Bendix Commercial Vehicle Systems BEPA (FORD) 15X4 CAM BRAKE 5/09 - Manual

1
Bendix ® BEPA (Ford) 15" x 4" Cam Brake
SD-22-3250
FIGURE 1
GENERAL DESCRIPTION
The Bendix ® BEPA (Ford) 15" x 4" cam brake is designed
for use on heavy duty highway vehicles. It is a mechanically
actuated, leading/trailing shoe brake with a fi xed position
cam and anchor.
The brake consists of two fabricated steel shoe assemblies
anchored to a cast iron torque spider and actuated by a
single forged S-cam shaft. Two retaining springs secure
the shoe assemblies to the anchor pin. The twin webs of
each shoe assembly are keyed to the anchor pin on one
end and the cam roller on the other. A single shoe to shoe
return spring is used to maintain constant contact between
the shoe, cam roller and cam.
OPERATION
The Bendix ® cam brake operates in the following manner
during a braking application. The force of the push rod of
the actuator is converted from a linear force to a rotary
torque. This is accomplished by use of the slack adjuster.
This torque is transferred to the cam shaft of the foundation
brake due to the spline of the cam shaft being connected to
the gear of the slack adjuster. On the opposite end of the
cam shaft is the S-cam which when rotated lifts the cam
rollers. This spreads the brake shoe ends apart equally and
pivots the shoes about the anchor pin so the brake lining
comes in contact with the rotating brake drum. The friction
created by the lining pressure against the drum generates
the torque necessary to provide a retarding force to slow
down the vehicle. The energy of the vehicle in motion is
converted to heat at the surface of the drum and lining.
This heat raises the temperature of the drum. The heat is
stored in the drum, and fi nally dissipated to the air.