Keeping You In The Loop


Debunking the myths around mechanical transmission selections


When making an important decision such as selecting the correct mechanical transmission system, we need to consider the long-term impact that this purchase will have on the company for years to come as these systems generally have relatively long lifespans.

The decision of purchasing a gear unit is often based on what type of unit is currently installed, what the sales representatives are telling you, as well as cost. At Crofts Gears, we know that there is much more to consider in making the correct purchasing decisions.

We’ve put together our top tips for what to consider:

  • Solutions for applications: Selection starts with investigating the input and output power, ratio, speed, space and mounting, running hours per day, and environment.
  • Operating and cost efficiencies: Maintenance, total life cycle cost, initial cost, down time and local support.
  • BBBEE and local manufacturing scorecards: Also consider import and transportation costs.

Clear facts versus generalized untruths:

  • When efficiency is used in sustainability calculations, it is imperative that total running hours per day is used in the calculation as well as nominal (absorbed) power and not peak load as these factors can have a significant impact on calculations. For example, common mistakes are using a bevel helical gear unit (efficiency of about 96%), but coupled with a standard electric motor, where a premium efficiency motor would be far more beneficial.
  • Additionally, it is a very generalized statement to say that worm reduction gear units are inefficient. In fact, efficiency of worm units vary greatly, depending on design and ratio required (95% for low ratio down to as low as 70% on very high ratio).
  • Bevel helical gear units also lose efficiency for every additional stage and each stage has a negative impact on footprint (space and costs), which is often overlooked.

There are many good quality and technologically sound designed gear units available today, however, we should take note that gear units offered from even the top suppliers are not always designed from a technological consideration. Many are designed around enablement of low-cost mass production instead. The unit is still good quality and value for money, but not necessary the best design as anticipated. Each type of gear unit and coupling has both benefits and shortcomings. It is best to consult with specialists who can assist with the selections and even offer alternative solutions.

Application knowledge and engineering expertise, together with manufacturing and service capabilities, ensures that Crofts Gears is your ideal partner – whatever your industry needs. We undertake repairs of all makes and types of industrial gear units, restoring them to the original O.E.M. specifications and standards.

For more information about COVID-19 please visit: COVID-19 Corona Virus South African Resource Portal