Where there is movement, there is power. A coupling takes that power and transmits it from one shaft to another, which may sound simple enough in theory.
A kid pedalling a bike turns the bike shafts, which takes the power to the chain. In a bike it’s a chain. In a car it’s a drive shaft. But what about on a slurry pump at a mine site? This is where CBC’s expert on Power Transmission, Troy Markland, comes in.
“Slurry pumps have two shafts, one for driving and the other being driven. The power comes from the motor and transfers to the turning shaft through a coupling arrangement,” explains Troy. “Joining two aligning shafts is very difficult to do without any deflection and misalignment.”
For this application, Troy recommends the Fenner FenaFlexTM Tyre Coupling for high flexibility, which he explains is critical on mining applications.
“Fenner® power transmission products have a long history in the mining sector,” says Troy. “From a coupling perspective, Fenner® is widely used by major pump companies, particular on high-speed applications.”
According to Troy, this is due to their premium manufacturing facilities, installation services and highly involved after-market support.
“Fenner® couplings are a robust choice for major pump applications for above ground and below ground operations because they have very good horsepower and misalignment capability,” he explains. “The coupling has up to a 4-degree misalignment which is very good for accommodating the gap between shafts.”
To check that the flanges are parallel with the shafts, CBC technicians take various measurements to ensure the gap between the shafts allows for end-float.
“Since the Fenner® couplings can accommodate a high degree of misalignment, this makes it easier to test for torquing ability, says Troy. “Sometimes we use a laser alignment tool or an alignment shim to check that the installation is parallel to the unit on all sides.”
The couplings have a donut-style hub between two flanges that create flexibility for shaft-to-shaft misalignment.
“The first-rated rubber tyre on the couplings has good vibration dampening properties,” Troy expounds. “Vibrations can cause cracks and fractures on drive equipment and machine failures, so the Fenner® coupling does a very good job at softening the vibration through absorption.”
CBC acquired Fenner® in 2011 and has since continued to work with their engineers and technicians to provide premium couplings to the mining and quarrying segment.
Always refer to the manual for each product for torque ratings.
- Firstly, all mating surfaces of the assembly taper balls and flanges, and taper lock bush bores should be cleaned to remove any debris that might impede assembly.
- Before placing the flanges on to the shaft, loosely place the bush into the taper lock bore and align the half holes correctly.
- Remove clamping rings and screws.
- Place loose clamping rings onto the mover and drive machine shaft before locating coupling flanges.
- If keys are required, side fitting keys with top clearance should be used.
- Once the clamping rings and flanges are in place, tighten the fixing screws to the required torque, detailed in the instructions supplied with each bush.
- For keywayed flanges, place on the shaft, locate keyway, and tighten screws.
- Bring the shafts into alignment, taking into consideration end-float and misalignment.
- Measure the gap between the shaft to the appropriate distance.
- Lay a straight edge across the flanges in several areas to check that they are aligned parallel to one another.
- Open the tyre and place over the coupling flanges ensuring it is seated properly, closing the gap of the tyre.
- Replace the clamping rings over the flanges and tighten the clamping ring screws evenly until the correct screw torque is achieved.
- There should be no metal-to-metal contact between coupling flange and clamping ring.
- Run the coupling under load for a test period, if possible and check the torque to ensure it is correct.