piece lubricator pad is soaked in lubricant for a minimum of 48 hours and then placed beneath the
journal. The Association of American Railroads has approved several different designs and makes of these
pads, but the principle in each is the same. Journal lubricating pads have substantially reduced the number of
hotboxes and the amount of maintenance required when journal boxes are packed in the old way.
e. The journal box lid is hinged at the top of the box and is spring loaded. The lid should remain closed at
all times to prevent any foreign matter from entering the journal box. In a theater of operations, the lid may be
fitted with locking devices to prevent theft of the brass bearing and the waste packing.
3.6. BRAKE RIGGING
The typical freight car has part of the braking apparatus mounted on the truck and part mounted on the car
underframe. This paragraph deals with the brake rigging mounted on the truck only. The remainder of the
apparatus is discussed in a separate chapter.
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