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conical pinion and gear set up

3069 Views 28 Replies 12 Participants Last post by  stoner
the new black arrow car has a conical pinion and gear set up. is it like the old brass setups or is it to get perfect gear mesh with a normal toothed crown gear. or move it off centre. is there an advantage over the old brass setups, where you have a lot of contact area. john
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Bevel gears can be made with the centres in line or with off set centres. (The off set ones are also known as hypoid )

Theoretically a crown gear and parallel pinion isn't a very satisfactory gear arrangement because the teeth on the crown have to get closer together as they get nearer the axle, the teeth on a parallel pinion don't. That means the pinion teeth can only be the correct size for the crown at one diameter. Making both gears conical means they can be made so the teeth match properly across their complete width.

Bevels should be better and if you look inside how 1:1 car transmission turns the drive through 90 degrees and you'll find they almost always uses some variation on bevels.
Bevels have been used many times before on slot cars. Getting the length ways position of both axle and pinion correct is important to getting bevels working correctly, where as it doesn't matter much with parallel pinions. Crown gear and parallel pinion set ups seem to work well enough on slot cars whatever the theoretical disadvantages.

How well a particular make of slot car gear works largely depends on the quality of design, manufacture and materials rather than the basic type. Anybody like to offer any experience of Black Arrow

EDIT Looks like Bill and I were typing replies at the same time - fortunately we don't seem to conflict
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Hi John
I'll have a go at explaining what I meant.
Imagine a crown with a 60 mm outside circumference and 30 teeth. The teeth are 2mm apart.
Imagine the teeth go in for 10% of the diameter, The circumference of the inner end of the teeth is 54mm but there are still 30 teeth. So the teeth are now 1.8mm apart.
The best you can do with a straight pinion is to mesh with teeth 1.9mm apart, that's not quite right at the outside where the teeth are 2mm apart nor at the inside edge where the teeth are 1.8mm apart.

Did that make it clearer or leave more confusion?
I was talking about crown gears (Not conical gears) and straight pinions.
Sorry if the description doesn't help - guess a drawing would make it clearer, unfortunately my drawing skills would need some honing.
QUOTE (Russell Sheldon @ 21 Aug 2012, 16:10) <{POST_SNAPBACK}>Now, if anyone can tell me why the Eurosport racers all use 72DP pinions with 64DP gears, that would enlighten me further!
All the Eurosports tech charts I've seen recently shows the finalists using 80 pitch spurs and pinions.
Where do they use a 72 / 64 mix?
What's 1/32 F1 Eurosports?
Internationally, Eurosport is a sports car class for unlimited motors, although the motor position is unlimited they are almost always low angle angelwinders
Most but not all 1/32 F1 rules require inline motor position. Different rules have different motor limitations.
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