Cleaning, Inspection, and Repair. - TM-55-1925-204-120194

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Figure 4-4. Air receiver (box) removal

TM-55-1925-204-12 TUG Harbor Diesel 1200 H. P. Steel 100 Ft Design 3006 Flight One FSN 1925-375-3003 Manual

Figure 4-5. Air Distributor.

TM 55-1925-204-12

handwheel is at "Ahead" or "Astern", the air start valves return

started by high pressure. air reacting against the piston and

to their open position away from the cam.

cylinder head dome in the proper firing order. Air is admitted to

all cylinders in firing order rotation until the engine begins to

b. Air, Distributor. The marine air start distributor is

fire. The starting mechanism is set into operation by moving

designed for "ahead" or "astern" rotation. It is correctly timed

the control handwheel quickly past asternor-ahead to START.

when the matchmark on the cam is aligned with the center line

This turns the air start control cam into position and moves the

of No. 1 valve, and the No. 1 piston is at top dead center.

air start shutoff valve upward to its open position. High

Number one piston is at top dead center when the chisel mark

pressure air is then admitted to the starting air header and to

on the ratcheting device gear aligns with the crankshaft position

the closed air start check valve in each cylinder head. Air from

pointer. The usual cause of air distributor failure is from leaking

the header also passes to the air start distributor. The

air line bushings or gaskets. Be sure the air reservoirs (tanks)

distributor contains one air valve for each cylinder. Each valve

are drained of moisture, frequently.

is operated by a cam and is normally held open and away from

(1) Cleaning, Inspection, and Repair.

The air

the cam by a spring. High pressure air closes all but three of

distributor requires little attention other than a periodic

the valves. Due to the cam contour, one valve remains open

inspection of the valves for wear, and the line fittings and

and two are partially open. Air then flows through the open

gaskets for leakage. Proceed as follows:

valves to their respective cylinder air start check valves. The

(a) Close the starting air valve.

valves are held in a closed position, and need this secondary air

(b) Remove the bolts and clamps (view A,

to open the valve and permit the primary starting air to enter the

fig. 4-5), and the 7 air lines, as required.

cylinder chamber. After the engine has started, and the control

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