DISC BRAKE ASSEMBLY
1. Head assembly. 2. Anchor pin. 3. Friction pad. 4.
Metal backing. 5. Piston. 6. Disc.
HEAD ASSEMBLY (CALIPER)
1. Anchor retaining bolt. 2. Metal backing. 3. Friction
pad. 4. Anchor pin. 5. Bleed valves. 6. Piston and
seal. 7. Head assembly.
Oil flow to the brakes is through lines and drilled
passages to all pistons within each head assembly.
When an application of the brakes is made, the
hydraulic pressure is made the same (balances) the
pistons and the force on each side of the disc is the
same. The pistons do not have return springs.
To make a pad replacement the caliper need not be
removed. For replacement of pads, remove the anchor
pin and slide the pad out.
Do not make a brake application with pads
removed. The pistons must not be permitted
to extend out of their bores as the pads are
removed. Open the bleed valves on the caliper
to release any pressure on the piston. If the
pistons extend and let the seals come out,
caliper removal will be needed to install the
Two bleed valves on each caliper are used to let air
out of the hydraulic brake system. Let air out of the
brakes (bleed) whenever a line is disconnected in the
hydraulic brake circuit.
Pull on the knob for the parking brake control valve to
open the valve and activate the parking brake. Push on
the knob to release the parking brake. Air pressure in
the line to parking brake control valve must be 50 psi
(345 kPa) minimum for the valve to stay closed. The
parking brake activates automatically when the air
pressure in the line to the parking brake control valve
goes below 40 psi (280 kPa).
PARKING BRAKE CONTROL VALVE