Joining two gearboxes

I'm confused as to how you will achieve infinate crawl and very high overdrive at the same time. You can one or the other but not both unless you are using two OD transmissions. ????????

Idunno about "infinite" crawl, but I'm thinking that slapping both gearboxes into first would give some fairly serious "Oomph". Then there's #1 in 1st, #2 in 2rd for a little less grunt and a little more speed, and so on up the line. Likewise, putting both gearboxes into 5th should yield one monster of a big overdrive. Putting a high/low xfer case behind 'em both would give even more speeds to play with.

To the OP: I'm assuming that it's *REALLY* a pair of 6 speed (5 forward, one reverse) gearboxes you're thinking about mating.

The question, however, is whether the second gearbox and/or the xfer case would be able to take its input from the first gearbox (or both gearboxes, when speaking of the xfer case) without self-destructing.

Next problem I see is taking power off the first gearbox and feeding it to the second. You're going to need some kind of clutch mechanism back there if you plan on being able to shift both of them while in motion. Otherwise, it's "come to a complete stop" to shift one or the other of them. With two clutches and a shift-on-the-fly hi/lo xfer case, you'd have what amounts to a 5 speed with a 10-split rear end. Yoiks! That's a total of 50 forward and 20 reverse gears, and two Idunno-what-to-call-'em speeds that should move the vehicle forward. (both gearboxes in reverse, with the hi/lo giving you two versions of it

- wonder what the proper thing to call that would be? Other than "monstrosity", I mean!)

Dunno if trying to run a tranny backwards from what it was built to cope with would be a good idea. I can see problems from the oil not getting slung in the right directions, missing channels that are supposed to guide it into bearings and such, and the bearings (or their mount parts) not being able to handle the different stresses going the wrong way might produce.

That rig might be... "interesting"... to drive! Interesting in the same sense as that old and honored curse "May you live in interesting times", that is!!! :)

Then again, a rig like that would probably take a teflon-lined swamp to get it stuck... :)

Thanks for the replies. I mean two five speed gearboxes, not counting reverse, mated together so the output from the first goes into the input of the second. Around town driving and you would leave the second box in fourth which is 1 to 1 and just use the first box. For cruising, the first box would end up in fifth gear while you would then put the second box in fifth. I assume using the clutch as normal - and you would be able to operate the second box. For 4 x 4 land the first box would be in first - say 3.5 to 1 ratio, low in the transfer case, lets say another 3.5 to 1 ratio and if you needed it you could put the second box into first adding yet another

3.5 to 1 ratio. Crawl ratio would be 3.5 x 3.5 x 3.5 plus axle. Would it work, excluding engineering problems.............

Smokeyone

Think about the big picture. If you need such a myriad of crawling gears, ya must have some kinda strictly off road machine & do ya really wanna drive such a thing as fast as those overdrive gears are gonna make it go???? Good luck.

Hello again

Another newsgroup reader suggested getting hold of a Spicer three speed auxiliary transmission - underdrive, 1 to 1 and overdrive all in one unit. Is anyone familiar with these units.

Smokeyone