c. Brake piston rod travel.
On conventional two-axle, four wheel
trucks, the brake cylinder is usually attached to the car underframe. The
brake piston rod extends from the brake cylinder and is attached to the
brake lever through a system of rods and levers; the cylinder and the piston
rod are shown in figure 3.7.
Between full brake application and complete
brake release, the piston should travel only 7 to 9 inches.
A railway car with a depressed center or any other obstruction in the
center has its brake cylinders mounted on the trucks. Figure 3.8 shows a
truck-mounted brake cylinder.
The tolerance for the truck-mounted brake
piston rod travel is the same as that for the one mounted on the underframe-
-7 to 9 inches.
3.11. JOURNAL BOX
The journal box is a part of the truck assembly that requires careful
and frequent inspection and maintenance. Failure to lubricate a journal box
assembly properly could cause serious accidents and unnecessary delays and
expense in train operation.
The following subparagraphs discuss the
preventive maintenance checks on the journal box assembly with friction
a. Waste grabs and scratches on the journal. The journal is a highly
finished, rolled-and-ground end to the axle. If loose threads or lint from
the packing, called waste grabs, get wedged between the journal and bearing,
they scratch the surface of the