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I have a question what is a difference or advantage for using two gears with high gear ratio or using three gears with lower gear ratio.Is there any advantage.
It depends on the overall ratio required. What ratio do you need?Datt said:Is there any advantage.
That heavily depends on the gearbox.Baluncore said:Welcome to PF.
It depends on the overall ratio required. What ratio do you need?
The lightest weight and most economic gearbox will have pairs of gears, that each give a reduction ratio of about three. That comes about by considering the size and strength of the teeth.
If the ratio is greater than about 5.2 use more than one pair.
There is no simple answer to your question. A complete answer depends on the ratio, power, speed, size constraints, efficiency constraints, cost constraints, and more. If you get a copy of Dudley's Handbook of Practical Gear Design, and read the entire book, you will be able to understand just how difficult it is to answer your question. The book is available from Amazon: https://www.amazon.com/dp/0367649020/?tag=pfamazon01-20. I read an earlier edition, and highly recommend it for completeness and readability.Datt said:I have a question what is a difference or advantage for using two gears with high gear ratio or using three gears with lower gear ratio.Is there any advantage.
Planetary gears are used on coaxial shafts where side forces need to be minimised. The planetary reduction unit can still be smaller and lighter again when an axial stack of planetary gears is used, rather than only one high-ratio planetary stage.cjl said:For very high reduction ratios, planetary gearboxes can achieve much larger reductions than that in a single stage, which can end up more compact and lighter than a multistage conventional gearbox with a similar reduction ratio.