Test Procedure. - TM-10-3930-634-340189

TM 10-3930-634-34

NOTE

plug out of the body.

Always use new seals when overhauling the

(20) Install a new quad ring seal (42) on the charg-

brake valve.

ing valve spool (43) and install the spool in the body.

(1) Install the filter (52, fig. 5-10) into the valve

Use extra care in installing this spool so as not to dam-

body (3).

age the lands on either the spool or the body. Be sure

(2) Install the steel washer (51).

that the spool is pushed all the way into the body so

(3) Install packing (25).

that the end of the spool contacts the plug in the end of

(4) Install the check valve seat (50), check valve

the valve. At no time is it necessary to force this spool.

(21) Install the charging valve spring (40).

poppet (49), spring (48), and screw plug (46) on which

new packing (47) has been placed into the valve body

(22) Install the stop (41) inside the spring.

(3).

(23) Install new packing (39) on the charging

(5) Torque the screw plug (46) to 35-40 lb-ft.

valve plug (38), and insert it into the valve body. In-

(6) Install the locknut (45) and torque to 35-40 lb-

stall retainer ring (37).

ft.

(24) Install a new "V" block seal (14) on the

(7) Install the ball valve and seat (22) in the valve

plunger (13) with the edge of the seal toward the valve

body with the flange up. Be sure that the seat is prop-

seat (22). Install the plunger.

erly placed in the valve body. Use a wooden dowel to

(25) Install the washer (12).

push this assembly into place.

(26) Install the retaining ring (11) and engage it in

(8) Place the spring (20) on the ball guide (21) and

the groove about the washer,

then the washer (19), packing (18) (with the lip toward

( 2 7 ) Install the packing.

the steel washer) and the teflon backup ring (17).

(28) Install the shims (7 and 8) and spring (9) in

(9) Place new packing (16) on the plug (15) and

the piston (6) and push it into the valve body.

place the assembled parts inside the plug and assemble

(29) Make sure the piston is operating freely, and

to the body.

then slowly release it. Check the clearance under the

(10) Tighten the plug (15) to 35-40 lb-ft.

flange of the piston. If new parts have been used, it

(11) Place new packing (30) on the pilot valve seat

may be necessary to either add or subtract shims (7

(29) and install in the valve body (3).

and 8) from inside the piston (6) in order to g-et the

(12) Push the pilot valve seat into place with a

proper clearance at this point. Proper clearance is

wooden dowel.

from 0.199-0.211 inch.

(13) Install the pilot valve spool (28), the long end

(30) Install the boot (5) and ring (4).

of the spool in the "up" position.

e. Test Procedure.

(14) Place the steel ball (-inch diameter) on its

(1) Before the brake valve is installed in the fork-

seat in the pilot valve insert.

lift, gage test it on work bench to insure that it is prop-

(15) Install new packing (25) on the plug (15).

erly assembled. Brake pressure is the regulated ac-

Place a small amount of grease on the end of the spring

cumulator pressure allowed to pass through the valve

(26) and insert it into the plug. The grease is to hold

to apply the brakes. It is at maximum when the brake

the spring in the plug during assembly.

valve piston is completely depressed. Maximum pres-

(16) Tighten the plug (15) to 30-35 lb-ft.

sure at the valve is controlled by shims assembled be-

(17) Install the spring (34), ball seat (35), and steel

neath the operating piston. Add shims to increase

pressure, remove shims to decrease pressure. Use a

ball (36) (-inch diameter) using grease to hold the ball

and seat to the spring.

0-2,000 pounds-per-square-inch (psi) gage to test the

CAUTION

valve.

Be sure that the steel ball is on the seat be-

(a) Screw gage into brake port on valve.

fore proceeding further.

(b) Fill pump with hydraulic oil, and attach it to

(18) Install the pilot valve adjusting plug (32) on

accumulator port on valve.

which new packing ring (33) has been installed.

(d) Remove boot (5) and depress operating , pis-

(19) Screw the plug (32) down to the dimension

which was recorded at the time of disassembly, and

ton (6) all the way in and read gage. The correct brake

line pressure should read 225-275 psi.

line up the slot in the plug with the mark on the face of

(2) Accumulator pressure is the pressure of the oil

the valve body (3). If new parts have been used to serv-

in the accumulator used for applying the brakes. The

ice the valve at this point, there is a possibility that the

maximum accumulator or high limit pressure is con-

accumulator charging limits have changed. This is

checked when the brake valve is installed on the ve-

trolled by the pilot valve spring. This is purposefully

set below the steering relief valve for safety reasons,

hicle. One full turn of the adjusting plug changes the

high limit by 200 psi. The high limit is raised by screw-

otherwise the components beyond the brake would not

ing the plug into the body and lowered by screwing the

operate. After the brakes have been applied a number

5-17