Heavy Duty Balanced Opposed Compressors - Ariel Corporation

FOR MODELS: JGZ AND JGU SECTION 5 - MAINTENANCE
Checking Connecting Rod (Crank Pin) Bearing Clearances
1. Determine bearing wear by checking actual jack and side clearances against the
clearance limits given in Table 1-4 on Page 1-13 and the last new bearing clearance
check values if available. High copper content in the oil analysis may be an
indication of main and/or connection rod bearing wear, and/or chain idler, crosshead,
connecting rod bushing wear (excessive use of anti-seize lubricants can
also elevate copper content in the oil analysis).
2. Use calibrated dial indicators with 0.0005 inches (0.005 mm) increments and
magnetic stands to check clearances.
3. Before rotating the crankshaft, operate the pre-lube pump to lubricate the bearings.
4. Check jack clearance as follows:
a. Manually rotate the crankshaft to the highest throw position, install a
magnetic stand on the top of adjacent crankshaft web, with a needle type dial
indicator placed against the top of the connecting rod near the cap seam as
shown in Figure 5-2. Set dial indicator to zero.
b. Pull the connecting rod up by using a large bar to pry against the frame on an
eye bolt installed in the rod or use a crane and lifting strap, until needle on
the face of the dial indicator stops moving to check jack clearance. Repeat to
be sure reading is accurate.
Dial Indicator Magnetic Base Placement on Top of
Crankshaft Web, & Showing Eye Bolt and Pry Bar
Using Pry Bar to Check
Jack Clearance
Needle Type Dial Indicator Placement
on Top of Connecting Rod
FIGURE 5-2 MEASURING CONNECTING ROD BEARING VERTICAL JACK
CLEARANCE - TYPICAL
7/09 PAGE 5 - 3