We recently visited a water treatment plant in Boca Raton, FL and needed to align an interesting five-machine train. The train consisted of a 1000 HP motor short-coupled to a clutch, water pump, another clutch and diesel engine (see Figure 1):
Fig. 1: 5-Machine Train
The main drive unit is the dark gray motor on the right, which spins clockwise and drives the blue pump in the middle through a clutch (the light gray machine.) The second clutch in the train is to the left of the pump (hidden in the picture above) and is oriented backwards from the first one so as to disengage the yellow diesel engine at the far left from the train when the motor is running. When electric power fails and the motor cannot be used (such as during hurricanes or when an accident disables the electrical grid), the engine is automatically started and spins counterclockwise, driving the pump in the same direction as before through the left hand clutch, whereas the right hand clutch now disengages the motor from the train. It is an ingenious arrangement, designed to keep this critical machine train operational even if one of the drivers were to fail. Some vibration trouble was being experienced and misalignment was suspected.
We brought a ROTALIGN ULTRA IS to the site with four sets of sensALIGN heads. Using the multi-coupling measurement feature in the ROTALIGN (available with the Expert level of the firmware), we were able to take a set of readings across three of the four couplings simultaneously using the Continuous Sweep mode in just minutes. However, since the diesel engine is disengaged from the rest of the train while rotating clockwise from the motor, its shaft does not turn with the rest of the train. This problem was overcome by uncoupling it from its clutch and using a turning gear to rotate the engine shaft separately while utilizing the Pass Mode measurement mode for uncoupled shafts across this coupling.
Although short-coupled with double engagement gear couplings, the fairly large size of each of these couplings meant we could treat them as spacer couplings since the 8-inch span between the ring gears is greater than the minimum 4″ distance between flex planes recommended to consider the coupling as a short coupling.
Fig. 2: Overview of all five machines with sensALIGN components installed
As the diesel engine was manually turned with a turning gear to various positions, the sensALIGN laser on the clutch shaft passed the sensALIGN receiver on the engine shaft several times during the rotation of the train. This way, the entire train alignment could be captured with just one rotation of the shafts:
Engine to Clutch, uncoupled, using Pass Mode Measurement Mode
After the readings were completed, it was time to look at the results. We zoomed the view out to look at the overall alignment of the entire machine train and found this situation in the vertical plane, with the diesel engine on the left set as the reference machine:
As Found Results, Vertical
The results showed that the pump would have be dropped by nearly 20 thousandths at the left pair of feet and nearly 30 thousandths at the right pair of feet. Since it would be very difficult and inconvenient to move this heavily piped pump, we decided to explore alternatives by using the Static Foot function to set the Pump stationary as well. This meant that ROTALIGN would now draw a new optimized centerline through the two stationary machines (the engine and pump) and show us the relative positions of the remaining three machines with respect to this optimized centerline, as shown below:
As Found Results, Optimized through Engine and Pump, Vertical
Since the motor too was large and inconvenient to move, with heavy, inflexible conduit connections, we decided to explore whether alternative shimming solutions existed to achieve a satisfactory alignment by moving only the two clutches in the train. To this end, we now opened the shimming and move simulator in the Rotalign Ultra and discovered that we could in fact achieve an excellent alignment throughout the entire train by moving just the two clutches to get into spec. The left hand clutch (coupled to the engine) could be shimmed up by 10 thousandths at the left pair of feet (closest to the engine) and shimmed up 13 thousandths at the right pair of feet (nearest the pump.) This would achieve an excellent alignment between the clutch and the pump on the right side without compromising the already good alignment between the clutch and the engine on the left side, as illustrated below. Next, we would pivot the right hand clutch (nearest the motor) by raising its left pair of feet (nearest the pump) by 9 thousandths while at the same time lowering its right pair of feet (nearest the motor) by 9 thousandths as well. This would simultaneously achieve an excellent alignment of this clutch to both motor and pump. See below:
Move Simulator, Showing Proposed Shimming Corrections at both Clutches
Leaving the sensALIGN components installed, we were able to monitor the alignment throughout the entire train live as the corrections were made at the two clutches. After the shimming corrections were completed the entire train was remeasured, and was found to be within tolerance, with no further shim changes or horizontal moves required.
The entire alignment of this five-machine train was accomplished in just 4 hours and 37 minutes using the Multicoupling feature for simultaneous measurement across all four couplings, the Continuous Sweep and Pass Measure Modes, the Shimming Simulator and Live Move feature of the ROTALIGN ULTRA IS. Only a tool like the ROTALIGN ULTRA IS could have allowed us to accomplish this complex task with such speed and ease.
The machine owner informed us afterwards that this alignment typically scheduled at least two man-days with traditional methods and was very pleased to get his critical machine train back on line so quickly, saving lots of money in the process.