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Program: The Installation of Bevel Gears


Interpreting and Correcting Contact Pattern Errors

Profile error occurs when the mounting distance is incorrect. This is the most common type of error and is the easiest to correct.

First, we see the condition where the gear has high toe contact on the convex side and high heel contact on the concave side. Also, the pinion has low heel contact on the convex side and low toe contact on the concave side. To correct this, the mounting distance must be decreased.

In this example, the gear’s convex side has low heel contact and the concave side has low toe contact. As for the pinion, the convex side has high toe contact and the concave side has high heel contact. For this condition the mounting distance must be increased.

For both types of profile error, altering the mounting distance is accomplished through the use of shims.

In this illustration, we can see the location of the shims which are used to alter the mounting distance.

The condition of Cross Contact occurs when the pinion is either too high or too low in relation to the gear.

Here we see the contact patterns when the pinion is too high. The convex side of the gear has heel contact and the concave side has toe contact. Corresponding contact errors are also found on the pinion. To correct this, the pinion would need to be moved down.

If the pinion is too low, the convex side of the gear has toe contact and the concave side has heel contact. Again, corresponding contact errors are also found on the pinion. To correct this error, the pinion would need to be moved up.

Be sure to note that correcting this problem by moving the pinion up or down - is usually not possible without modifications to the gearbox housing.

The third condition is Shaft Angle Error. This is caused by incorrect shaft orientation of the gear and pinion.

Here, on the gear and pinion, we see toe contact on both the convex and concave sides. To correct this error, the shaft angle must be decreased.

On the other hand, if heel contact is present on the convex and concave sides of both gear and pinion, the shaft angle must be increased. However, correcting this problem by moving the shaft angle - also requires modifications to the gearbox housing.