Crankshaft - Kubota SM-E4B Series Workshop Manual

SM-E4B SERIES, WSM

(4) Crankshaft

Clearance between Piston Ring and Piston Ring Groove
1. Clean the rings and the ring grooves, and install each ring in its
groove.
2. Measure the clearance between the ring and the groove with a
feeler gauge.
3. If the clearance exceeds the allowable limit, replace the piston
ring.
4. If the clearance still exceeds the allowable limit after replacing
the ring, replace the piston.
Second
ring
Clearance between
piston ring and piston
ring groove
Oil ring
Crankshaft Side Clearance
1. Set a dial indicator with its tip on the end of the crankshaft.
2. Measure the side clearance by moving the crankshaft to the
front and rear.
3. If the measurement exceeds the allowable limit, replace the
thrust bearings.
4. If the same size bearing is useless because of the crankshaft
journal wear, replace it with an oversize one referring to the
table and figure.
Factory specification
Crankshaft side
clearance
Allowable limit
(Reference)
• Oversize thrust bearing
Oversize Bearing
Thrust bearing 1 02
0.20 mm
0.0079 in.
Thrust bearing 2 02
Thrust bearing 1 04
0.40 mm
0.016 in.
Thrust bearing 2 04
• Oversize dimensions of crankshaft journal
Oversize
46.10 to 46.30 mm
Dimension A
1.815 to 1.822 in.
23.40 to 23.45 mm
Dimension B
0.9213 to 0.9232 in.
1.8 to 2.2 mm radius
Dimension C
0.071 to 0.086 in. radius
The crankshaft journal must be fine-finished to higher than Rmax. = 0.8S
1-S61
Factory
0.0900 to 0.120 mm
specifica-
0.00355 to 0.00472 in.
tion
Allowable 0.15 mm
limit 0.0059 in.
Factory
0.040 to 0.080 mm
specifica-
0.0016 to 0.0031 in.
tion
Allowable 0.15 mm
limit 0.0059 in.
9Y1210785ENS0088US0
0.15 to 0.31 mm
0.0059 to 0.012 in.
0.50 mm
0.020 in.
Code Number
15261-23950
15261-23970
15261-23960
15261-23980
0.20 mm 0.40 mm
0.0079 in. 0.016 in.
46.30 to 46.50 mm
1.823 to 1.830 in.
23.80 to 23.85 mm
0.9370 to 0.9389 in.
1.8 to 2.2 mm radius
0.071 to 0.086 in. radius
9Y1210785ENS0089US0
KiSC issued 01, 2013 A
ENGINE
Marking
020 OS
020 OS
040 OS
040 OS