pistons - gudgeon pins - piston rings
Pistons
Pistons are specially forged hypereutectic aluminium-silicone-alloy. The
air-fuel mixing chamber machined in piston crown has toroidal shape.
Both the part number and reference A (meaning air) are printed in piston
top, i.e. the piston identification code.
Piston rings
Pay particular attention to the identification marks on the piston rings for
correct assembly.
Inserting the first or the second piston ring upside down will result in either
engine uneven operation or serious damage, even though the piston
groove is the correct one. The figure above illustrates how assembly
should be performed correctly.
Warning - When replacing piston rings in turbocharged engines pay
particular attention that also the second piston ring be provided with
external "CHROMIUM PLATED" sealing surface. (This to avoid installing
improper, not chromium-plated rings belonging to aspirated engines).
Fig. 28 - Measuring piston diameter.
aspirated engine turbocharged engine
Ø machining Ø max. wear Ø machining Ø max. wear
A piston diameter at 90° of the gudgeon pin
axis and at 10 mm from the bottom base mm 104,9
±
0,007 104,680 104,9
±
0,007 104,680
B clearance betwen piston ring and piston
ring gooves in piston (new piston ring)
1st piston ring mm 0,110
÷
0,145 0,250 0,145
÷
0,095 0,250
2st piston ring mm 0.050
÷
0,085 0,150 0,080
÷
0,115 0,200
3st piston ring mm 0,030
÷
0,065 0,150 0,030
÷
0.065 0,150
C piston ring and gap
1st piston ring mm 0,400
÷
0,650 1,500 0,400
÷
0,650 1,500
2st piston ring mm 0,400
÷
0,650 1,500 0,400
÷
0,650 1,500
3st piston ring mm 0,300
÷
0,600 1,500 0,300
÷
0,600 1,500
D inside diameter of gudgeon bore
in piston mm 35
+ 0,012
+ 0,006
35,020 35
+ 0,09
+ 0,03
35,020
E gudgeon pin diameter mm 35
− 0,006
0
34,970 35
− 0,006
0
34,970
Fig. 27 - Piston, piston ring and gudgeon pin dimension.
engine
crankshaft
12
1
35
www.maskinisten.net
www.classicmachinery.net
To Next Page
Loading...