TM 5-3820-246-14&P
5-8. HAMMER PISTON
b. Cleaning/Inspection.
Dry cleaning solvent P-D-680 is TOXIC and flammable. Wear protective goggles and gloves and use in
well ventilated area. Avoid contact with skin, eyes, and clothes, and do not breathe vapors. Do not use
near open flame or excessive heat. The flashpoint 100 140 degrees F (38 60 degrees C). If you become
dizzy while using cleaning solvent, get fresh air immediately and get medical aid. If contact with eyes is
made, wash your eyes with water and get medical aid immediately.
(1) Clean all metal parts with dry cleaning solvent P-D-680 and dry with rag.
(2) Measure small hammer piston rings gap
(position A) and large hammer piston ring
gap (position B) installed in cylinder.
Normal gap is between 0.0098 in. to
0.0177 in. (0.25 mm to 0.45 mm). Replace if
gap is greater than .03937 in. (1.0 mm).
(3) Measure hammer piston diameter at
position A. Normal diameter is between
2.4358 in. to 2.4370 in. (61.87 mm to
61.90 mm). Replace if less than 2.4318 in.
(61.77 mm).
(4) Measure hammer piston diameter at
position B. Normal diameter is between
2.4385 in, to 2.4397 in. (61.94 mm to
61.97 mm). Replace if less than 2.4346 in.
(61.84 mm).
(5) Measure hammer piston diameter at
position C. Normal diameter is between
3.3427 in. to 3.3436 in. (84.906 mm to
84.928 mm). Replace if less than 3.3415 in.
(84.876 mm).
(6) Measure hammer piston diameter at position D. Normal diameter is between 1.2594 in. to 1.2598 in.
(31.989 mm to 32.00 mm). Replace if less than 1.2586 in. (31.97 mm).
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