Gear vs Chain efficiency
Gear vs Chain efficiency
(OP)
We are working on a high mileage car with a 1HP engine. Yes, a 1HP engine. We are thinking about cutting a large diameter plastic gear on our CNC that will be driven by our small engine. We have some ideas that we like about this. Our question is, are simple spur gears as efficient as a chain or flat belt drive. Our ration is about 14:1. Any help in this matter would be great.
Thanks
Thanks





RE: Gear vs Chain efficiency
For a practical car drive, you probably need a steel gear with oil lubrication. Due to the high strength of hardened steel, the gear can be quite small and this keeps the size and cost down when comparied to plastic.
The only chain drives, in modern automotive hitory, were the Invo-chain used in some early GM front wheel drives. Didn't stand the test of time.
RE: Gear vs Chain efficiency
Here are some common parameters of transmission choices:
Spur Gearing (steel)
transmission ratio optimum: 2-8
transmission ratio extreme: 20
efficiency: 97-99%
weight/power [kg/kW]: 1.8-0.4
Chain transmission
transmission ratio optimum: 1-6
transmission ratio extreme: 10
efficiency: 97-98%
weight/power [kg/kW]: 10-6
Toothed belt
transmission ratio optimum: 1-8
transmission ratio extreme: 14
efficiency: 96-98%
weight/power [kg/kW]: 4-0.8
Flat belt
transmission ratio optimum: 1-5
transmission ratio extreme: 20
efficiency: 96-98%
weight/power [kg/kW]: 6-1.5
http://www.mitcalc.com
Mirek
RE: Gear vs Chain efficiency
Hummers use them.
http://thehummerclubinc.com/Tech/tcase/Transfercase.jpg
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If vintage Jeeps used gears, and modern Jeeps use chain, which one has time chosen?
www.skidmore.edu/~pdwyer/amc/ eagle/80eagle2_954738.htm
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Mercedes
www.4x4abc.com/ML320/ txcut.html
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If driving the front half of a Hummer seems like part-time work, My 1980 Yamaha 850 has its original primary (crankshaft > transmission) chain. 42,000 miles.
http://www.yamaha-triples.org/
I think that HyVo chain primary drive is pretty typical on Japanese inline 4 cylinder motorcycles.
RE: Gear vs Chain efficiency
In the last 3 years we have had bouts with 2 large name brand industrial gearboxes that ran at least 5O DEG F hotter than we were "promised." That darned 97% - 98% efficiency figure kept being tossed our way.
A 50 HP rated gearbox with 1/4 HP coming out the output shaft, but using about 6 HP to tear up its oil is NOT 98% efficient. Its more like 5% efficient. All our spindle testing is a operating speed, but not cutting metal. I'm guessing even at full working load it would still lose something like 6 HP to oil pumping/shear, and the efficiency would be more like 85 to 90%.
And, then, when they finally sent THEIR test data, OUR high temps were declared normal. Just last week We received factory permission to run 4X the recommended oil flow in in a desparate effort to help cool the danged thing down. Both are now researching "minimal" spray lubrication as a means to quickly chop the temp back down.
Too late for us.
RE: Gear vs Chain efficiency
RE: Gear vs Chain efficiency
RE: Gear vs Chain efficiency
Which particular non-involute types are you referring to ? Wildhaber-Novikov types perhaps ? You must be involved in very demanding applications to make it worthwhile to consider non-involute types from a cost standpoint, as things currently stand. But I have always been puzzled as to why non-involute types have not made many inroads in this country (USA).
RE: Gear vs Chain efficiency
I was not referring to Novikov gears, although I do believe Novikov gears do have unrecognized advantages. For Novikov gears, I would recommend contacting Dr. Stepan Lunin, his contact information is at www.zakgear.com. I was referring to S type gears, and derivatives of S gears. Researchers at University of Ljubjana in Slovenia have made dramatic advances in recent years. I do not see increased cost for non-involute gears. Actually, if they are conformal, manufacturing costs can be reduced if case hardening can be eliminated, and through hardening to Rc50 is used instead.