2 speed gearbox

[nielsvdv]

hi, i was experimenting with buidling a simple 2 speed gearbox for trucktrial. i wanted the 2 ratios to be not to far from eachother. this is the result:

http://www.brickshelf.com/cgi-bin/gallery.cgi?f=448047

my question is, has anybody ever used this setup? i have never seen it anywere :s

the gearbox output is 1/1.536 or 1/2.5

it works perfect and has low friction, it is now in my prototype trucktrial installed and gives it a nice 1/7 and 1/12, suited as high and low gear.

grtz Nielsvdv

[Sariel]

Sorry, but it will come apart instantly in serious Truck Trial. Two reasons:

- you're using a driving ring which can't handle high torque. All Trial Trucks I've seen in Poland use linear gearboxes because driving rings pop out or get damaged under torque

- the gears are not reinforced properly: there is no single part that would connect them and prevent them from coming apart. Instead, there are many small parts that will bend and slide, and your gearbox doesn't even have a transverse reinforcement.

Also, from my experience, if you have just two gears in your gearbox, their ratios should differ more. If they only differ a little, then it doesn't really pay off to have such a gearbox. You should think of having one gear for going uphill and one gear for going downhill. I'd say 3x difference in ratios is minimum for the gearbox to be useful.

Take is as an advice from someone who tested a lot of gearboxes under high torque :)

Edited October 12, 2010 by Sariel

[allanp]

I like it, but like it has been said above you do need some re-inforcement. But the driving rings should take the strain as long as you are not driving it with an XL-motor. An RC buggy motor would be good for this gearbox providing all other gearing down is done after this gearbox and your gearbox is re-inforced. Good luck!

[nielsvdv]

I like it, but like it has been said above you do need some re-inforcement. But the driving rings should take the strain as long as you are not driving it with an XL-motor. An RC buggy motor would be good for this gearbox providing all other gearing down is done after this gearbox and your gearbox is re-inforced. Good luck!

the gearbox in the picturewas just the concept to ilustarte it. the one i have in my trialtruck is a reenforced one. it actually is driven by one xl. but the truck only weighs 1.4 kilo with batteries and al. i am using a beam to hold the gearlever in place when in gear. the driving ring never slides out, and after a lot of testing i find no difference in a new and the used driving ring. it works fine, this 4x4 is driving on 91.4 tyres, so takes some stress...

@sariel: why i wanted a close gear ratio for trtr, i live in belgium and there is a trucktrial cours at the next event of belug. the course is going to be made with lego bricks, the obsticles will be very close togheter. as they are build with bricks, there wil be not a lot of flat surfuces, even on the downhils. so if go downhill, i dont want to triple my speed, because the next obstacle will come right after it. taking in mind that the course track isn't gonna be wide because of the lego struture, speed an various bumps on te downs will be a high risk of ending next to the track...

i rather play safe and be sure to be able to end my run :)