Driver shaft alignment

Pump shaft and driver shaft alignment is very important for long useful equipment life, and to extend the running time between repairs. Besides, good alignment reduees the progressive degradation of the pump. 

Common practice is to position, level, and secure the driven unit at the required elevation prior to adjusting the driver to align with it. Set the driven unit s shaft centerline slightly higher than the driver. 

Overhung rotors present an easier alignment problem beeause shaft-end alignment is neeessary only at the eoupling between the eompressor and driver. 

Gearboxes must be installed on a rigid base that prevents flexing of its housing and the input and output shafts. Both the input and output shaft must be properly aligned, within 0.002 inch, to their respective mating shafts. Both shafts should be free of any induced axial forces that may be generated by the driver or driven units. 

Belt-drive fault frequencies are the frequencies of the driver, the driven unit, and the belt. In particular, frequencies at 1X the respective shaft speeds indicate faults with the balance, concentricity, and alignment of the sheaves. The belt frequency and its harmonics indicate problems with the belt. Table 44.1 summarizes the symptoms and causes of belt-drive failures, as well as corrective actions. 

The pre-installation equipment inspection should include the following stuffing box space, lateral or axial shaft movement (end play), radial shaft movement (whip or deflection), shaft runout (bent shaft), stuffing box face squareness, stuffing box bore concentricity, driver alignment, and pipe strain. 

Sprocket alignment should be verified by placing a straightedge along the side face of both the driver and driven sprockets. The straightedge should fully contact the faces of both sprockets. If a gap is observed on either face, re-align the shafts. 

---