COLLET AS 8R4520 - Caterpillar

Illustration 1 g00806185
(1) Top piston ring Shape of top piston ring ... Barrel face Width of groove for top piston ring ... 2.06 to 2.08 mm (0.081 to 0.082 inch) Thickness of top piston ring ... 1.97 to 1.99 mm (0.077 to 0.078 inch) Clearance of top piston ring in groove ... 0.07 to 0.11 mm (0.003 to 0.004 inch) Piston ring end gap ... 0.20 to 0.48 mm (0.0079 to 0.0189 inch)Note: Install the word "TOP" toward the top of the piston. New top rings have a red identification mark which must be on the left of the ring gap when the top piston ring is installed on an upright piston. (2) Intermediate piston ring Shape of intermediate piston ring ... Taper face Width of groove in piston for intermediate piston ring ... 2.06 to 2.08 mm (0.081 to 0.082 inch) Thickness of intermediate piston ring ... 1.97 to 1.99 mm (0.077 to 0.078 inch) Clearance between groove and intermediate piston ring ... 0.07 to 0.11 mm (0.003 to 0.004 inch) Piston ring end gap ... 0.30 to 0.63 mm (0.012 to 0.025 inch)Note: Install the word "TOP" toward the top of the piston. New intermediate rings have a green identification mark which must be on the left of the ring gap when the intermediate piston ring is installed on an upright piston. (3) Oil control ring Shape of oil control ring ... Coil spring Width of groove in piston for oil control ring ... 4.04 to 4.06 mm (0.159 to 0.160 inch) Thickness of oil control ring ... 3.97 to 3.99 mm (0.156 to 0.157 inch) Clearance between groove and oil control ring ... 0.05 to 0.09 mm (0.002 to 0.004 inch) Piston ring end gap ... 0.20 to 0.48 mm (0.008 to 0.019 inch)Note: Install the word "TOP" toward the top of the piston. A pin is used in order to hold both ends of the spring of the oil control ring in position. The ends of the spring of the oil control ring must be 180 degrees opposite the end gap of the oil control ring. (4) Diameter of new piston pin ... 29.995 to 30.000 mm (1.1810 to 1.8110 inch)Bore in the piston for the piston pin ... 30.003 to 30.009 mm (1.1812 to 1.1814 inch)Piston height above cylinder block (not shown) ... 0.386 to 0.511 mm (0.0152 to 0.0201 inch)Markings on the Piston
Illustration 2 g00462285
Crown of the piston (1) The arrow, which is marked on the top of the piston crown, must be toward the front of the engine. (2) Height grade Pistons have one height grade. This height grade is marked "Std" on the crown of the piston. The crown of the piston must not be machined in order to obtain the correct piston height.Note: Ensure that the piston ring end gaps of all the piston rings have 120 degrees spacing from each other.