Posted on

C3.3B Tier 4 Interim and EU Stage 3A Engines for Caterpillar Built Machines – Crankshaft

Side Clearance of Crankshaft


Illustration 1g03002456

  1. Set a dial indicator with its tip on the end of the crankshaft.

  1. Measure the side clearance by moving the crankshaft to the front and rear.

    Table 1
    Side clearance of crankshaft     New     0.15 to 0.35 mm (0.0059 to 0.013 inch)    
    Allowable limit 0.50 mm (0.020 inch)    

  1. If the measurement exceeds the allowable limit, replace the thrust bearings.

  1. If the same size bearing is out of specifications because of the crankshaft journal wear, replace it with an oversize one.

Oversize Dimensions of the Crankshaft Journal


Illustration 2g03002625

Table 2
Oversize     0.20 mm (0.0079 inch)     0.40 mm (0.016 inch)    
Dimension A     C2.6 - 37.50 to 37.70 mm (1.476379 to 1.4842 inch)
C3.3B - 41.10 to 42.10 mm (1.619 to 1.657 inch)    		 C2.6 - 37.60 to 37.80 mm ( 1.48031 to 1.48819 inch)
C3.3B - 41.20 to 42.20 mm (1.622 to 1.661 inch)    
Dimension B     C2.6 - 26.20 to 26.25 mm (1.03149 to 1.03346 inch)
C3.3B - 28.20 to 28.25 mm (1.111 to 1.112 inch)    		 C2.6 - 26.40 to 26.45 mm (1.03937 to 1.04134 inch)
C3.3B - 28.40 to 28.45 mm (1.119 to 1.120 inch)    
Dimension C     2.8 to 3.2 mm radius (0.11 to 0.12 inch radius)    
The crankshaft journal must be fine-finished to higher than (0.8S).    

Crankshaft Alignment


Illustration 3g03002696

  1. Support the crankshaft with V block on the surface plate and set a dial indicator with its tip on the intermediate journal at right angle.

  1. Rotate the crankshaft on the V block and get the misalignment (half of the measurement value).

    Table 3
    Crankshaft alignment     Allowable limit     0.02 mm (0.0008 inch)    

  1. If the misalignment exceeds the allowable limit, replace the crankshaft.

Oil Clearance between Crankpin and Crankpin Bearing


Illustration 4g03002756

(1) Plastigage

  1. Clean the crankpin and crankpin bearing.

  1. Put a strip of plastigage on the center of the crankpin.

  1. Install the connecting rod cap and tighten the connecting rod bolts to the specified torque, and remove the cap again.

  1. Measure the amount of the flattening with the scale, and get the oil clearance.

    Table 4
    Crankpin outside diameter     New     C2.6 - 46.980 to 46.991 mm (1.84960 to 1.85004 inch)
    C3.3B - 49.980 to 49.991 mm (1.9678 to 1.9681 inch)    

    Table 5
    Oil clearance between crankpin and crankpin bearing     New     C2.6 - 0.011 to 0.058 mm (0.00043 to 0.00228 inch)
    C3.3B - 0.017 to 0.048 mm (0.00067 to 0.0018 inch)    
    Allowable limit 0.20 mm (0.0079 inch)    

  1. If the oil clearance exceeds the allowable limit, replace the crankpin bearing.

  1. If the same size bearing is useless because of the crankpin wear, replace it with an undersize one

    Note: Never insert the plastigage into the crankpin oil hole.

    Note: Be sure not to move the crankshaft while the connecting rod bolts are tightened.

Undersize Dimensions of Crankpin


Illustration 5g03002839

Table 6
Undersize     0.20 mm (0.0079 inch)     0.40 mm (0.016 inch)    
Dimension A     3.3 to 3.7 mm radius (0.13 to 0.14 inch radius)     3.3 to 3.7 mm radius (0.13 to 0.14 inch radius)    
Dimension B     1.0 to 1.5 mm relief (0.040 to 0.059 inch relief)     1.0 to 1.5 mm relief (0.040 to 0.059 inch relief)    
Dimension C     C2.6 - 46.780 to 46.791 mm diameter (1.84173 to 1.84216 inch diameter)
C3.3B - 49.780 to 49.791 mm diameter (1.9599 to 1.9602 inch diameter)    		 C2.6 - 46.580 to 46.591 mm diameter (1.83385 to 1.83429 inch diameter)
C3.3B - 49.580 to 49.591 mm diameter (1.9520 to 1.9524 inch diameter)    
The crankpin must be fine-finished to higher than (0.8S).    

Oil Clearance between Crankshaft Journal and Crankshaft Bearing

  1. Clean the crankshaft journal and crankshaft bearing.

    Illustration 6g03002858

  1. Put a strip of Plastigauge gauge on the center of the journal.

    Note: Never insert the Plastigauge into the oil hole of the journal.

  1. Install the crankcase 2 and tighten the crankcase 2 mounting bolts to the specified torque, and remove the crankcase 2 again.

  1. Measure the amount of the flattening with the scale and get the oil clearance.

    Table 7
    Oil clearance between crankshaft journal and crankshaft bearing     New     C2.6 - 0.030 to 0.051 mm (0.00118 to 0.00201 inch)
    C3.3B - 0.030 to 0.073 mm (0.0012 to 0.0028 inch)    
    Allowable limit 0.20 mm (0.0079 inch)    

    Table 8
    Crankshaft journal outside diameter     New     C2.6 - 72.977 to 72.990 mm (2.87310 to 2.87362 inch)
    C3.3B - 79.977 to 79.990 mm (3.149 to 3.150 inch)    

  1. If the clearance exceeds the allowable limit, replace the crankshaft bearing.

Undersize Dimensions of the Crankshaft Journal


Illustration 7g03009416

Table 9
Undersize     0.20 mm (0.0079 inch)     0.40 mm (0.016 inch)    
Dimension A     2.8 to 3.2 mm radius (0.11 to 0.12 inch) radius     2.8 to 3.2 mm radius (0.11 to 0.12 inch) radius    
Dimension B     1.0 to 1.5 mm relief (0.040 to 0.059 inch) relief     1.0 to 1.5 mm relief (0.040 to 0.059 inch) relief    
Dimension C     C2.6 - 72.777 to 72.790 mm diameter (2.86523 to 2.86574 inch) diameter
C3.3B - 79.777 to 79.790 mm diameter (3.1409 to 3.1413 inch) diameter    		 C2.6 - 72.577 to 75.590 mm diameter. (2.85736 to 2.97598 inch) diameter.
C3.3B - 79.577 to 79.590 mm diameter. (3.1330 to 3.1334 inch) diameter.    
The crankshaft journal must be fine-finished to higher than (0.8S)
Holes to be de-burred and edges rounded with 1.0 to 1.5 mm (0.040 to 0.059 in.) relief.    

Published by John

Leave a Reply

Your email address will not be published. Required fields are marked *