How to get a starter ring gear made?

[bsheahan]

I need a ring gear for my 1924 Diamond T truck with a Hinkley engine. I have given up on finding one. It has an Autolite starter with a 10 tooth pinion. I have a gear background and reverse engineered the gear tooth geometry. The blank needed is a 17.56 inch OD, 13 1/2 inch mounting ID, and 5/8 thick. It is face mounted with 8 - 3/8 holes on a 14 3/4 bolt circle. It is 126 teeth with a 3.5 module and 30 degree pressure angle.

Is there a supplier out there that would make one for a reasonable price? The only one that got back to me wanted $7000. I can supply the blank if needed. I can also put the teeth on if needed but would prefer to have someone wire edm the form and save me a lot of time cutting one tooth at a time. Is there a heat treater you could recommend?

Any suggestions would be appreciated.

Thanks

Bob

[wjguthrie]

At one time i found a company that had a large stock of ring gears. I couldn't find that company but found Thomas register with 90 company s that do ring gears. Here : https://www.thomasnet.com/products/ring ... 289-1.html


Jim /Ohio

[MochetVelo]

Try Al Suering: https://www.suehring.com/

Phil

[bsheahan]

Yes I already contacted him. No luck.

Thanks

Bob

[bsheahan]

Jim

I see Thomasnet has quite a list of suppliers. I will scan them for other promising suppliers

[Kbillet]

Bob, If you know the number of teeth, the diametrical pitch and pitch diameter and are willing to supply the blank, it should be an easy job. Wire EDM is not the way to go. Gear Hobbing or simply using a indexer with a involute cutter would be an extremely cheaper alternative. If this doesn’t make sense, contact me.
Keith

[bsheahan]

The gear is 126 teeth with a 3.5 module 441 mm pitch diameter and 30 degree pressure angle. I have a supplier for the 4140 blank. The metallurgist at work suggested hardening it to 45-50 RC. We have a supplier for wire EDM gear machining at work for small parts. For small quantities of small parts it is cheaper.

The 30 degree pressure angle is the problem. I have not been able to find a source for an involute cutter with a 30 degree pressure angle. I also have not been able to find a supplier to EDM or hob it. They typically are not interested in a one time customer. Do you have a supplier for the involute cutter or to get it hobbed? Do you have a supplier for the heat treating?

Thanks

Bob

[Kbillet]

Bob, I would question a module gear profile in 1924 for an American truck. That being said, a 30 degree pressure angle would be more related to a spline. I could have your blank with 126 teeth, 3.5 module with a 20 degree PA cut for $275. Shipping extra.Starter ring gears are not precision gears.
Keith

[bsheahan]

Keith

I am puzzled with a metric gear profile also. However my 1919 and 1926 Harley's have metric bearings in the transmission. I found literature for the Hinkley engine stating it used a standard SAE barrel mount starter. Was the SAE gear specification metric back then? The correct starter is an Autolite ML4007. I believe finding one is impossible. It's been years looking. The starter is a 3 1/2 inch barrel mount with a very large OD. An Autolite ML4216 starter fits, has the large OD, and the same unusual design for the brush assembly as the Autolite generator that is on my truck. The ML4216 was used in Case LA tractors in the 1940's. I am basing the gear specifications on the drive gear from that starter. The odd thing is that using a 3.5 module and nominal 35 mm and 441 mm pitch diameters on a 238 mm center distance makes 126 teeth fit the circumference of the 441 mm pitch diameter within a couple thousandths of an inch. The diametral pitch calculations just come out weird so I don't think it is english units. I took multiple over pin measurements with different size pins on the 10 tooth drive pinion. When calculating the over pin measurement using the gear dimensions above and a 30 degree pressure angle, I got a good match to my measurements. I also made a small rack segment and the pinion runs on it nice.

I agree a starter ring gear does not need to be that precise. The teeth are too tall for 20 degree pressure angle. The form would be off quite a bit. I will go through the calculations and measurements again but I don't think that will work.

Thanks for the offer.

Bob