Freightliner Business Class M2. Manual - part 26

42–10 Brake Pedal Linkage and

Mounting Plate
Inspection

Inspect the pedal, pedal linkage, and mounting plate
assembly for proper operation, to ensure that any
problems believed to be valve-related are not actu-
ally mechanism issues.

42–11 Air Brake Inspecting and

Leak Test

IMPORTANT: If any of the tests in the following
procedure fail, refer to Group 42 of the
Business Class® M2 Workshop Manual to test
individual air brake components and valves.

WARNING

Some steps in this operation require the parking
brakes to be released. Make sure the vehicle is on
a level surface and all tires are chocked. Failure to
do so could result in the vehicle rolling, causing
personal injury and/or vehicle damage.

With the vehicle parked on a level surface, shut
down the engine, apply the parking brakes, and
chock all tires.

Completely drain all air reservoirs.

Install accurate test gauges in the primary and
secondary reservoirs.

Start the engine and run it at a fast idle.

Record reservoir pressures when the low-
pressure warning turns off.

Record governor cut-out pressure and air dryer
purge pressure.

Reduce service air pressure by applying and re-
leasing the service brakes several times, and
record governor cut-in pressure.

Charge the air system to governor cut-out, shut
down the engine, and apply the parking brakes.

Allow pressure to stabilize for one minute.

10. Observe the installed service reservoir gauges.

The 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 brakes.

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, perform the following:

• On trucks, operate the parking brake con-

trol valve and note that the parking brakes
apply and release promptly as the control
valve knob is pulled out and pushed in on
the spring brake axles only.

• On tractors, operate the trailer supply con-

trol valve knob. Note the air coming out of
the trailer control coupling. Operate the
park control knob and note that the parking
brakes apply and release promptly as the
knob is pulled out and pushed in. Block the
trailer supply coupling, and push the trailer
supply control valve and park control valve
knobs in. When the park control valve knob
is pulled out, the trailer supply knob should
also come out.

14. Build air system pressure to cut-out and shut

down the engine.

15. Completely drain the secondary (front axle) res-

ervoir. On vehicles equipped with a Dryer Reser-
voir Module (DRM) or AD-IS with the air dryer
attached to the reservoir, the primary (rear axle)
reservoir pressure should not drop below 65 psi
(448 kPa). 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 the brake
lights should illuminate.

On tractors, with the trailer supply knob pushed
in, the trailer control coupling should deliver air
during the brake application.

17. Push the trailer air supply valve knob in. With the

secondary reservoir still completely drained,
slowly drain the primary reservoir and record the

Brakes

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pressure at which the knob automatically comes
out. This pressure should be 20 to 45 psi (138 to
310 kPa).

18. Close the drain cocks, recharge the system, and

completely drain the primary reservoir. On ve-
hicles equipped with a DRM or AD-IS with the air
dryer attached to the reservoir, the secondary
reservoir pressure should not drop below 65 psi
(448 kPa). On vehicles equipped with single
check valves, where the air dryer is not attached
to the reservoir, the secondary reservoir should
not lose air pressure.

19. On tractors only:

19.1

Start the engine and build the system air
pressure to governor cut-out.

19.2

Shut down the engine and leave the park-
ing brakes released.

19.3

Completely drain the primary reservoir.

19.4

Make a modulated service brake applica-
tion by depressing the brake pedal. The
front brakes should apply and release
and the brake lights should illuminate. In
addition to the front brakes, with the
trailer supply knob pushed in, the trailer
control coupling should deliver air during
the brake application.

20. On trucks only:

20.1

Start the engine and charge the air sys-
tem until governor cut-out.

20.2

Shut down the engine and leave the park-
ing brakes released.

20.3

Completely drain the primary reservoir.

20.4

Make a modulated service brake applica-
tion. Both front and rear brakes should
modulate. At a steady full brake applica-
tion, the pressure should not drop more
than 10 psi (69 kPa) within five minutes.

21. Drain all reservoirs and remove the gauges from

the service reservoirs. Close the reservoir drain
cocks.

22. Remove the chocks from the tires.

42–12 Bendix E-6 Foot Control

Valve Inspection and
Lubrication

Remove the brake valve from the vehicle; see
Group 42, of the vehicle Workshop Manual.

Remove the roll pin from the brake pedal pivot
pin. See

Fig. 9

Remove the brake pedal pivot pin.

Remove the brake pedal.

Check the brake pedal mounting plate adapter
for signs of wear or cracks at the bosses (the
area from which the pivot pin was removed). Re-
place it if necessary.

Check the brake pedal rollers for signs of wear
or cracks. Replace the rollers as needed.

If the rollers are replaced, replace the roller pin,
install a new cotter pin, bend it to 90 degrees
and apply Torque Seal (OPG F900 White) to the
cotter pin.

Remove the plunger from the valve. Using alco-
hol, clean the existing grease from the plunger.

09/10/2004

f430405

E-6 Foot Control Valve

Mounting Plate

Nut and Washer

Pivot Pin

Roll Pin

Roller

Roller Pin

Pedal

Fig. 9, Brake Pedal and Valve Assembly

Brakes

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Check the plunger for signs of wear or cracks.
Replace it if necessary.

Lubricate the plunger with barium grease (BW
246671).

10. Insert the plunger in the valve.

11. Install the brake pedal with the pivot pin.

12. Install a new roll pin and apply Torque Seal

(OPG F900 White) to the roll pin.

13. Install the brake valve assembly; see Group 42,

of the vehicle Workshop Manual.

14. Test the brakes before returning the vehicle to

service.

42–13 Brake Inspection

Parking Brake Operational Check

IMPORTANT: This procedure should be per-
formed prior to lubrication of the brake compo-
nents.

CAUTION

Perform the following check in a clear safe area. If
the parking brakes fail to hold the vehicle, per-
sonal injury or property damage may result.

With the engine running, and air pressure at cut-
out pressure, set the parking brake.

Put the vehicle in the lowest gear and gently at-
tempt to move it forward. The vehicle should not
move. If the vehicle moves, the parking brakes
are not operating correctly and must be repaired
before the vehicle is returned to service. See
Group 42 of the vehicle Workshop Manual for
repair procedures.

Brake Component Inspection

Park the vehicle on a level surface, set the park-
ing brake, and chock the tires. Once the tires are
chocked, release the parking brake.

WARNING

Manually adjusting an automatic slack adjuster to
bring the pushrod stroke within legal limits is
likely masking a mechanical problem. Adjustment
is not repairing. Before adjusting an automatic
slack adjuster, troubleshoot the foundation brake
system and inspect it for worn or damaged com-
ponents. Improperly maintaining the vehicle brak-
ing system may lead to brake failure, resulting in
property damage, personal injury, or death.

With the engine off, and 100 psi (689 kPa) of air
tank pressure, have an assistant apply and hold
an 80 to 90 psi (550 to 620 kPa) brake applica-
tion.

Check to see if the colored over-stroke band on
each brake chamber pushrod is exposed.

If a band shows, the stroke is too long. Check
the foundation brake components for wear or
damage, and repair as needed. See Group 42 of
the vehicle Workshop Manual for inspection and
repair procedures.

Measure the applied chamber stroke.

See

Table 1

for the proper stroke for the type of

chamber being used. If the stroke is too short,
the brakes may drag or will not fully apply. Check
for improper operation or adjustment of the auto-
matic slack adjuster. See Group 42 of the ve-
hicle Workshop Manual.

Brakes

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Brake Chamber Stroke Specifications

Chamber

Max Applied Stroke: inch (mm)

Manufacturer

Type

Size

†

Gunite

Standard Stroke

1-3/8 (35)

1-3/4 (44)

2 (51)

‡

2-1/4 (57)

Long Stroke

2 (51)

24 (2-1/2 inch rated

stroke)

24 (3 inch rated

stroke)

2-1/2 (64)

Haldex

Standard Stroke

1-3/8 (35)

1-3/4 (44)

2-1/2-Inch Extended Stroke

2 (51)

3-Inch Extended Stroke

2-1/2 (64)

Standard Stroke

2 (51)

Long Stroke

2-1/2 (64)

Meritor

Standard Stroke

Less than 1-1/2 (38)

Less than 1-3/4 (44)

Less than 1-7/8 (48)

Long Stroke

Less than 2 (51)

Standard Stroke

Brakes

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