TM-9-2350-311-20-1
HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5
TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL FOR HULL, POWERPLANT, DRIVE CONTROLS, TRACKS, SUSPENSION, AND ASSOCIATED COMPONENTS
AUGUST 1994
TM-9-2350-311-20-1 - Page 1117 of 1275
TM 9-2350-311-20-1
SECTION I. INTRODUCTION
B-1 GENERAL
This introduction (Section 1) provides a general explanation of all maintenance and repair functions authorized at various
maintenance levels under the standard Army Maintenance System concept. The MAC in Section II designates overall
authority and responsibility for the performance of maintenance functions on the identified end item or component. The
application of the maintenance function to the end item or component will be consistent with the capacities and
capabilities of the designated maintenance levels. Section Ill lists the Special Tools and Test Equipment (both special
tools and common tool sets) required for each maintenance function as referenced from Section Il.
B-2 MAINTENANCE FUNCTIONS
Maintenance functions will be limited to and defined as follows (except for ammunition MAC):
a. Inspect
To determine the serviceability of an item by comparing its physical, mechanical and/or electrical characteristics with
established standards through examination.
b. Test
To verify the serviceability by measuring the mechanical, pneumatic, hydraulic, or electrical characteristics of an item
—
and comparing those characteristics with prescribed standards.
c. Service
Operations required periodically to keep an item in proper operating condition, i.e., to clean (decontaminate), to
preserve, to drain, to paint, or to replenish fuel, lubricants, hydraulic fluids, or gasses.
d. Adjust
To maintain or regulate, within prescribed limits, by bringing into proper or exact position, or by setting the operating
characteristics to specified parameters.
e. Aline
To adjust specified variable elements of an item to bring about optimum or desired performance.
f. Calibrate
To determine and cause corrections to be made or to be adjusted on instruments or test, measuring, and diagnostic
equipment used in precision measurements. Consists of comparisons of two instruments, one of which is a certified
standard of known accuracy, to detect and adjust any discrepancy in the accuracy of the instrument being compared.
g. Remove/Install
To remove and install the same item when required to perform service or other maintenance functions. Install may be
B-2
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