SHAFT ALIGNMENT :

PILGRIM WIRE METHOD -

This method produces fairly accurate results especially in a vibration free situation. A piano wire is stretched over the shafting line as a datum pre-tensioned by weights. For alignment over all the shafting including the crankshaft, it is often necessary to swing connecting rods to get a continuous line. Allowance for wire sag varies witrvwire diameter and tension, an empirical formula is generally used. For a wire of 0.5 mm diameter, tension 200N, an approximate expression is Sag = L 2\29.25 where sag is in mm and L is half length of wire in metre.

A light method is used in calibration. One pole of battery is earthed and the other in series with an indicator lamp is connected to dial indicatortouch stylus. As wire is earthed, the slightest touch of stylus on wire causes indicator lamp to light and the height of the shaft is determined. This method only gives the shaft line for the existing ship condition. It does not give the shaft bearing loads.

Taut wire method (Pilgrims wire)

INDEX ADV ENG                                                                                              NEXT