CHAPTER 6 R E P A I R OF MAIN HYDRAULIC SYSTEM

TM 10-3930-242-34

CHAPTER 6

R E P A I R OF MAIN HYDRAULIC SYSTEM

Section I. HYDRAULIC CYLINDERS, HYDRAULIC VALVES, HYDRAULIC

RESERVOIR AND HYDRAULIC MANIFOLD

6-3. Dual Overcenter Relief and Replenish-

6 - 1 . General

ing Valve

This section contains information on the

a. Removal.

m a i n t e n a n c e of the hydraulic cylinders, hyd-

r a u l i c valves, hydraulic reservoir, and hydraulic

(1) Remove the console panel located at the

m a n i f o l d that are the responsibility of direct

right side of the driver's seat.

and general support maintenance personnel.

(2) Tag and disconnect tubing and hoses

and cap.

WARNING

(3) Refer to figure 6-2 and remove the dual

R e l i e v e oil pressure by operating con-

o v e r c e n t e r relief and replenishing valve.

t r o l s with engine OFF before opening

lines or connections.

b. Disassembly. Refer to figure 6-3 and disas-

s e m b l e the relief and replenishing valve.

NOTE

c. Cleaning and Inspection.

Tag all hydraulic lines before removal of the lines.

After removal, cap or plug all openings to prevent

(1) Clean all parts thoroughly, using sol-

the entrance of dirt.

v e n t P-D-680, or equal.

( 2 ) Inspect all parts for cracks, breakage,

6-2. Three-Spool Valve

and burrs.

a. Removal. R e m o v e t h e t h r e e - s p o o l v a l v e

( 3 ) Inspect all threads for damage.

(TM 10-3930-242-12).

( 4 ) Replace defective parts.

b. Disassembly. Refer to figure 6-1 and disas-

d. Refer to figure 6-3 and reassemble the dual

s e m b l e the three-spool valve.

o v e r c e n t e r relief and replenishing valve.

e. Installation.

c. Cleaning and Inspection.

(1) Refer to figure 6-2 and install the dual

(1) Clean all parts of the three-spool valve

o v e r c e n t e r relief and replenishing valve.

c a r e f u l l y , using solvent P-D-680, or equal.

(2) Remove any caps and connect the previ-

( 2 ) Inspect the pilot plunger (18, fig. 6-1)

o u s l y tagged hoses and tubing.

a n d the pilot seat (19) for nicks, burrs, and

( 3 ) Install the console panel located at the

scratches.

right side of the driver's seat.

( 3 ) Inspect the spool (27) for scratches and

NOTE

other damage.

(4) Inspect all other parts for distortion,

The dual relief valve is preset at 2100 to 2400 psi.

scratches, burrs and other damage.

The overcenter relief valve is preset at 3000 psi.

( 5 ) Replace all defective parts.

6-4. Two-Spool Valve

d. Reassembly. Refer to figure 6-1 and reas-

a. Removal. Remove the two-spool valve (TM

s e m b l e the three-spool valve.

10-3930-242-12).

e. Installation. Install the three-spool valve

b . Disassembly. Refer to figure 6-4 and disas-

TM 10-3930-242-12).

s e m b l e the two-spool valve.

c. Cleaning and Inspection.

NOTE

(1) Clean all parts of the two-spool valve

Check the pressure at the hydraulic pump. The

c a r e f u l l y , using solvent P-D-680, or equal.

correct pressure is 2000-2100 psi. Adjust the pres-

(2) Inspect the plunger (6, fig. 6-4) and the

s u r e setting at the valve to obtain the correct

pilot seat (7) for nicks, burrs, and scratches.

reading at the hydraulic pump, as necessary.

6-1