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W O R TH IN G TO N / proceeding with levelling and the align­ment of the coupling halves. Place a small spirit level on the machined pads of the baseplates and adjust the shims under the bedplate to bring the pump shaft level and pump nozzles into true vertical or horizontal planes. On pumps of the sleeve bearing type the top half bearing caps and bushings may be removed and the unit levelled with the spirit level resting on the shaft. Check as the work proceeds that the gap between the coupling halves at top, sides and bottom is equal and that the peripheries of the coupling halves at each side are in reasonable align­ment. When slight adjustment is neces­sary, this is accomplished either by changing the shims under the baseplate or the shims under the driver feet, making certain that there will remain sufficient space under the driver feet to p e m i t of manipulation of shims when effecting final adjustment of alignment. When this stage of the alignment is com­pleted, tighten the nuts on the holding down bolts moderately and not sufficient to unnecessarily flex the baseplate. The checking of alignment can be accomplished by the use of a, straight edge across the top and sides of the coupling, at the same time checking the faces of the coupling halves for parallel­ism by means of a thickness gauge or set of feelers as shown in Figs. 2 and 3. When the couplings are perfectly true on both the faces and outside di­ameters, exact alignment will show that the distance between the faces is the same at all points and a straight edge will lie squarely across the rims at any point. If the faces are out of parallel the thickness gauge or feelers will show a variation at different points. If one coupling flange is higher than the other the amount may be determined by the straight edge and feelers. It may sometimes be found that the couplings are not perfectly true and not the same diameter. In checking the true­ness of either coupling half, revolve it, holding the other coupling half station­ary and checking alignment at each quar­ter turn of the half being rotated. Next revolve and check alignment of the half previously held stationary. If any vari­ation is found in either of the half couplings, proper allowances must be made in aligning the unit. In cases where pumps are driven by stean turbines which are subject to tem­perature changes in operation, final alignment should be made with the driver heated to its operating temperature. Where this is not possible at the time of alignment, proper allowance should be made. Similarly, where the pump ele­ment is subject to expansion in service due to handling hot liquids, allowance must be provided for this expansion. In 4 W O R TH IN G TO N any case the cold alignment should be checked when hot and adjusted as required before the unit is placed in service. The clearances between the faces of the couplings should be set so that they cannot strike, rub or exert a pull on either the pump or driver. The amount of this.clearance may vary with the size and type of coupling used. With stand­ard designs of motors the best rule to follow is to allow sufficient clearance for unhampered endwise movement of the shafts of the driving element to the limit of its thrust bearing clearance. On motor driven units the magnetic cen­ter of the motor will determine the run­ning position of the motor half coupling. It is well to check this point by oper­ating the motor light before the coup­ling bolts are replaced. If electric power is not available to operate the motor light, move motor shaft in both directions as far as bearings will per­mit then adjust shaft centrally between these limits, assembling the unit with the correct gap between coupling halves. Do not put coupling bolts in until the piping is complete and the driver has been thied out for correct direction of rotation. Important. - Alignment must be check­ed after the pump has been completely piped up for the reason that pumps are easily sprung and pulled out of position by drawing up the bolts in the piping flanges where these flanges are not brought square­ly together before the bolts are tightened. Particular care must be taken to properly support the suction and discharge piping so that they can not exert a strain or pull on the pump. Pipe strains are a common cause of misalignment, hot bear­ings, worn couplings and vibration. GROUTING The bedplate is ordinarily grouted in before the piping connections are made. However, in some special cases, the reverse procedure is permissible. The usual mixture for grouting a machine is composed of one part pure cement and two parts sand with sufficient water to cause the mixture to flow freely under the bedplate. A wooden form should be built around the outside of the bed­plate to contain the grout and provide sufficient head to assure a flow of the mixture underneath the entire bedplate. After grouting, the unit should be al­lowed to set for 48 hours, thereafter the nuts on the foundation bolts Should be firmly tightened. An approved method for finally put­ting the coupling halves in alignment is by the use of a dial test indicator. (1) Move the driver as required, including shimming front or back till the coupling faces are parallel. (2) Bolt the indicator to the pump half of the coupling. With the button resting on the other coupling periphery set the dial to zero and chalk mark the coupling half at the point where the button rests. For any check, top or bottom or sides, rotate both shafts by the same amount, i.e., all readings on the dial must be made with its button on the chalk mark. The dial readings will indicate whether the driver has to be raised or lowered or moved to either side. After any movement, check that the coupling faces remain parallel to one another. EXAMPLE: If the dial reading at the starting point is set to zero and the diametrically opposite reading at the bottom or sides shows a plus or minus .020" the driver has to be raised or low­ered by shimning or moved to one side or the other by half of this reading. NOTE: For all checks including that for parallelism of coupling faces, keep both shafts pressed hard over to one side when taking the readings.