TM 55-203
CHAPTER 8
CAR BRAKE EQUIPMENT
Section I. CAR TRUCK BRAKE GEAR
and similar equipment either secured directly to the car
8-1.
General
trucks or associated with the car trucks through
component parts of the system. These parts connect
a. Brake gear is the whole combination of parts on
the brakeshoes to the handbrake system and to the
a car or train which, when working together, slow down
piston rod of the brake cylinder of the airbrake system.
or stop the motion of the car or train These parts include
This connection is so made that, when the handbrake
the foundation brake system.
On many oversea
wheel is operated or the air pressure forces the piston
railways, a vacuum brake system is used in lieu of the
out, the brakeshoes are forced against the wheels This
standard airbrake system found in the United States.
action slows down or stops the car or train, depending
upon its speed, the extent of brake application, and the
b. A truck brake assembly includes those parts of
frequency of application. Brake beams, brakeshoes,
the foundation brake gear that are secured directly to
levers, etc., are illustrated in figure 4-29.
the truck. It includes the truck live lever, bottom
connecting rod, bottom brake rod and brake beam
b. Brake Lever Badge Plate
safety supports, truck dead lever, dead-lever fulcrum,
brake beams, brake beam heads, brakeshoes, and all
(1) A standard badge and dimension plate
keys, pins, etc, needed to make the assembly complete
showing the dimensions of the truck and body levers
which are standard for each car was adopted by the
truck live lever with the remainder of the foundation
Association of American Railroads in 1928.
gear.
(2) The badge plate (fig 8-2) is made of metal
c. Foundation brake gear parts, including those
and fastened to the underframe of the car in an
parts known as truck brake gear parts, are standardized
accessible place, preferably near the brake cylinder.
by regulations and specifications Required braking ratios
This plate gives the proper dimensions of the levers for
are fixed by Association of American Railroad (AAR)
both the body and truck brake gear. After an approved
regulations which are strictly adhered to.
These
badge plate has been applied to any car, levers will be
regulations are incorporated in Department of the Army
checked to see that they conform to standard
specifications for all railway equipment for both oversea
dimensions. These requirements are a part of the rules
and domestic service.
in effect on all railroads governing annual repairs to
brakes on freight cars. If wrong levers are found, they
d. Certain railway equipment such as depressed
will be replaced with levers conforming to the
center flatcars and exceptionally long passenger cars,
dimensions shown on the badge plate.
such as circus train cars, because of low congested
center sections on their underframes, require separate
8-3.
Brake Gear Regulators
brake cylinders mounted on each truck for effective
braking action in lieu of the conventional single body-
a. General. Several types of brake gear regulators
mounted brake cylinder and foundation brake gear.
are in use on freight cars. These regulators take up
This difficulty is circumvented by mounting complete
slack manually in the brake gear to adjust piston travel.
and independent brake cylinders with foundation brake
Automatic slack adjusters (fig 8-3) must be properly
gear on each truck.
regulated each time piston travel is adjusted to insure
that sufficient takeup is available to maintain proper
8-2.
Foundation Brake Gear
piston travel en
2) is defined as levers, rods, brakeshoes, brake beams,
8-1
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