Hydraulic Brake Accumulator Cylinder

TM 10-3930-242-34

Figure 5-10. Brake valve, disassembly and reassembly-Continued.

5-13. Hydraulic Brake Accumulator Cylinder

components beyond the brake would not oper-

ate. After the brakes have been applied a

a. General. The accumulator is provided to

number of times, the pressure decreases to a low

s t o r e energy for a limited number of brake ap-

l i m i t , at which time the accumulator recharges.

plications in case the engine stops running. The

The pressure is the low limit that valve starts to

a c c u m u l a t o r cylinder has a free riding piston.

r e c h a r g e the accumulator. The high limit is the

N i t r o g e n is introduced through a valve on the

a d j u s t a b l e pressure, and once this is set au-

end of the cylinder to charge the cylinder. After

t o m a t i c a l l y , brake valve design determines the

the cylinder has been charged, oil from the hyd-

low limit or cut in pressure to start the recharge

raulic system enters the cylinder at the opposite

c y c l e . The high limit is adjusted by turning the

end, forcing the piston toward the nitrogen,

pilot valve adjusting plug (32). One full turn of

compressing the nitrogen to approximately

the plug changes the limit by 200 psi, turn by

1,300 psi.

100 psi and by 50 psi. The high limit is raised

b. Removal.

by screwing the plug into the body and lowered

by screwing the plug out of the body.

WARNING

(a) Fill pump with hydraulic oil and at-

Bleed the brake system pressure by re-

t a c h it to accumulator port on valve.

peated application of the brakes with the

(b) Pump up valve until a decisive click is

e n g i n e stopped, until the low pressure

heard, caused by shifting of pilot valve, and note

w a r n i n g buzzer sounds. Continue to

gage reading. The reading should be 1,300 psi, if

apply brakes several times to further re-

not, adjust the pilot valve plug (32).

d u c e accumulator pressure. Carefully

(c) After adjusting high limit pressure,

open bleed valves at each automatic slack

let the pressure leak down until another click is

a d j u s t e r to bleed off pressure to the

h e a r d when the low pressure reaches between

wheels. Failure to bleed pressure from

650-550 psi.

b r a k e system before servicing or per-

forming maintenance function may result

( 3 ) While pressure testing valve, check for

in damage to equipment and serious in-

l e a k a g e . Leakage from either the brake port or

jury to personnel. Use only dry nitrogen

r e t u r n port should be less than 60 drops per

gas when servicing the accumulator.

minute. No leakage is permissible from the

pressure port (38). It is not necessary to exceed

Refer to figure 5-11 and remove the hydraulic

1,900 psi for testing pressure as system pressure

b r a k e accumulator cylinder.

is always less.

c. Disassemble, Refer to figure 5-12 and dis-

f. Installation.

a s s e m b l e the hydraulic brake accumulator in

(1) Refer to figure 5-9 and reinstall the

n u m e r i c a l sequence.

b r a k e valve.

d. Cleaning and Inspection.

( 2 ) Install the access panel under the left

(1) Clean the accumulator parts,

fender and install driver's floor plate (TM

( 2 ) Inspect hose for deterioration.

10-3930-242-12).

5-25