Miter Gears

Miter gears are a very special type of industrial bevel gear that is specifically designed for operating in pairs. The unique Miter Gear has a set of tooth that is identical in number, diametral pitches, and a ratio of 1:1. Miter Gears are perfectly suited for those applications where torque ratings have been precisely calculated. For high efficiency, Miter Gears are put to use as right angle drives. Here motion and power is transmitted between intersecting shafts at right angles.

Generally Miter Gears are cut at 20 degree pressure angle. The long addendum system is applied for compensating the tooth undercut in gears & pinions that has inadequate number of teeth. It must be remembered that Miter Gears that has only identical number of teeth, pitch and pressure angle will function together. However, more than two identical miters can be applied in cases such as differential arrangement.

Installing Miter Gears
For operating with smoothness, without noise and efficiently Miter Gears need to be properly mounted. Listed here are following points that needs to be considered for mounting these Gears.

• Mounting at proper angle : Miter gears for a successful application, and to have a perfect tooth bearing, should be mounted at 90° angle.
  
  
• Mounting Distance (MD) to be specified : Mounting Distance is calculated as the distance from the end point of the hub of a gear to its corresponding mating gear's center line. Gears that are mounted at the specified Mounting distance displays a genuine and proper backlash also the ends of the gear teeth will flush properly with each other. Let's analyse the problems associated with incorrect Mounting Distance.
  
  
  1. Mounting Distance is less than specified dimension : In this case of mounting distance of one or both the gears being less than the specified dimension, the teeth shows a tendency to bind. This also can lead to an excessive wear or even the damaging consequences like breakage can also occur. The following drawing illustrates gears being mounted incorrectly, with a very short Mounting Distance for one gear.
     
     
  2. Mounting Distance is more than the specified dimension : It is also cause for concern in cases where Mounting Distance of any of the gear happens to be longer than the specified dimension. This can also lead to damaging consequences like the gears not on a full mesh on a common pitch line. Also the gears may show excessive backlash. Now this excessive backlash or play, as it is called if not controlled can lead to sudden impulses or shock load while starting or reversing. Eventually causing serious damage to the gear tooth. The following image shows mounting distance which is more than the specified dimensions.
     
     
• Use of Correct Bearings : All Miter gears in transmitting power develop radial and axial thrust loads. This loads must be accommodated by proper use of bearings. Actually the thrust of Miter Gears can lead to gear separation. It is advised to use either ball bearings or roller bearings. It is better to give sleeve bearings a miss. As miter gears are found in cone shape, they generate axial thrust forces. This is particularly distinct with regard to spiral miter gears. In this case the thrust's directions changes with the direction of rotation and the hand of spiral. This is described with the help of the diagrams.
  
  
• Proper Fastening : As the Miter gears generate thrust loads, the gears, shafts as well as the bearing does show a tendency for loosening up while in the operation process. That is the reason why Miter gears should be properly fastened to the shaft. This can be done with taper pins, keys and set screws, step shafts, etc.
  
  
• Correct Tooth Contact : When the Miter gears are assembled in a proper manner, the contact occurs on both gears just in the middle of flank and center of face width, somewhat that is near to the toe. An incorrect tooth contact results in Offset error, Shaft angle error, Mounting Distance error.

Materials for Miter Gears
There are a variety of materials that can be used for the construction for Miter gears. Like Plastic, steel etc. While talking of the manufacturing material Miter Gears can be made by Sintering, Carburizing, Case hardening. Lets have an in depth look at some of the Miter Gears that are made of Steel with their usual specifications. These are plain bore gears with hub. These are some of the examples of specifications and there could be Miter gears with other specifications also.

16 Pitch Steel Miter Gears with Pressure Angle of 20°

10 Pitch Steel Miter Gears with Pressure Angle of 20°

32 Diametral Pitch 0.40 Carbon Steel with 20° Pressure Angle

A Checklist on starting operations of Miter gears Before operating a Miter Gear, the following points need to be checked: Are the Miter gears mounted firmly on the shafts? Is uneven tooth contact eliminated? Is the gear mesh having the require amount of backlash? (Please try to avoid the condition, where there is no backlash) Is the lubrication enough?