Distrobution agreement signed to support expansion

Power Transmission company Bibby Turboflex South Africa (SA) is expanding and, in May, signed an agreement with local tools and fastener supplier Bolt & Engineering Distributors Group for the distribution of Bibby Turboflex’s full product offering.

Bibby Turboflex SA will exhibit its ‘new and improved’ range at the KwaZulu-Natal Industrial Technology Exhibition, which will be held at the Durban Exhibition Centre from July 23 to 26.

The company manufactures and stocks a range of power transmission equipment for industrial motion control. TB Wood’s Sure-Flex couplings are one such product, offering quick and easy installation and silent operation, and requiring no lubrication or maintenance.

“The Sure-Flex range of couplings is not new to Bibby Turboflex SA’s range. However, the company has embarked on a new sales strategy, which entails tar- getting industries that extensively use these types of couplings, such as the industrial and mining sectors,” says Bibby Turboflex SA sales and marketing manager Kevin Gill.

“The biggest killer of coupling is mis- alignment. Correct alignment is critical for the effective operation of rotating equipment,” says mechanical power transmission products manufacturer Altra Industrial Motion coupling division marketing and business development manager Paul Konkol. Altra Industrial Motion, which is based in the US, owns Bibby Turboflex SA.

“Getting the drive shafts aligned per- fectly when a motor is not running is one matter; however, once the parts start moving, temperatures vary, operating conditions change and foundations settle. Therefore, the correct couplings, in the right size, are needed for the specific application,” he says.

Konkol adds that the basic function of couplings is to transmit power, accom- modate misalignment, compensate for axial movement and to occasionally absorb shocks and vibrations.

The Sure-Flex couplings are used to connect an electric motor to a centrifugal pump, as the elastomeric element compensates for misalignment and allows the absorption of shocks and vibration, which protects connected equipment.

Gill notes that, although no major improvements have been made to the Sure-Flex system, Altra Industrial Motion undertakes continuous research and development programmes to improve the manufacturing of customer-specific offerings.

There are four basic types of shaft misalignment or movement that determine the selection of the correct coupling.

“A parallel misalignment occurs when the two shafts do not share the same rotation axis. Their end faces may be parallel, but their centre axes are laterally displaced with respect to each other,” states Gill.

A second type of misalignment is angular misalignment, which occurs when shafts are neither coaxial nor parallel.

“The angle at which the shafts are misaligned may be symmetrical or asymmetrical,” he points out.

A third type is known as an end float, which occurs when either shaft or both shafts display axial movement by moving in and out of place.

Gill explains that a sleeve-bearing motor floats while the rotor searches for the magnetic centre of the wind. He adds that the temperature varia- tion can also cause thermal expansion, resulting in a positional shift in the shafts.

The fourth type of misalignment is torsional flexibility, which involves torsional movement in planes perpendi- cular to the shaft axis.

Gill explains that shock or vibration causes torsional flexibility, which a torsionally flexible coupling can absorb and dampen.

“The basic construction of the most flexible couplings consists of two flanges or hubs which attach to the shafts being coupled, and a connecting element that may be metallic, or a mechanical connection, such as a gear coupling,” says Gill.

He adds that to be considered flexible, a coupling must handle parallel and angular misalignment.

The elastomeric flexible member can deform or stretch in shear conditions, displacing underload. The amount of torsional displacement or elastomer wind-up is a measure of the shock that can be absorbed. It also compresses easily and stretches to handle end-float.

“The torsional flexibility allows the elastomer shear coupling to dampen the amplitude of vibrations, isolating the transfer of vibration from one shaft to the other. The energy absorbed during shock loads is, essentially, winding up the elastomer in a twisting action,” says Gill.

He adds that since the force of the shock from the motor is reduced by the amount of energy absorbed in the flexible member, the pump shaft is cushioned from the effects of the initial shock.

He explains that the elastomer then unwinds the energy in a controlled manner, transferring a smooth drive to the pump shaft.

However, constant or excessive shock loads, or a sudden locking of the coupling, can cause the elastomer to shear, thus protecting the equipment from damage.

“Couplings that use the elastomeric material in compression do not have the same amount of misalignment capa- bilities as [they have] when operating in shear conditions,” states Konkol.

He says, in compression, the rubber of a coupling is squeezed, rather than twisted, to transmit torque, as the molecular structure of the elastomer material in shear couplings is engineered to withstand shear forces.

Meanwhile, Gill says the company faces the challenge of the influx of cheap imports from Asia.

“Bibby Turboflex SA has had to, as a result of this reality, revisit certain pricing structures and sales strategies, but we regard competition as a good challenge. “We are determined to remain a high-quality product provider that is competitive in all aspects of its business, including pricing,” concludes Gill.