Shaft coupling saves fish

A major challenge faced recently by ABSSAC was to develop a flexible shaft coupling that could be used in the drive assembly of an ‘Aerator’ used in the oxygenation of water in fish spawning ponds and small lakes.

Aeration is especially required in times of hot weather where the oxygen concentration within the water can fall and have a detrimental effect on spawning. 

The old connection procedure involved a fast-rotating agitating propeller, placed below the surface of the water, while simultaneously compressed air was piped to just behind the rotating propeller to allow a mix and aeration to take place.

“Although this original process did work, it was not very efficient as the air hose would often move from the optimum position, requiring constant maintenance and monitoring during operation,” says ABSSAC. “In the original design, the immersed propeller was driven via shafting and a series of ‘cardan style’ u-joints, which also required an environmentally-friendly lubrication.”

Hollow centre proves big advantage

However, it was quickly realised that the drive solution offered by ABSSAC could also aid in the quest to improve aeration. The Helical beam coupling by design has a hollow centre and this proved to be a big advantage to the application. The final design of stainless-steel shaft coupling could not only handle the angular offset and torque required, but cleverly would allow a compressed air tube to be fed through the middle, so that oxygen could directly be fed to the middle of the agitating propeller. The end results increased aeration rate by 30%. 

Moreover, the single piece U-joint design also supported the propeller shaft at the motor end, eliminating the need for a bearing. Additionally, the one-piece stainless-steel design did not need lubrication or suffer from oxidation.

“With ABSSAC’s flexible beam coupling product, customers have been able to take their standard coupling designs to the next level,” adds the company, “by incorporating features into the original shaft coupling design. By simply allowing the development of innovative connection solutions from the standard helical beam shaft coupling design, has opened up a plethora of opportunities to the design engineer.”

Potential revealed

The hidden potential of expanding how a shaft coupling physically connects within an application, which is often left to standard grub screw or locking clamp, can enhance the overall efficiency of an application.

In many cases, the final shaft coupling design is normally an amalgamation of separate parts that include such items as external gears, splines, threads and tangs. However, most importantly, it enables the design engineer to achieve far greater usage from one item in the total machine, which inevitably leads to greater efficiency.