Komatsu PC01 – HYDRAULIC EXCAVATOR – Crankcase cover, crankshaft, piston

a. Disassembly/reassembly

– Crankshaft bearing
Oil the circumference of the bearing, and install the bearing with the following special tools.

– Timing gear/governor drive gear
Mark a line on the crankshaft and a timing gear.
Set the commercially available bearing puller plate on the bottom part of the governor drive gear and removes the crankshaft and timing gear using a hydraulic press.
Remove the governor drive gear in the same way.

– Timing gear
Using the old gear for reference, make a mark at the same position on the new gear.
Using a hydraulic press, driver and attachment I.D. (special tools), press the new gear onto the crankshaft.

– Governor drive gear
Use a hydraulic press and the common tools shown below to press in a new governor drive gear.

– Piston

b. Inspection
– Cylinder I.D.
Measure and record the cylinder I.D. at three levels in both the “X” axis (perpendicular to crankshaft) and the “Y” axis (parallel to crankshaft). Take the maximum reading to determine cylinder wear and taper.

– Piston skirt O.D.
Measure and record the piston O.D. at a point 10 mm (0.4 in) from the bottom of the skirt and 90o to the piston pin bore.

– Piston-to-cylinder clearance

– Piston ring width

– Piston ring side clearance

– Piston ring end gap

– Piston pin O.D.

– Connecting rod big end oil clearance
1) Clean all oil from the crankpin and connecting rod big end surfaces.
2) Place a piece of plastigauge on the crankpin, install the connecting rod and cap, and tighten the bolts to the specified torque.
Torque: 12 N•m (1.2 kg-m, 9 ft-lb)

3) Remove the connecting rod and measure the plastigauge.

4) If the clearance exceeds the service limit, replace the connecting rod and recheck the clearance.
Replacement connecting rods are available with standard and undersized bearing surfaces.

– Crankshaft bearing free play
1) Clean the bearing in solvent and dry it.
2) Spin the bearing by hand and check for play.
Replace the bearing if it is noisy or has excessive play.





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