MWO-9-2320-272-24-1
MODIFICATION OF 5-TON M939 AND M939A1 SERIES TRUCKS
SPRING BRAKE CONTROL VALVE IMPROVEMENT; MODIFICATION WORK ORDER
JULY 1992
MWO-9-2320-272-24-1 - Page 6 of 25
MWO 9-2320-272-24-1
b. Welding and metal drilling equipment necessary to apply MWO are contained in this shop set.
NOMENCLATURE
NSN
FSCM
SUPPLY CATALOGUE
Shop Equipment, Automotive
19204
SC 4910-95-CL-A74
Maintenance and Repair,
Common No. 1
10. MODIFICATION PROCEDURES.
a. Vehicle Preparation. Prepare vehicle for application of MWO by ensuring that vehicle air and
mechanical brake systems operate IAW TM 9-2320-272-10 and TM 9-2320-272-20. Correct any faults found
in brake system before installing this MWO by using the troubleshooting charts and repair procedures in
above cited technical manuals.
WARNING
FAILURE TO DRAIN VEHICLE AIR TANKS COULD RESULT IN INJURY
TO PERSONNEL.
b. Installation of Kit. Spring Brake Valve Guard Kit is installed IAW installation instructions and
drawings included in the kit and provided in Appendix B.
CAUTION
ENSURE AIR LINES ARE NOT TWISTED WHEN INSTALLED.
c. Functional test. Ensure brake system operates properly. Be sure there are no improperly installed
or damaged components of air lines causing a leak or other failure. Conduct this operational test IAW
Preventive Maintenance Checks and Services (PMCS) listed in TM 9-2320-272-10 and
TM 9-2320-272-20. Correct faults before vehicle is returned to service.
11. CALIBRATION REQUIREMENTS.
Not applicable to this MWO.
12. WEIGHT AND BALANCE DATA.
Weight and balance are not significantly affected.
13. QUALITY ASSURANCE REQUIREMENTS.
a. General. The following information is supplied to ensure the proper application of this MWO and to
clarify the installer’s responsibilities for an adequate quality assurance program. The installer’s inspection
methods and procedures shall include, as a minimum, provisions for installer responsibility, Government
verification, in-process inspection, and job inspection. Inspections shall be IAW TM 750-245-45, TM 9-2320-
272-20, TM 9-237, TM 43-0139, and the Spring Brake Valve Guard Kit installation instructions.
b. Installer Responsibilities. Unless otherwise specified in Government contract or purchase order,
installer is responsible to perform all inspection requirements cited or referenced in this MWO. These
requirements must be the basis of installer’s minimum quality assurance (QA) program. Installer’s QA
inspections and tests will comply specifically with all provisions of this MWO pertaining to premodification
inspection, installation instructions, tests, and adjustments, and for notifying the Government
representative of any kits received incomplete or with damaged contents. The installer is responsible for
quality of work for each job in applying this MWO.
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