Thomas SAF-T-LINER C2, Руководство по обслуживанию

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8. Charge the air system to governor cutout, shut
down the engine, and apply the parking brake.
9. Allow pressure to stabilize for one minute.
10. Observe the installed service reservoir gauges.
Pressure should not drop more than 10 psi (69
kPa) within five minutes.
11. If necessary, start the engine and charge the air
system. Shut down the engine and release the
parking brake.
12. Make and hold a full service brake application,
allowing the pressure to stabilize for one minute.
Observe the installed service reservoir gauges.
The pressure should not drop more than 15 psi
(103 kPa) in five minutes.
13. With the air system at full pressure and the en-
gine idling, operate the parking brake control
valve and note that all spring brake chambers
apply and release the parking brake promptly as
the control valve knob is pulled out and pushed
in.
14. Build air system pressure to cutout, then shut
down the engine.
15. Completely drain the secondary (front axle) res-
ervoir. On vehicles equipped with single check
valves, where the air dryer is not attached to the
reservoir, the primary reservoir should not lose
pressure.
16. Make a service brake application. The rear axle
brakes should apply and release, and brake
lights should illuminate.
17. Close the drain cocks, recharge the system, and
completely drain the primary reservoir. On ve-
hicles equipped with single check valves, where
the air dryer is not attached to the reservoir, the
secondary reservoir should not lose air pressure.
18. Start the engine and charge the air system until
the governor cuts out.
19. Shut down the engine and leave the parking
brake released.
20. Completely drain the primary reservoir.
21. Make a modulated service brake application.
Both front and rear brakes should modulate. At a
steady full brake application, pressure should not
drop more than 10 psi (69 kPa) within five min-
utes.
22. Drain all reservoirs, then remove the gauges
from the service reservoirs. Close the reservoir
drain cocks.
23. Remove the chocks from the tires.
42–10 ABS Tone Rings
Cleaning
IMPORTANT: An accumulation of road salt, dirt,
and debris on the antilock braking system (ABS)
tone rings and sensors can cause the ABS
warning light to illuminate.
During winter months in areas where corrosive mate-
rials are used on the highways, periodically clean the
underside of the vehicle to ensure proper ABS func-
tioning. Thoroughly clean the wheel/ABS sensor/tone
ring areas, removing all corrosive materials.
42–11 Bendix Hydro-Max®
Brake System Inspecting
1. Check the fluid level in the hydraulic brake reser-
voir. If needed, fill the reservoir up to the bottom
of the fill-neck. See
Fig. 7 . Use only heavy-duty
brake fluid, DOT 3.
IMPORTANT: Due to the mounting angle of the
hydraulic brake reservoir on some vehicles, it is
not possible to fill the back reservoir up to the
bottom of the fill-neck. For these vehicles, fill
only the front hydraulic brake reservoir up to the
bottom of the fill-neck. See
Fig. 8 for an ex-
ample of the alternate mounting angle.
2. Check all hydraulic lines and fittings for damage,
leakage, or looseness.
Replace damaged or leaking components, and
tighten loose fittings.
3. Check the brake module for leaks. If leaks are
found, repair or replace the brake module. See
Group 42 of the Saf-T-Liner C2 School Bus
Workshop Manual for replacement instructions,
or take the vehicle to an authorized Freightliner
dealer.
4. Check the electrical connections and harnesses.
Make sure the connectors are fully seated and
the harnesses are not chafed or cut. Repair or
Brakes
42
Saf-T-Liner C2 School Bus Maintenance Manual, November 2020
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