TM-9-2320-272-24-1
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 1 OF 4
JUNE 1998
TM-9-2320-272-24-1 - Page 968 of 1015
3-213. DOUBLECHECK
TM 9-2320-272-24-1
THIS TASK COVERS:
a. Removal
b. Installation
APPLICABLE
MODELS
REFERENCES (TM)
All except M931/A1/A2 and M932/A1/A2
TM 9-2320-272-10
TOOLS
TM 9-2320-272-24P
General mechanic’s tool kit (Appendix E, Item 1)
EQUIPMENT CONDITION
MATERIALS/PARTS
Parking brake set (TM 9-2320-272-10).
Air reservoirs drained (TM 9-2320-272-10).
Locknut (Appendix D, Item 299)
Antiseize tape (Appendix C, Item 72)
GENERAL SAFETY INSTRUCTIONS
Do not disconnect air lines before draining air
reservoirs.
Do not disconnect air lines before draining air reservoirs. Small
parts under pressure may shoot out with high velocity, causing
injury to personnel.
NOTE
Doublecheck valve No. 2 is located left of the transfer case
parking brakedrum inside left frame rail.
Tag air lines for installation.
1.
Disconnect two wires (6) from stoplight switch (5).
2.
Disconnect treadle valve control line (7) from doublecheck valve No. 2 (3).
3.
Disconnect secondary relay valve control line (9) from elbow (8).
4.
Disconnect doublecheck valve No. 1 output line (10) from elbow (11).
5.
Disconnect primary relay valve control line (13) from valve adapter tee (12).
6.
Remove locknut (2), screw (1), and doublecheck valve No. 2 (3) from left frame rail (4). Discard
locknut (2).
NOTE
If new doublecheck valve is being installed, use fittings from old
check valve.
Wrap all male pipe threads with antiseize tape before
installation.
1.
Position doublecheck valve No. 2 (3) against frame rail (4) and install with screw (1) and new locknut (2).
2.
Connect treadle valve control line (7) to doublecheck valve No. 2 (3).
3.
Connect secondary relay valve control line (9) to elbow (8).
4.
Connect doublecheck valve No. 1 output line (10) to elbow (11).
5.
Connect primary relay valve control line (13) to valve adapter tee (12).
6.
Connect two wires (6) to stoplight switch (5).
3-604
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