JAW SECTION OF BACKHOE BUCKET WILL NOT STAY TIGHTLY CLOSED

TM 5-2420-222-20-1

ORGANIZATIONAL TROUBLESHOOTING - CONTINUED

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

14. JAW CYLINDER DOEWS NOT WORK - CONTINUED

e. If manifold-to-jaw control valve oil lines (1) (Serial Numbers 235786 thru 235999 only) have

sharp bends, dents, or kinks, replace (page 2-1456).

Step 2.

Connect hydraulic system test set between jaw control (direct linear) valve (2) and jaw cylinder (3).

Have assistant start and run engine at 1,250 rpm (TM 5-2420-222-10). While assistant operates

short jaw pedal (4), note reading on hydraulic system test set. Pressure gage reading should be

1700 to 1800 psi (11,645 to 12,411 kPa). Shut down engine (TM 5-2420-222-10) and disconnect

hydraulic system test set.

a. If hydraulic system test set pressure gage reads 1700 to 1800 psi (11,645 thru 12,411 kPa),

replace jaw cylinder (page 2-1703).

b. If hydraulic system test set pressure gage reads less than 1700 psi (11,645 kPa), replace jaw

control valve (Serial Numbers 235786 thru 235999 only) (page 2-1242); or jaw direct linear valve

(Serial Numbers 319995 thru 342573 only) (page 2-1250).

15. JAW SECTION OF BACKHOE BUCKET WILL NOT STAY TIGHTLY CLOSED

Step 1.

Check to see if check valve (5) is properly installed. Arrow on check valve (5) must point toward jaw

control (direct linear) valve-to-manifold block rod end oil line bulkhead elbow (6).

a. If check valve (5) is properly installed, go to step 2.

b. If check valve (5) is not properly installed, install as outlined in jaw control (direct linear) valve

tubes and fittings (page 2-1391).

Step 2.

Replace check valve (5) as outlined in jaw control (direct linear) valve tubes and fittings (page 2-

1391).

a. If new check valve (5) corrects problem, get rid of old check valve (5).

b. If new check valve (5) does not correct problem, go to Hydraulic System Malfunction 14: Jaw

Cylinder Does Not Work, step 2, above.

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