Use of Gear Coupling for better torque transmission

Gears

The Merriam - Webster dictionary defines a gear as One of a set of toothed wheels that work together to alter the relation between the speed of a driving mechanism. In simpler terms, a gear is an engineering component, generally used to transmit torque. Gears are adorned with cut teeth (also called cogs) which mesh with each other generating rotational torque to change the torque, speed and even direction of a power source. Gears are the primary constitution of any machine and their usage can be dated back to A.D 50 in Greece.

Couplings:

Couplings are devices that are utilized in mechanical applications to connect two rotating shafts together. Couplings are seen in a plethora of different forms and serves a wide range of advantages right from transmitting shock load from one shaft to the other to substitute misalignment of the shafts and provide stability.

So what are Gear Couplings?

Gear Couplings are a special type of coupling that features cut tooth for better grip. Just like any other couplings these mechanical aids also are used for torque transmission. Till this day, gear couplings remains to the most preferred method for joining shafts that are not collinear and find usage in almost every industrial arena. The normal ratio of the internal and external gear of this coupling is 1:1, and the to facilitate significant angular displacement between both the gears, the tooth flanks and the outer diameter of the gear on the external side is crowned. The tooth size is considerably large to maintain stability and higher torque density.

When compared with the other forms of coupling Gear Coupling features a long list of advantages, the most prominent ones being fair misalignment capacity, surpassing torsional stiffness and very high torque density. But the sole problem with this mechanical device is its tendency for vibration, when not checked properly. This happens due to the high backlash in the gear teeth, designed to allow for angular misalignment. If such vibrations are not kept in check, this may lead to corrosion of the wear and tear and ultimately damage to the entire equipment or machine.

Gear couplings, although very efficient and reliable demands maintenance and if not maintained properly, it might give away very soon. Right from the time the the device is installed and a few factors regarding its design and specifications must be considered. Moreover, it is very important to select the right gear coupling for the right application.

A few factors that one should always keep in mind while selecting a gear coupling:

• The application torque must be correctly calculated.
• The coupling should always have a torque capacity more than that required.
• The size of the shaft should always be bigger than the size of that of the application.
• The coupling needs to be balance, esp for high speed gear couplings.
• The service factor should be determined.

Apart from these, various factors like proper coupling gap, proper sealing, lubrication, alignment, hub installation, sleeve fits are extremely important for better function of the equipment.