Remove sleeve (22), springs (23 and 24), and check valve (25) from control body (33). Discard springs
and check valve.
Remove o-ring (26) from plug (21) and o-ring (27) from sleeve (22). Discard o-rings.
Remove retaining ring (28) and shuttle valve (29) from control body (33). Discard shuttle valve and
Install new o-rings (30, 31, and 32) on new shuttle valve (29).
Install shuttle valve (29) in control body (33) and secure with retaining ring (28).
Install new o-ring (27) on sleeve (22) and new o-ring (26) on retaining plug (21).
Insert new check valve (25), new springs (24 and 23), and sleeve (22) in control body (33). Secure
components in control body with retaining plug (21).
Install new o-rings (18, 19, and 20) on spools (13).
Install new o-rings (16 and 17) on holders (12).
Insert new springs (15), new seals (14), spools (13), and holders (12) in control body (33). Secure
components in control body with retaining caps (11).
If removed, install connectors (8, 9, and 10, Figure 2-1-13) in control assembly (7).
Position control assembly (7) in dash panel, and secure with screws (6).
Install PARKING BRAKE knob (5) and TRAILER AIR SUPPLY knob (4) on control assembly (7). Tighten
knobs until fully seated, then position so text is upright.
Connect air lines (1, 2, and 3) to connectors (8, 9, and 10).
Close air reservoir drain valves (petcocks).
Operating and Leakage Check
If the park brake control valve does not operate as described, or leakage is
excessive, it is recommended that it be replaced.
Chock the wheels and fully charge the air system.
With the PARK BRAKE control pulled out (exhaust position), coat the exhaust port and plunger stem with a
soap solution. A 1 in. (254 cm) bubble in five seconds is permitted. There should be no leakage between the
upper and lower body.
Push the PARK BRAKE control in (applied position).
A 1 in. (254 cm) bubble in three seconds is
Reduce system air pressure and observe the PARK BRAKE control. It should pop out when the air
pressure drops to approximately 40 psi (275 kPa), exhausting the delivery line and engaging the park brakes.