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-   -   Working out what gear to order. (http://www.stationary-engine.net/forum/showthread.php?t=45465)

Dan_pt 14-03-18 08:50 AM

Working out what gear to order.
 
Hi, I need to replace the magneto gear on a Ruston APE as it has two damaged teeth. I have looked on the HPC website and I need to work out the DP of the old gear to order a replacement. Do I measure the distance between the teeth or is there a formula I need to work to or is it a case of the number of teeth Vs the diameter? Sorry if this is a silly question but I don't want to order the wrong one!

Dan.

Headless 14-03-18 09:33 AM

What is the outside dia and number of teeth, from that I can look up the DP and pitch dia.

sinna42 14-03-18 09:34 AM

All you need is the Outside Diameter & the No of Teeth.

OD = (N+2)/P

OD = Outside Diam
N = No of Teeth
P = Diametral Pitch (DP)

For Metric gears

Module = 1/DP
And therefore Module = OD/(N+2)

Hope that helps !
Cheers,
Jim

Dan_pt 14-03-18 10:19 AM

Thank you for the help. I will measure it later on.

Dan.

nickh 14-03-18 10:31 AM

Quote:

Originally Posted by Dan_pt (Post 405570)
Hi, I need to replace the magneto gear on a Ruston APE as it has two damaged teeth. I have looked on the HPC website and I need to work out the DP of the old gear to order a replacement. Do I measure the distance between the teeth or is there a formula I need to work to or is it a case of the number of teeth Vs the diameter? Sorry if this is a silly question but I don't want to order the wrong one!

Dan.

Do HPC still do a paper catalogue? It used to have useful full scale silhouettes of various tooth profiles which was a big help in identifying.

NHH

Dan_pt 14-03-18 10:40 AM

I have no idea Nick. I just looked at their website. The gear I need is under 2" diameter so should be quite reasonably priced. Hopefully all tht will need doing to the new gear is to have a taper machined into it to suit the magneto shaft.

Dan.

martinpaff 14-03-18 11:26 AM

I was also wondering about the paper catalogue, the printed tooth profiles are very useful. Not least because there is another variable; gear teeth also have a pressure angle, and they're not all the same.

I have found the HPC gears are very high quality but tend to be quite thick. There's a fair chance you will also need to slim it down a bit.

MP

Dan_pt 14-03-18 05:59 PM

I have measured my gear and it comes out at between 1.77 and 1.8 inches depending on where I measured it

Using the above formula it comes out at 10 DP. Does that sound right?
It has 16 teeth.

Dan.

Chippie 14-03-18 06:19 PM

Based on your info, HPC gears list one, their G10-16 comes in at 16 teeth and 1.8 in diameter, 21 ish....plus carr

A 10 dp gear cutter in hss is about the same price....if you got a mill and indexer to make your own gears....

Headless 14-03-18 06:20 PM

Looking in the Machinery Handbook it is 10 DP.


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