Hydraulic Control Valve, Cleaning, Inspection and Repair

TM 10-3930-630-34

compressed air.

(3) Place the hydraulic control valve on a

b. Inspect mating surfaces of section bodies for

clean work bench.

b. Disassembly.

paint or burring. Remove by light lapping.

c. Inspect valve spools and bores for burs

and scoring. If burs or scoring are present remove with

NOTE

crocus cloth. If scoring is excessive the valve body and

Particular attention should be given

spool must be replaced.

to identification of parts for

d. If springs were removed check for cracks,

reassembly as spools are selectively

wear, deformation or signs of weakness.

fitted to valve bodies and must be

e. Inspect valve sections for cracks, stripped

replaced in their original position.

threads or other damage. Replace all

Valve sections must be reassembled

defective parts as authorized.

in the same order.

3-20.

Hydraulic Control Valve, Reassembly and

(1) Remove four nuts (1, fig. 3-7) and screws

Installation

(2) and separate the valve sections (23 and 39).

a. Reassembly

Remove and discard packings (3 and 4) and seals (5)

NOTE

from between valve sections. Do not lose retainers (6)

Coat all parts with hydraulic oil (OE/

and shims (7).

HDO) to facilitate assembly and

(2) Remove two screws (8) and lift retainer (9)

provide initial lubrication.

from the tilt section.

(1) Install a new packing (45, fig 3-7) on

(3) Remove sleeve (10) from tilt section bore

plug(44) and install plug in lift section (39) of control

and remove packing (11) from the sleeve.

valve. Tighten plug securely but do not overtighten.

(4) Slide spool (12) out of bore and remove

(2) Install a new packing (41) on relief valve

packings (13 and 15) and backup ring (14) from the

plug (40). Place relief valve (43) in bore of lift section,

grooves in the spool. Do not remove the centering

hex nut end up. Install spring (42) and plug (40). Tighten

spring (16) or washers (17) unless replacement is

plug securely, but do not over tighten.

necessary.

(3) Install a new backup ring (36) and packing

(5) Grip the stem of check valve plug (18) with

(35) on the check valve Plug (34) with the packing

a pliers and pull plug from the body of lift section (23).

toward the spring and ball. Place ball (38) and spring

(6) Remove packing (19) and backup ring (20)

(37) in lift section body and install plug (34). Be certain

from plug (18). Remove spring (21) and ball (22) from

the hole in plug (34) lines up with the stud hole in the

the body of tilt section (23).

body of lift section (39).

(7) Remove two screws (24) and remove

(4) If the centering spring (32) was removed,

retainer (25) from lift section (39).

install spring (32) and washers (33) on spool (28).

(8) Remove sleeve (26) from lift section bore

(5) Install new packing (29 and 31) and backup

and remove packing (27) from the sleeve.

ring (30) in the grooves on the spool (28) in the bore of

(9) Slide spool (28) out of the lift section bore

lift section (39).

and remove packings (29 and 31) and backup ring (30).

(6) Install new packing (27) in sleeve (26) and

Do not remove centering spring (32) or washer (33)

install sleeve (26) and retainer (25). Install two screws

unless replacement is necessary.

(24) and tighten securely.

(10) Grip the stem of check valve plug (34) with

(7) Install a new backup ring (20) and packing

a pliers and pull plug from the body of lift section (39).

(19) on check valve plug (18). Packing (19) must be

(11) Remove packing (35) and backup ring (36)

installed towards spring (21).

from plug (34). Remove spring (37) and ball (38) from

(8) Place ball (22) and spring (21) in tilt section

the body of lift section (39).

(23) and install plug (18). Be certain the hole in plug (18)

(12) To remove relief valve in lift section (39),

lines up with the stud hole in the body of tilt section (23).

screw out plug (40) which retains relief valve (43).

(9) If centering spring (16) was removed,

Remove packing (41) from plug and discard packing.

install spring (16) and washers (17) on spool (12).

(13) Remove spring (42) and relief valve (43)

(10) Install packing (13 and 15) and backup ring

from valve lift section.

(14) in the grooves on spool (12). Install spool (12) in

(14) Remove plug (44) and remove and discard

the bore of tilt section (23).

packing (45).

(11) Install new packing (11) on sleeve (10) and

install sleeve (10) and retainer (9). Install two screws (8)

3-19.

Hydraulic

Control

Valve,

Cleaning,

and tighten securely.

Inspection and Repair

a. Clean all metal parts in cleaning

compound, solvent (Fed. Spec. P-D-680). Dry

thoroughly with

3-10