JAC Trucks. Service manual — part 137

Depress the brake pedal about 1/2
of the way at a point 25 to 35 m
(28 to 38 yd) ahead of the target
stopping point.
At a point 5 to 6 m (5.5 to 6.5 yd)
ahead of the target stopping point,
slowly release the pedal (about 1/2
to 1/3 of the initial stroke). After the
vehicle has further approached the
target point, slightly depress the
pedal to bring the vehicle to a
stop. In this manner the vehicle
can be gently stopped without
shock.
Pay attention to the following
points:
荫 Since the service brakes pro鄄
vide powerful braking, there is no
need for depressing the brake

pedal all the way except in an e鄄
mergency.
荫 If the vehicle is stopped with
the initial foot

pressure on the

brake pedal, shock will be pro鄄
duced when the vehicle stops.
Slowly ease foot pressure to mini鄄
mize the shock. If the brake pedal
is fully released, however, all the
air in the brake system will be dis鄄
charged and the vehicle may not
stop at the target point but may
move further ahead.
荫 Do not pump the pedal. Fre鄄
quent pumping will result in tem鄄
porary loss of the air and the vehi鄄
cle will move on. In a congested
traffic, there is danger of bumping
into the rear end of another vehicle

ahead. Try to stop the vehicle by
depressing the pedal once.
荫 On air over hydraulic brake ve鄄
hicles, if the buzzer sounds and
BRAKE pilot lamp lights when the
pedal is depressed, stop the vehi鄄
cle immediately. It is the sign of flu鄄
id leaks or low brake performance
due to excessive brake shoe
clearance. Call the nearest service
shop for inspection and repair.
The brake system is a completely
dual system. Even if fluid leaks oc鄄
cur in one of the circuits, therefore,
the vehicle can be stopped
through use of the other circuit.
Abrupt braking
In the event of an emergency, de鄄
press the brake pedal all the way.

54

STARTING & OPERATING

CAUTION:
Frequent use of abrupt braking
will result in premature wear of
the tires, brake drums, brake
linings and other parts and will
reduce the life of all parts.
Avoid use of abrupt braking ex鄄
cept in an emergency. When
the road surface is wet as in
rainy weather or when there is
ice on the road surface, abrupt
braking can cause hazardous
skidding.

The brakes are applied to all
wheels and the vehicle stops
abruptly. Be careful of strong
shock produced when the vehicle
stops.

TO COUPLE A TRAILER
荫 If the trailer is positively cou鄄
pled, theindicator lamp in the in鄄
strument will light. If the lamp does
not light, check

荫 On a pintle hook equipped vehi鄄
cle, the indicator lamp will light
when the trailer lock switch (If in鄄
stalled) is pushed in.
After the trailer has been coupled,
perform the following step and
check:

1. Couple the service 1 and emer鄄
gency air hoses 2 and open air
service valve 3.

55

NOTE:
The

indicator lamp will light

with the gear shift lever only in
reverse

NOTE:
Do not confuse the hoses when
coupling them.

2. On a pintle hook equipped ve鄄
hicle, pull out the cab control valve
and shut off the supply of air to the
trailer before connecting the ser鄄
vice and emergency air hoses.
Connect the air hoses and open
the air service valve. Then, push
the cab control valve in and supply
air to the trailer.
3. Connect the jumper cable.
Check to ensure that the stop
lamps, tail lamps and turn signal

lamps of the trailer light and flash by
operating the respective switches.
4. Release the parking brakes of
the trailer.
5. Pull the trailer brake lever to鄄
ward you to check that the trailer
brakes apply.
If exhaust air sound is heard when
the lever is returned, the brakes
are performing well.
BEFORE USING THE TRACTOR
COUPLER
Before you use the tractor coupler,
you should always;
荫 Apply grease to each nipple
and operating part sufficiently.
荫 Whenever couple a trailer, ap鄄
ply grease to nipples of base up鄄
per part, rolling shaft and bracket

sufficiently.
荫 After cleaning the used grease
in containing to foreign matter, ap鄄
ply new grease sufficiently.

How to adjust rolling angle

56

STARTING & OPERATING

荫 If the inside diameter of jaw is
worn, adjust it.
荫 Turn the limit dog with a tool
counterclockwise.
荫 Loosen the nut slowly. This will
diminish the inside diameter of jaw
according to moving yoke forward.
荫 If it's inside diameter is 51-51.2
using the Gauge, tighten the limit
dog to adhere the nut perfectly. At
this time, check that the gauge
could be rotated by hand.

荫 Before towing, make sure that
there is no interference between
coupler parts.
荫 Confirm the adherence state of
limit dog and nut, operating state
of secondary lock.
荫 Do not tighten the nut clock
wise greater than primary state ab鄄
solutely.
ADJUSTING BED

By rotating the lever 1, the height
of the bed is controlled.

After adjusting bed

Do the adjusting bed lever as
shown below before driving vehi鄄
cle.
Trailer braked and secured by
chocks. Drawbar adjusted to cou鄄
pling height.

57

CAUTION:
Be sure not to hurt yourself.

CAUTION:
Do not use the trailer brakes to
slow down the vehicle. Avoid
using the trailer brakes for a
long period.

CAUTION:
Be sure no one is standing be鄄
tween tractor and trailer during
the coupling operation

TRAILER LOCK SWITCH (If in鄄
stalled)

The trailer lock switch is located on
the instrument panel. Use this
switch to lock the turntable of the
dolly when the vehicle is to re鄄
verse. When the switch is pushed,

theindicator lamp in the

instru鄄

ment will light.
TRAILER BRAKE LEVER

When the lever is pulled toward
you, trailer brakes will be applied.
Use the brakes when going down
a slope. The more the lever is
pulled toward you, the stronger the
braking power will be come. When
the trailer brakes are performing,
the indicator lamp will light.
荫Even when the trailer brakes are

performing, the service brakes will
normally apply.

TILTING CAB

To tilt the cab, drive the vehicle to
a flat surface and proceed as fol鄄
lows:

58

STARTING & OPERATING

1. Apply the parking brake and
shift the gearshift lever into neutral.
Apply chocks to the wheels and
shut off the engine.
2. If there are articles on the seat,
they could break the windshield
when the cab is tilted.
3. Make sure that the doors are
securely closed.
4. Check to ensure that there is e鄄
nough space around the cab.
More than 1 m wide space is re鄄
quired before and above the cab.
5. Before the cab is brought down,
check to ensure that there are no
waste cloth and other combustible
things left behind in the engine
room.
Manual tilting cab

To raise the cab
1. Remove the hook lever key 于
from the lever 淤.
2. Pull the lever toward you.

3. Hold the grip 盂 of the cab.
While pressing it down, pull the
safety hook 榆.
4. The cab will go up. While press鄄
ing it down to prevent abrupt mo鄄
tion, let it go up slowly.
Push the cab all the way up, and
the cab will be automatically held
in position by the cab stay. Insert
the safety pin虞.

59

NOTE:
Make sure that the lever is
pulled all the way until it touch鄄
es the stopper. If the lever is
not pulled, the hook might not
fit in place when the cab is re鄄
turned.

CAUTION:
For safety's sake, make sure
the safety pin is inserted.

PRECAUTIONS DURING OPER鄄
ATION

We recommend the following
points during operation.
Before driving
荫 Check to ensure that the me鄄
ters, pilot lamps and gauges are
performing well.
荫 Release the parking brake lever
all the way and confirm that the
PARKING BRAKE pilot lamp has
gone out.
荫 When making a start in loaded
condition, shift into the 1 st speed
gear and make slow start. Extend鄄
ed use of the clutch in half -en鄄
gaged position will reduce the life
of the clutch.
荫 If strange sound, vibration, un鄄
smooth acceleration, odor or any鄄
thing wrong is noted, stop the ve鄄

hicle and check all conditions im鄄
mediately.

荫 If the causes cannot be found
out or if the correction is impossi鄄
ble, have the vehicle checked by
the nearest service shop.
荫 If hard steering or inadequate
brake application occurs during
operation, stop and check the vehi鄄
cle immediately.
荫 If a pilot lamplights or the
buzzer sounds , stop the vehicle

60

STARTING & OPERATING

immediately.

The red pilot lamps should be OFF
during

operation. If there is any

red pilot lamp that is ON, it shows
that there is something wrong.
Stop the vehicle and check to lo鄄
cate the cause immediately.
荫 The orange and green pilot
lamps will light when the respec鄄
tive switches are turned on .They
do not indicated trouble.

Oil pressure

If the oil press ure falls below 1.5
kgf/cm

2

(50kPa) while the engine is

idling, the OIL PRESSURE pilot
lamp will light and the buzzer will
sound.
Stop the engine and check for oil
leaks and level at once. If they are
good, the oil system is defective.
Have the oil system checked by an
authorized dealer.
荫 The OIL PRESSURE pilot lamp
also light when the oil filter is
clogged. Be sure to check the
pressure gauge to confirm the oil
pressure.
In severe cold weather the pilot
lamp may continue to light for a
while after starting because of in鄄
creased oil viscosity. Do not oper鄄

61

CAUTION:
Operation of thevehicle with a
red pilot lamp ON can be dan鄄
gerous. Be sure to stop the ve鄄
hicle, find the cause and cor鄄
rect defective points promptly.
The buzzer will be silenced
when the vehicle is stopped
and the parking brake lever
pulled.