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Program: The Installation of Bevel Gears


Part 2 - Understanding Mounting Distance, Contact Pattern and Backlash

Mounting Distance

The Mounting Distance of a bevel gear is perhaps the most important parameter for proper operation.

Mounting Distance can best be defined as the distance from a locating surface on the back of one gear to the centerline of a mating gear.

The optimum value for the Mounting Distance is established by running the gearset, and adjusting its position to obtain a tooth contact pattern that is consistent with smooth running and optimum load distribution between the mating gear teeth.

Because of dimensional variations between parts, each gear in a set has a unique value for the mounting distance, and in most cases, this value is permanently marked on each gear.

Here we see a graphic representation of the gearbox.

The mounting distance for the gear member is the distance between here and here.

The mounting distance for the pinion member is between here and here. To run properly, these distances must be correct.

In some cases, the mounting distance isn’t easily measured in the gearbox, or the customer needs to change the backlash. This will require verification of the actual contact pattern to ensure the mounting distance is correct.  Checking the contact pattern is addressed in an upcoming section.