Section III. TECHNICAL PRINCIPLES OF OPERATIONS

TM 10-4930-233-14

TM 4930-14/1

Overall width .......................................................................................................................... 83.5 in.

Shipping weight ..................................................................................................................... 5500 lb.

Shipping cubage ................................................................................................................... 758 cu ft

Center of gravity .......................................................................................................... See data plate

Section III. TECHNICAL PRINCIPLES OF OPERATIONS

1-10. MAJOR ASSEMBLIES

SKID SUB ASSEMBLY

a. The skid sub assembly (1) is a highly mobile self contained unit that is capable of dispensing various types of

COMPRESSOR ASSEMBLY

b. The control panel (2) contains the controls and gages required to operate the compressor assembly. There are

two switches located on the control panel. These switches allow starting and continued operations of the air

compressor assembly. The gages are provided to allow the user to monitor air compressor operations. Panel

lights are provided to aid in night operations.

c. The starter (3) draws power from the batteries in order to crank the engine. These batteries are stored in the

battery box assembly (4) located in the reel cabinet (5). After startup, the belt driven alternator (6) supplies

power for charging.

d. The engine (7) supplies power to turn the air compressor (8) by way of two air compressor drive belts. A system

of pressure and temperature switches protect the engine from operating when oil pressure is low or when

crankcase temperature goes above a preset maximum. These switches automatically ground out the magneto,

stopping the engine.

e. As the compressor (8) turns, it provides air 'o the receiver tank (9). The receiver tank then stores the pressurized

air until it is needed for servicing operations. There are two unloader systems built in to the air compressor. The

first vents starting of the engine. The second receives air flow from the pilot valve and stops air compression

when the air pressure reaches 175 psi. The pilot valve also releases a small amount of air to the air cylinder

mounted on the engine (7). This air cylinder controls the throttle and will decrease engine rpm when pressure

reaches 175 psi. As the engine throttles down, the clutch prevents the compressor drive belts from turning. This

also stops air compression. If the pressure does raise above 200 psi, there is a pressure relief valve that pops

off to vent excess pressure that could cause serious safety problems.

LUBE TANK

f. The compressed air is sent to a separate regulator (10) for each of the low and high pressure pumps (11). This

regulator controls the speed of the pump which affects the force that the lubricant is dispensed with. The low and

high pressure pumps are mounted in the lube tank (12) and deliver the lubricant to the various dispensers. The

lube tank has three compartments which contain engine oil, gear oil and general purpose grease. During cold

weather, the alcohol injector (13) can be used to prevent freezing of the air lines. The dispensers (14) are

mounted at the end of hoses stowed on the reel cabinet assembly (5). The oil (gear and engine) dispensers are

metered to allow control of the amount of lubricant delivered.

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