Gear Selection Guide

It has been the greatest dilemma facing the end users in selecting the right and exact gears that matches their expectations, requirements and criteria. It is not an easy task. There may be many parameters that impacts the selection of gears. Unless one is very clear about the nature of job for which the gearing application is applied for, there can be problems that can crop up any time. Highlighted here are some of the basic parameters that go a long way in selecting the right gear.

Choosing Gears based on Gear Strength
This is a most vital step and consists of a thorough comprehension of the following points:

Bending Strength
The permissible bending strength of a gear is referred to the allowable tangential force of the pitch circle. The principle working behind this bending strength is the mutually allowable root stress of two gears meshing under load.

Surface Durability
Surface durability of gears, is actually the allowable tangential force of a pitch circle. It permits a safe force transmission of force without any occurrence of surface failures.

Torque Load
The next step is to make an estimated selection which is based on the torque load. This can be performed with the help of the catalogues, that is made available by the manufactures of different gears.

Calculate the required strength
The gear strength is then calculated based on the actual conditions and using various formulas.


Selection of Gears Based on Application
This method is one of the surest and simple way to make the right choice of gears. The following points should serve as the criteria.

• High Speed Rotation
  Many a Applications needs noise and vibration reduction in the case of high speed gear drives. For this the ground gears are strongly recommended. A good example can be of the Ground Spur Gears.
  
  
• Cost Performance
  It is a known fact that more the production cycles, higher would be the cost. But they even out due to mass production. For example the Injection Molded Gears or Sintered Gears give a good cost-performance figure.
  
  
• Compact Design
  The size of gear is generally proportional to the load capacity. For making the design compact alloys can be used with the help of heat treating.
  
  
• Availability of Secondary Operations
  Please take note of the fact that once the gears are heat treated, the items get hard surfaces. As they gain in strength, but lose out on the ability to perform secondary operations.
  
  
• Backlash Considerations
  For minimizing backlash, it is recommended to use high precision parts that has ability to adjust the center distances.
  
  
• High Reduction Ratios
  Where high reduction ratio is the criteria, the best option would be to have Worm Gear Pair or even high ratio Hypoid Gears. High reduction ratios are also obtained by forming of effective planetary gear systems by applying spur and internal gears.
  
  
• Positioning
  It is advisable to use CP Racks and Pinions for a perfect positioning application. Ground gears can be used in calculating for reducing pitch errors.
  
  
• Prevention of Rust
  Stainless steel and plastics must be used where rust can cause problems, this is important to know in food and chemical processing equipment.