A I R S Y S T E M A N D B R A K E S
TM 5-3805-258-24-1
T E S T I N G
A N D
A D J U S T I N G
a. If the master cylinder stroke is less than 79.0
mm (3.11 in), see the subject TOO LITTLE
MASTER CYLINDER STROKE.
b. If the master cylinder stroke is at its maxi-
mum, the brake fluid pressure indicator
will come on. See the subject TOO MUCH
MASTER CYLINDER STROKE.
10. Do Steps 1 thru 9 again for the other master
cylinder.
1
GOVERNOR AIR PRESSURES
I
I
950BNS and 950BS
I
Cut-In Pressure
655 i 14 kPe
(95 * 2 psi)
Cutuut Pressure
758 = 14 kPe
(llo*2pai)
I
950BNsai! Uad 950BSCE
I
J
Cut-In Pressure
700+0 -35kPa
(loo+ o-5paii
Cutout pressure
825 *35 kPa
(120 y5psi)
Too Little Master Cylinder Stroke
The steps that follow are probable causes of too
little master cylinder stroke. With each step is a
correction for the problem. Too little master cyl-
inder stroke can be caused by:
1. A failure in the master cylinder.
a.
b.
c.
2. A
Remove and disassemble the master cyl-
inder.
Check for a stuck piston (a piston that will
not move).
Check for a loose locknut on the air cyl-
inder rod.
failure in the head assembly of the wheel
Too Much Master Cylinder Stroke
When the master cylinder stroke is at its maxi-
mum, one pair (front or rear) of wheel brakes will do
all of the work (braking). This condition will cause
hot (overheating) wheel brakes and axle compon-
ents. When this condition exists, the brake fluid pres-
sure indicator will come on.
Too much master cylinder stroke can be caused by:
1. Low brake fluid level in the reservoirs.
a. See the LUBRICATION AND MAINTE-
NANCE GUIDE.
2. Air in the hydraulic circuit.
a. See REMOVE AIR FROM WHEEL
BRAKE HYDRAULIC CIRCUIT (BLEED
THE BRAKES).
3. Leakage in the brake fluid lines.
a. See CHECK FOR LEAKAGE IN HY-
DRAULIC CIRCUIT.
4. Brakes out of adjustment.
5. Failure of the seal on the master cylinder piston.
brake.
a. Remove and disassemble the head assem-
bly.
b. Check for a stuck piston (a piston that will
not move).
4-65
