Main bearings
engine
crankshaft
Ø machining Ø max. wear
— A main journal diameter mm 70.000
− 0.040
− 0.020
69.900
— 1st grinding mm 69.750
− 0.040
− 0.020
69.650
— 2nd grinding mm 69.500
− 0.040
− 0.020
69.400
— max. journal taper allowed mm 0.020 0.050
— max. main journal ovality allowed mm 0.005 0.050
— max. journal boring diameter mm 74
− 0.030
0
— B big end journal diameter mm 63.500
− 0.020
0
63.400
— 1st grinding mm 63.250
− 0.020
0
63.150
— 2nd grinding mm 63.000
− 0.020
0
62.900
— big end journal cilindricity mm 0.020 0.050
— big end journal out-off-roudness mm 0.005 0.050
— C main bearing inside diameter mm 70.000
+ 0.068
+ 0.018
70.130
— 1st undersize mm 69.750
+ 0.068
+ 0.018
69.880
— 2nd undersize mm 69.500
+ 0.068
+ 0.018
69.650
— crankshaft end play mm 0.105÷0.300 0.500
Fig. 9 - Crankshaft and main bearing dimensions.
a crankshaft main journal and big end journal machining.
b crankshaft tail journal machining.
c main bearing inside diameter
12
1
29
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