Reverse gearbox help!!!

[roodesign]

Hi there everybody, I have a real problem with my build...see it at http://www.roopod.com ...the reverse gearbox that I was trying to use has proven no match for the torque from the kubota z482 cc engine running through a comet 94c cvt. the gearbox, rated at 16 hp did not like the torque from the 13hp diesel, I am now not suprised when I compared the torque from the kubota 22ftpds to that of a gas engine, I had to go up to about 30-35 hp! no wonder...anyway, now I am temporarily putting in a solid jackshaft in place of the comet reverser (internal dog clutch done in) and going without reverse. but I am looking for any and all opinions on a gearbox, electric motor, chains, planatary gears etc , it is no fun to have to get out and push! just for clarity, the gearbox is 1-1 for foward and 3.something to 1 for reverse...help!!! thanks guys, and be sure to check out the site...there is lots of pics and videos etc, I have my headlights going now and am just taillight, indicators and fenders from being able to get inspected! Roo

[roodesign]

...by the way this problem is limited to the forward drive! reverse engagement by sliding gear is fine...just the strait through for forward is the problem! the dog clutch has teeth that have (had) a slight undcut and now are rounded over! they are only about 1/8" tall and there are only three...I will put some pictures up later today of the guts inside in case someone has any ideas.


roo

[IgorVigor]

I am surprised in a way that forwards has gone, 1:1 is a decent heavy duty ratio ...

tbh, reverse will probably fail soon as well....

its just you dont use it as much

as for options, Quaife Engineering (UK) make a reverser box for Motorbike engined cars (basic gearbox with a lever that swaps drive to reverse)
They can take a lot of torque and power. They use them on Hayabusa engined cars... I havent personally had anything to do with them (no need to...)
but they are meant to be very good... and if you had a manual gearbox, you get as many reverse gears as forwards

apart from that, you could fit an electric motor as a reverser, but I personally think its more to go wrong :S

I dare say someone else will be along to add some more ideas

[albertaphil]

Many snowmobiles have a reverse gear (mechanical or electric) and although many snow machines appear to be as heavy as a locomotive, a lot of the enthusiasts are more particular about weight than dieselbikers are. Perhaps if there is a snowmobile wrecker around you might have some luck. Of course snow machines all have CVT's so the apparatus would probably be adaptable to the Pod.

Phil

[pietenpol2002]

Roo,

I'd wonder about using the gearbox out of something like a Polaris 4 wheeler. They are a forward/reverse box with some having a 2 speed forward option (sadly, you can't shift the 2 speed on the go). Most also mount the CVT directly to the input shaft as you have. The older 2X4 trans would be ideal given that you don't need more than 1 output shaft. However, I'm not certain the older ones would be up to the torque loads. The newer 4X4s put out a good deal of power and thus may be up to the task. You'd have some losses due to the unused output shaft (or just tap it for a bullet-proof speedo drive). All those boxes are commonly available on Ebay or through bike/atv salvage yards. Below are several examples.

Thanks for keeping us updated. Great build you've got there.

http://tinyurl.com/28f2cqn
http://tinyurl.com/2a5jvun

[pietenpol2002]

One point I failed to add that would be really cool for your application is that the Polaris Ranger RZR 800 trans example from my earlier post has park, reverse, neutral, low and high. And that particular trans is put behind something in excess of 50 hp.

[roodesign]

Wow, thanks everybody for the ideas so far...I am going to look at those atv transmissions a littler closer, and I have found what I think would be the perfect unit, but it is $$$ 1000.00 $$$ see it here http://www.novaracing.co.uk/reversing-g ... ng-kit.htm I called them and they will make it up with a sprocket on one side and a shaft for the cvt on the other...just have to scratch togther my pounds! anybody over there have experiance with these guys?

thanks again...Roo

[coachgeo]

Wow, thanks everybody for the ideas so far...I am going to look at those atv transmissions a littler closer, and I have found what I think would be the perfect unit, but it is $$$ 1000.00 $$$ see it here http://www.novaracing.co.uk/reversing-g ... ng-kit.htm ...just have to scratch togther my pounds! ...

Surely there is something similar in US.

[coachgeo]

IMHO your best route while your saving euros (or usd's) and or searching other options is to just drive one wheel with an electric Starter motor for reverse. Simplest addition to what you have now.