b. Journal box. Before repacking a journal box, clean it and examine it for cracks that might
leak oil. Saturate the new packing* in oil at a temperature of not less than 70 F. for at least 48 hours.
When the packing is sufficiently drained, oil should not drip from it but should flow from it when
squeezed. Stored packing must be kept in tight containers so that it won't dry out.
2.8.
AIRBRAKES
Before each trip, check the brakes to insure that air compressors are providing enough air for the
expected service, pressure-regulating devices are working properly, brake valves are working in all
positions, and water has been drained from the airbrake system. Locations of some of the airbrake
valves and gages are shown in figure 2.4. Wear or damage to brake rigging should be corrected
immediately and brake cylinder piston travel should be set in accordance with standard operating
practice. Adjustment is usually necessary when travel exceeds 2 inches for each piston. When levers,
pins, and bushings have worn until brake travel can no longer be taken up by turnbuckle adjustment, the
brake pull rod may be shortened by moving the pin to the second hole in the rod. When it becomes
necessary to move the pin to the third hole, all parts should be replaced. Check the following parts:
piston and non-pressure head assembly, piston lubricator, release spring, strainer, cylinder, and valves.
a. Piston and nonpressure head assembly. Clean the piston and nonpressure head assembly with
a hydrocarbon cleaning fluid unless otherwise specified. If there are any cuts or deep scratches on the
packing cup bearing surface or if it is worn so that it does not hold a proper bearing surface on the
cylinder wall, replace it. When applying the packing cup to the piston, hold one side away from contact
with the piston to allow air to escape from under the packing before snapping the cup into place. This
prevents an air pocket from forming between the packing and the piston head which might cause a bad
fit of the packing on the piston.
b. Piston lubricator. Before replacing or reapplying the packing cup, clean the felt swab of the
piston lubricator by brushing it and relubricate it by soaking the unit in oil. If the swab does not have
full contact with the cylinder, adjust it to provide proper contact.
* Lubrication pads, approved by the Association of American Railroads, are used for packing journal
boxes. They come in sizes 5 x 9, 5 1/2 x 10, 6 x 11, and 6 1/2 x 12 inches.
57
Previous Page
