SPACER COUPLINGS
sPACER COUPLING advantages
What Is A Spacer Coupling?
Spacer couplings consist of shafts mounted with an extra length between the coupling and the pump drive shaft and/or the coupling and the drive, so that bearings and seals can be removed without moving the drive or pump from the foundation.
The coupling interval should be at least 2 inches. Total growth than bearing assembly or seal to be removed. A coupling spacer should usually be specified because it allows the removal of the mechanical seal or removal of the pump without interfering with the alignment of the pump and driver. Industry practice is to specify coupling intervals and leave the pump manufacturer responsible for the correct length.
The advantage of spacer couplings is that it allows for greater actual misalignment between the pump and the drive shaft. Coupling spacers are recommended for all flexible coupling applications.
flexible spacer type coupling
Flexible Spacer Coupling
The flexible spacer coupling is a power drive design that transmits torque and accommodates slight misalignment between the device shafts. They can also handle vibration and shock loads without causing damage to coupled components or equipment.
There are three main types of flexible couplings: disc, diaphragm and metal film. Disc and diaphragm designs gain flexibility by bending thin metal elements or a series of discs, while metal films gain elasticity by coupling the bending of the inner membrane.
Spacer Coupling Catalogue
– Solid and split covers are designed to accommodate higher speeds and increased torque.
– Inherently balanced from precision machining for high-speed applications.
– Design dampens torsional vibration and shock to help extend life of the coupling and surrounding components.
The SXCST Type Close Coupled Split Spacer Coupling is manufactured by Lovejoy, and has two flex planes to accommodate the parallel misalignment by the angular misalignment in each disc pack.
The unit has a split spacer design that allows easy maintenance and replacement of disc pack without moving the equipment.
Fits standard SAE UJ (Universal Joint) companion flanges. Release torque is adjustable by Wedgepin ratings. The maximum release torque is based on maximum Wedgepin capacity and not UJ shaft capacity- Check your UJ shaft manufacturers max load rating.
Spigot diameters may change on higher rated UJ shafts. When selecting high overloads always limit the release torque to 90% of UJ shaft.
The GPL series from AB Transmission are hub-hub couplings designed with integrated rubber elements and a spacer. These devices are suitable for use in different types of application, which require rapid and easy maintenance operations on the coupled machines.
In addition, these tools allows replacement of the rubber elements, and hubs dismounting due to the available spacer.
Hub-hub couplings with rubber elements with spacer, for applications where maintenance operations on the coupled machines are required without moving them.
They have a hub and a bush already machined with bore and keyway. Especially suitable for electric pumps.
Made in steel fully turned with standard treatment of phosphating. Disc pack in stainless steel. High torsional rigidity. Maintenance and wear free. Version with double disc pack: GTR/D. High torque possible.
spacer coupling for pumps
Choosing the Right Pump Spacer Coupling
Choosing the right pump interval coupling is essential to ensure smooth pump operation. Properly designed and maintained septon couplings make it easy to remove mechanical seals and bearings without affecting pump installation and alignment, saving time, money, and long-term hassles.
Coupling Choice:
Rigid couplings connect the pump to the drive shaft and have high tensile strength, which allows them to transfer more horsepower at a given speed than flexible couplings of the same size. However, rigid couplings cannot absorb vibration or thermal expansion and are more sensitive to shaft misalignment than flexible couplings.
Flexibility
Flexible couplings are better suited to compensate for shaft misalignment than rigid couplings because they are able to accommodate motion, such as vibration and thermal expansion, without causing damage to the shaft. However, they are more expensive to manufacture and require lubrication, so choosing the right type for your application is crucial.
Gear Coupling
If radial space is limited, it may be necessary to use a gear coupling to transfer positive torque to the pump. However, because this type of coupling is more sensitive to shaft misalignment, maintenance and lubrication are also more expensive.
Machinery Component Maintenance and Repair
Choosing an Alignment Measurement Setup
Having taken care of the preliminaries, we are now ready to choose an alignment setup, or arrangement of measuring instruments. Many such setups are possible, generally falling into three broad categories: face-and-rim, reverse-indicator, and face-face-distance.
The following sketches show several of the more common setups, numbered arbitrarily for ease of future reference. Note that if measurements are taken with calipers or ID micrometers, it may be necessary to reverse the sign from that which would apply if dial indicators are used.
Figures 5-3 through 5-8 show several common arrangements of indicators, jigs, etc. Other arrangements are also possible. For example, Figures 5-3 and 5-4 can be done with jigs, either with or without breaking the coupling. They can also sometimes be done when no spacer is present, by using right-angle indicator extension tips.
Figures 5-6 and 5-7 can be set up with both extension arms and indicators on the same side, rather than 180° opposite as shown. In such cases, however, a sign reversal will occur in the calculations. Also, we can indicate on back of face, as for connected metal disccouplings. Again, a sign reversal will occur.
In choosing the setup to use, personal preference and custom will naturally influence the decision, but here are some basic guidelines to follow.
This is the setup we prefer for most alignment work. As illustrated in Figure 5-9
1.
Accuracy is not affected by axial movement of shafts in sleeve bearings.
2.
Both shafts turn together, either coupled or with match marks, so coupling eccentricity and surface irregularities do not reduce accuracy of alignment readings.
3.
Face alignment, if desired, can be derived quite easily without direct measurement.
4.
Rim measurements are easy to calibrate for bracket sag. Face sag, by contrast, is considerably more complex to measure.
5.
Geometric accuracy is usually better with reverse-indicator method in process plants, where most couplings have spacers.
6.
With suitable clamp-on jigs, the reverse-indicator method can be used quite easily for measuring without disconnecting the coupling or removing its spacer. This saves time, and for gear couplings, reduces the chance for lubricant contamination.
What is the difference between a spacer vs non-spacer coupling?
Spacer coupling with non-spacer coupling To increase the flexibility of coupling handling large BSE cases, spacers can be added to the coupling design. Also, by utilizing a spacer design with a curved element on each side of the spacer, the coupling can often be expected to handle more misalignments as the spacer components get longer. As a third benefit, the spacer design can also be designed to “exit”, making system maintenance and repair easier.
Whether the coupling is a “spacer” or “non-spacer” design does not describe the type of flexible element incorporated into the design. Elastic couplings (such as Lovejoy spacer coupling’s L-line or S-Flex) and metal couplings (such as gears, grids and discs – as shown above) are both offered as core “non-spacer” designs, but there are also standard and custom spacer varieties.