Figure 9-75. Balance of Turbine Wheel and Shaft
When balance is achieved, remove the turbine wheel and shaft from the machine, and add the thrust
bearing (20, Figure 9-70), thrust collar (19), and impeller (9) to the shaft.
Match-mark the impeller to the shaft, and install the locknut (1). Tighten the locknut in accordance
with Figure 9-77, and reinstall the assembly in the balancing machine (Figure 9-76).
Turn the assembly at 3000 r/min, and balance to a tolerance of 0.0003 ounce-inch (0.216 mg/m). To
achieve balance, use a die grinder and rotary file, and remove metal from the areas indicated in Figure
9-76 as necessary. Smooth and blend the filed areas with crocus cloth, P-C-458.
When balance is achieved, remove the assembly from the machine, and remove the locknut, impeller,
thrust spacer, thrust collar, and thrust bearing.
In addition to the worn parts that would normally be replaced during repair, replace the following parts at
Thrust spacer (1 3).
Thrust collar (19).
Thrust bearing (20).
Replace the center housing (18) if the bearing bore is worn larger than 0.9835 inch (24.981 mm).
Replace the turbine wheel and shaft (10) if the shaft is worn more than 0.6254 inch (1 5.885 mm) at either
Perform all other operations in accordance with step d, above.