Freightliner FLA/FLB/FLC/FLD/FLL. Manual - part 31

4.6

Repeat this step to be certain that the
control arm is fully released. Final operat-
ing travel is obtained after the vehicle has
been driven and the brakes are heated.

NOTE: Brake shoe clearance can be in-
creased for inspection or brake system ser-
vicing by turning the manual adjusting nut
counterclockwise (see arrow B in

Fig. 4

Turning it in that direction takes considerable
effort and may be accompanied by a ratch-
eting sound.

Meritor Automatic Slack Adjuster
Lubricating and Checking

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.

Lubricate the slack adjuster using high-
temperature, waterproof grease, NLGI Grade 1,
such as Texaco Thermotex EP No. 1, Shell Da-
rina No. 1, Marathon 528 heavy-duty, Sunaplex
No. 1 EP, Amdex No. 1 EP, or Philube B No. 1. It
should be smooth-textured, corrosion-resistant
grease, free of fillers and abrasives. Lubricate
the slack adjuster through the grease fitting (

Fig. 5

, Ref. 7) until grease is forced out past the

pressure-relief capscrew (Ref. 5), or past the
gear splines around the inboard snap ring.

Check the boot for cuts, tears, or other damage.
Replace it if necessary.

Gunite Automatic Slack Adjuster
Lubricating and Checking

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.

Lubricate the slack adjuster until grease flows
from the grease relief opening. See

Fig. 6

. For

temperatures to –40°F (–40°C), use Lubriplate
Aero; for temperatures to –20°F (–29°C), use
Texaco Multifak EP–2 or MobilGrease No. 77.

The newest Gunite slack adjusters are produced
without a grease relief. During lubrication with a
grease gun, lubricant is forced through the drilled
worm wheel onto the camshaft. Lubricate the
slack adjuster at the grease fitting until grease
appears on the camshaft.

Inspect the slack adjuster for structural damage.
Replace the slack adjuster if needed.

Inspect the slack adjuster boot for cuts or tears.

If the boot is damaged, replace it as follows (see

Fig. 6

3.1

Remove the two clevis pins.

f420012a

10/20/93

Brake Chamber

Clevis

Actuator Rod

Boot

Pressure-Relief Capscrew, Gasket, Pawl Spring,
and Pawl

Manual Adjusting Nut

Grease Fitting (or Lube Plug)

Fig. 5, Meritor Automatic Slack Adjuster

Brakes

42/5

3.2

Rotate the worm shaft adjusting hexnut
counterclockwise to move the link away
from the clevis. About 45 lbf·ft (60 N·m) is
needed. You will hear a clicking sound.

Remove the old boot from the link.

3.3

Install a new boot on the link, heavy sec-
tion down. Be careful not to damage the
boot.

3.4

Seat the boot so that the bottom of the
boot is in the boot insert, and the top is in
the groove of the link.

3.5

Rotate the adjusting hexnut clockwise
until the 1/4-inch hole in the clevis lines
up with the hole in the link.

Install the 1/4-inch clevis pin and the cot-
ter pin.

3.6

Tap the clevis upward or downward until
the large hole in the slack adjuster lines
up with one in the clevis.

Install the 1/2-inch clevis pin and the cot-
ter pin.

WARNING

Make sure both clevis pins are installed. Failure to
do so will cause the slack adjuster to work incor-
rectly, which could lead to loss of braking control.
This could result in an accident causing personal
injury or property damage.

42–04 Meritor Automatic Slack

Adjuster Lubricating

IMPORTANT: Perform

MOP 42–24

before lubri-

cating the slack adjusters.

Remove the pressure-relief capscrew, pawl
spring, and pawl. See

Fig. 5

Examine the pawl for grease retention and condi-
tion. If the grease is in good condition, install the
pressure-relief capscrew, pawl spring, and pawl;
then tighten the pressure-relief capscrew 15 to
20 lbf·ft (20 to 27 N·m). Lube the slack adjuster
through the grease fitting until lubricant is forced
out through the pressure-relief fitting (or pawl
slot).

If the grease has hardened, or the pawl is dry
and shows extreme wear, remove the slack ad-
juster. Disassemble and clean it. Inspect the in-
ternal parts, install new seals and a new boot
when assembling, then install and lubricate the
slack adjuster. See Group 42 of the

Heavy-Duty

Trucks Service Manual

for instructions.

42–05 Wedge Brake Checking

Check brake shoe lining wear to determine the
proper reline time.

Check the lining-to-drum clearance. Automatic
adjusters are working properly if (for brakes
using two parking brake chambers per wheel)
clearance at the inspection hole is between

f420653a

10/27/93

7/16-Inch Adjusting
Nut

Grease Fitting

Boot

Link

Brake Chamber Piston
Rod

Clevis

1/2-Inch Clevis Pin

1/4-Inch Clevis Pin

Grease Relief
Opening

10. Slack Adjuster Spline

Fig. 6, Gunite Automatic Slack Adjuster

Brakes

42/6

0.010 and 0.060 inch (0.25 and 1.5 mm). If ad-
justers are not working properly, schedule the
vehicle for brake system service. See Group 42
of the

Heavy-Duty Trucks Service Manual

For brakes using one parking brake chamber per
wheel, clearance in excess of 0.035 inch (0.9
mm) may require manual adjustment to obtain
optimum performance, until the vehicle can be
scheduled for service.

The above numbers are established as a guide
(to indicate a range) only, and are not precise.
Specific situations may differ due to individual
component combinations of drums and linings,
etc.

Check service and parking brake air systems by
cycling the respective application valves.

Check the service brake by actuating the treadle
several times. Observe the action to determine if
there is correct actuating system function, and
correct lining-to-drum contact.

Check parking brake operation by actuating the
control valve on the dashboard of the cab.

42–06 Wedge Brake Inspecting

and Lubricating

IMPORTANT: Before inspection, cage all parking
brake units manually or by air pressure. See
Group 42 of the

Heavy-Duty Trucks Service

Manual for instructions. Ensure that the emer-
gency brake airline pressure is exhausted be-
fore removing the line from the brake chamber.

Remove the wheels and brake drums. Refer to
the axle section in the service manual for wheel
and drum removal instructions and brake lining
dust warnings.

Inspect the plunger seals. See

Fig. 7

. If seals

are cut, torn, or otherwise ineffective, disas-
semble and overhaul the brake actuating
components.

Remove the pawl assembly, then remove the
adjusting plunger and seal, to check internal con-
dition. If grease is contaminated or hardened, or
if parts are dry, disassemble and overhaul the
brake actuating components.

NOTE: Highly polished parts do not always re-
quire replacement. Only components that are
scored or show other unusual signs of wear
must be replaced.

Grease the unit using multipurpose chassis
grease, NLGI grade 1, such as Texaco Thermo-
tex EP No. 1, Shell Darina No. 1, Marathon 528
heavy-duty, Sunaplex No. 1 EP, Amdex No. 1 EP,
or Philube B No. 1. Assemble the adjusting
plunger, replace the seal (using an appropriate
seal driver), and assemble the pawl. Then,
manually adjust the brake to specifications.

42–07 Alcohol Evaporator

Checking

Bendix

NOTE: During freezing weather, check the alco-
hol evaporator weekly.

Check that all fittings are tight, and that bubbles are
present in the alcohol when the compressor is com-
pressing. See

Fig. 8

. If the alcohol evaporator is not

operating properly, see the troubleshooting guide in
Group 42 of the

Heavy-Duty Trucks Service Manual

f350020a

10/20/93

Adjusting Plunger

Hollow Capscrew

Gasket

Pawl Spring

Adjusting Pawl

Adjusting Bolt

Plunger Seal

Adjusting Sleeve

Fig. 7, Wedge Brake Adjusting Components

Brakes

42/7

Midland

Maintenance is required during both the freeze sea-
son and the off season to keep the alcohol evapora-
tor in good working order.

Off Season

During the off season, drain the unit of alcohol. At
regular engine service intervals, open the drain cock
to remove moisture from the alcohol evaporator. Be-
fore reactivating the evaporator for the next freeze
season, drain, disassemble, inspect, and steam-
clean the unit of any sludge that may have accumu-
lated. It is advisable to replace any rubber parts
when assembling the alcohol evaporator. Perform
this service just before the freeze season.

Freeze Season Reactivation

Remove the filler cap, and check the cap tet-
raseal.

Remove the capscrews and reservoir from the
cover.

Remove the cover tetraseal.

Drain the air tank, and disconnect the line from
the evaporator outlet. Remove the check-valve
retainer, spring, and disc.

Install the disc, spring, and check-valve retainer,
and connect the line to the evaporator outlet.

Install the cover tetraseal.

Install the reservoir on the cover and tighten the
capscrews.

Fill the reservoir with 40 ounces (1183 mL) of
methyl alcohol, then install the filler cap.

42–08 Bendix Alcohol

Evaporator Cleaning

If a strainer is present, check that it is clear. See

Fig. 8

. Clean or replace the strainer if necessary.

42–09 Bendix Alcohol

Evaporator Gasket
Replacing

Disassemble the evaporator and the check valve (if
so equipped). Clean all parts, and replace all gaskets
and rubber parts.

42–10 Bendix Air Dryer

Checking (AD–2, AD–4,
or AD–9)

Bendix AD–2

Check operation of the heater and thermostat. This
can be done by allowing the end cover assembly to
cool below 50°F (10°C), then placing your hand near
the end cover when the ignition switch is turned on.
The end cover should be warm to the touch within a
few minutes. Warming should cease at about 85°F
(30°C).

Bendix AD–4

Check the operation of the end cover heater-and-
thermostat assembly during cold weather.

With the ignition or engine control on, check for
power at the dryer’s electrical terminal, using a
voltmeter or test light. Check between the electri-
cal terminal and the metal end cover. If there is
no voltage, look for a blown fuse, broken wires,
or corrosion in the vehicle wiring harness.

Turn off the ignition switch and cool the end
cover assembly to below 40°F (4°C).

f420005a

01/06/95

Strainer

Fig. 8, Bendix Alcohol Evaporator (sectional view)

Brakes

42/8

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