Machinery's Handbook, 31st Edition
SHAFT ALIGNMENT 2727 amounting to the required thickness. Tighten bolts to their prescribed torque each time after placing shims to avoid any movement when working on the other side of the machine. Never loosen all hold-down bolts at the same time. A maximum of two bolts are allowed to be loosened at a time. Loosening all hold-down bolts will lose the entire alignment. Loosen the bolts from either the left or right side of the machine. Then, raise that side just enough to make the shim change. Raising the machine too high can bend the foot. Once the machine is lifted, remove all shims and add or subtract the number of shims required to make the necessary vertical move. Be very cautious at this point not to get confused among a lot of loose shims. Horizontal Moves: It is preferable to utilize a base plate with jackbolts for horizontal moves. If jack bolts are not available, a small hydraulic jack, pipe clamps, or pony clamps can be used. The most accurate method for measuring the horizontal move is to place dial indicators around the machine at convenient locations, such as at machine feet. The indicators can be located anywhere convenient as long as the dimensions used in the alignment calculations reflect the actual position at which measurements are made. When the indicators are mounted, adjust the dials to zero, and move the unit the distance and direction indicated by the calculations. Once the horizontal move has been completed, a final set of readings should be taken to verify both vertical and horizontal alignment. Safety: Shaft alignment should not be performed when machines are running. Before shaft alignment, all sources of power to the machine should be off and verified. Energy sources must be locked out by electrical controls; steam valves, gas main valve, and fuel oil valve must be shut down before shaft alignment. Rim and Face Alignment Procedure.— Fig. 10 and Fig. 11 show dial indicator arrange mentsforrimandfacealignmentthataretypicalofthoseusedintheremainderofthissection. Fig. 10 illustrates a chain indicator jig, but it could be of any type. The arrangement in Fig. 11 represents an equivalent setup. In each figure, two dial indicators are shown, one for the rim reading and the other for the face reading. Darkened squares, triangles or circles are simply to indicate attachment points.
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Fig. 10. Fig. 11. Starting on page 2731, a number of different indicator arrangements are illustrated in Fig. 1a through Fig. 16a . Each arrangement is associated with a specific equation and a chart that facilitates understanding the dial and face readings and the corresponding tasks of determining where shims need to be added or removed and what horizontal moves are required. To use this system, the mechanic needs to set up the rim and face indicators in the most convenient manner, then turn to the figure of the matching indicator arrangement and use the formulas provided. Example Aligning a Motor with a Pump by the Rim and Face Method: A 10-horsepower (7.5 kW) electric motor needs to be precision aligned to a specific pump. Both the pump and motor are to be mounted on a base that when finished will look similar to Fig. 12. Not shown are the intake and discharge piping, electrical fixtures, and other incidentals including shims under the motor feet.
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