Gear Matching. Pattern and compatibility

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Gear Matching. Pattern and compatibility

Postby ChevyEFI » Sat Mar 11, 2017 5:26 pm

Gear Matching. Pattern and compatibility

What I know:
Transmission A and transmission B have the same parallel shaft distances.
The helical gears I desire to use together are for the same ratio, tooth count, and manufacturer and lubricant are the same.

Their mounting to the shaft is done differently, so spline / press fit differ. So does the non-functional length of the gear. I can address all three of those factors. There may be a slight gear working length difference.

If the working lengths are centered to each other, how can I validate the teeth are cut in a way to be compatible with each other? I assume hardness might be checked, but I am thinking more along the lines of the way the teeth are cut.

The OEM is absolutely not going to provide engineering details. But, the units do share enough design similarities, bearings, retainers, and other factors that my question is potentially feasible.

Thanks for insight. I don't think I will find a gear maker locally who will know.

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Joined: Thu Dec 08, 2011 9:03 am

Re: Gear Matching. Pattern and compatibility

Postby autogear » Mon Mar 13, 2017 1:48 pm

This is directly from our Chief Engineer George Sollish:

Given that the two gears we want to mesh are designed to operate at the same distance on parallel centers, at minimum we want the following to be identical or compatable:

(1) Hand of helix. If not straight, one must be right hand, the other left.

(2) Pitch. The ratios of the number of teeth to the theoretical diameter of contact must be identical.

(3) Helix angle. The angles of the teeth to the axis of the supporting shafts must be identical.

(4) Pressure angle. The angles of the tooth flanks at the pitchline must be identical.

There are other items to check, such as root clearance and tip geometry, but this would get you started.

George E Sollish

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