benefits of gearbox vs belt drive reduction?

[ebiker1]

i've been following the gng threads for awhile and i'm still not sure why everybody is trying to use the belt-driven reduction setup. there seems to be a lot of problems with getting it to work reliably and some are even changing the belt drive to chain. with all these problems, why not just go with the gearbox reduction like cyclone or ego-kit? i have a gng belt drive kit because i heard so many people trying it on ES, but haven't got it running yet, so haven't experienced any of the problems yet. i have started to question whether i should continue with it or pull it off and sell the kit untried. i realize the belt drive is a brushless motor, but how hard is it to change those brushes? and why not buy cyclone or ego-kit, they are brushless. Any thoughts on this???????

 

[spinningmagnets]

There's nothing wrong with a gearbox. They are somewhat noisy (electric drill noise), and they are difficult to change the tooth-counts. Helical-cut gears (as opposed to straight-cut gears) are quieter, but again few provide that, and the few that do may not be available in the size and tooth-counts you want.

Staton-inc.com has several variations of their gearbox, they have an 18.7:1 with 1/2-inch shafts for $204. It's made for gasoline "chainsaw" kits, but they are starting to carry some electric stuff, and recently even a BB-drive kit.

http://www.staton-inc.com/store/pro...Three_output_shafts_1_2_Mid_Drive-872-27.html

 

[Thud]

One of the key design concerns of using gears is having some shock absorbsion built into the drive train.

Gears are frail when subjected to spiking shock loads. I steer away from them for that & the critical center to center distance required to have them functioning correctly.

They also are not tollerant of grit & dirt & require constant lurication to enjoy full efficancy adding to the complexity of requiring a well sheilded or seald box to house them.

typicly, gears will be heavyer than a compairable chain & sprocket for the same tourque handling capacity.

For a simnple reduction set up, it is hard to beat a chain & sprocket or a toothed belt when considering the size constraints of powering a bicycle.

The issue with the GNG belt drive is incompatability of the center distance w/regard to belt wrap on the drive sprocket. They are fighting for too much reduction in the space allowed & are using a whack tensioner that is over stressing the belts with radical bending back on itself generating too much heat.

guys running them at 36v arent having any problems......

JMHO.

 

[parajared]

the weight, complexity, reliability, and noise of a gearbox is worse than belt reduction, but they seem to me like the way to go for high wattage builds.

Something like a motorbike transmission can handle tons of power.

 

[Whiplash]

In my opinion SIZE is where they shine, but they are difficult to machine for clearances as Thud pointed out and require an oil bath to work right. I built one on my mill and it performed well but the RC motor was too noisy in my opinion...

 

[gwhy!1]

I have used MOD1 AND MOD1.5 gears and both worked well for my rc drives for the initial reductions , centre to centre needs to be spot on to work well like Thud has said, noise is more of a issue unless running in oil and there is no resonance of the casing that is enclosing the gears. Heli gears are quieter but design becomes even more of a issue as thrust bearings are also needed for it to be reliable the efficiency is not so good as straight cut gears. Gears are heavier than belts or chain but far more robust and more maintenance free if you can run the gears in oil then its worth the extra hassle to make.

 

[spinningmagnets]

Here's one effort to use a pocketbike transmission as a 5:1 reduction, but buy page two (of 7 pages), he had gone to a chain for both the primary and secondary reductions.

http://endless-sphere.com/forums/viewtopic.php?f=28&t=29531

 

[crossbreak]

Ok now it's my turn... I learned that gear reductions are more compact. The most compact gearboxes known to mankind are planetary gearboxes and all variations (cycloid drive, harmonic drive...) but the are they most expensive. They can be even low noise if they are helical geared, but that makes them even more expensive, there are additional bearing forces and are though less efficient as already said. You can sell a small planetary gearbox and overload it for a good price, this is what cyclone does. Then you get a very compact drive that will not last long. The cylcone was once designed for 250Watts i guess.

Belts are good cause they dont need no lubrication. Thats a great advantages in the hazardous e-bike environment. They do less noise than straight cut gears and chains (if engineered right - dont compare the GNG), thats also a plus. Efficiency is also ok, worse than a oil-bath chain but better than an almost unlubricated one (like most bike chains). Also acoustics and resonances are very important in machine engineering. Belts are best in acoustics. Due the built-in rubber damping there is almost no noise.

The most simple type of reduction is the chain. Still more compact than belts in most cases. If lubricated and separated from dirt by a chain guard, this is the non-plus-ultra in DIY environment. Gains up to 98% efficiency. BUT chains need tensioners if dirven faster than a few inch per second.

i have started to question whether i should continue with it or pull it off and sell the kit untrie

sell it too me cheap! I'll warp a chain on it

 

[ebiker1]

i will probably just be commuting with this kit. my reasoning is that i weigh 215 and live in a hilly area. so i'm not going to be subjecting the bike to the rigors of offroading, hence not as much wear and tear on it. but, i read in one of these threads that this kit is not really for commuting. do you think that is a good assessment? cause if it is, i should probably stop at this point, sell the kit and put the money into more battery for my bmc 2 thunderbolt. is it just the gng or would the ego-kit be a acceptable alternative, reliability and performance wise, notwithstanding the cost?