Thread: hair-brain half-baked idea coming right up

I like Dave's idea of using the Annulus and planetary gears... I drew them up using CAD again and i realised one flaw, the casing will stick out a long way down as it is the output of the annulus that hooks up to the diff and not the planetary gear. So while it would be more mechanically efficient, you will have problems with it being hit and getting hung up. Well.. unless you hook it up to salibury, in which case if you are going to get hung up on this casing you would definitely get hung up on the diff anyway!

This is what a 3:1 reduction setup would look like. The outside diameter of the annulus is 150mm and the input and output shafts are 25mm. I chucked in some needle bearings this time

Nice drawings Sterling however I think Dave was suggesting not to use the outer gear centre where the sun gear would be as the output shaft as you need a big box and dont use all the potential lift. If you add another planet gear at the bottom being rotated by the annulus you get the same direction output and the same speed with more offset. Also for strength I am not sure how good it would be with the shafts not going all the way through the block with a bearing at each end. There is a lot of weight.

And rangier rover, I was under the impression a chain would do the job as well, but some people had evidence to say it does not. A powerful road bike chain certainly takes a lot of power (100hp+) which is a lot more than a 3.5L v8 rover after transmission and divided by 4 (excepting low first which probably equates to approx 2 - 350nm per wheel). Some harleys use belts for transmission.

I'd buy Unimog portal boxs and mount them onto the ends of the Rover axle and flip the diff centre and just enjoy it. It'll also be a lot easier to gain engineering approval and you will have brakes and a setup that is proven. It also removes the complexities of designing and building steering.

Actually... if you hunt around, Volvo's would be even easier.

thats so close to what I was thinking its outright scarry and the basic idea is perfect But instead of a square casing I was going to utilise a rounded one, my plan for the system included about a 20 inch diameter rim and then internally about a 16 inch diameter anulus gear with a 5 inch planetry. with the outside diameter being some 18 inches giving about 2 inches of clearance to the rim.

I had planned for the singe planatery gear to be supported by a bearing on both sides on a shaft similar to how drive is currently transmitted to the hub va a flange but instead of bolts to mount the drive flange to the planetry they would be a dog pin interface setup. in theory this means that your hub centerline only increases in width by a couple of inches and that could be easily pulled back by use of a suitabley profiled wheel rim.

brakes would be proviced by a wet band brake that was actuated by your normal hydraulic system that applied the band onto the circumference of the annulus.

how about you hollow out the annulus and put jockey wheels in each corner to support it, then you can put straight through axles on planetary gears to support the cars weight better. All the gears could be helical I think as spur gears would sound like your driving in reverse all the time and wear faster.

also you could make the input and output planet gears any size you like to make a reduction.

I'm an idiot.

I just realised that we are talking about these thing being fitted on either end of the axle... Input from the halfshafts and output to the wheels.

I was initially thinking that this was taking the input of the drive shaft and output to the diff.... not that it changes much.

I found this link here under the articulation pix's.

It's not machined it's fabricated.

Bill's LRs - LR4x4 - The Land Rover Forum


Cheers Mick

Originally Posted by stirlsilver

I'm an idiot.

I just realised that we are talking about these thing being fitted on either end of the axle... Input from the halfshafts and output to the wheels.

I was initially thinking that this was taking the input of the drive shaft and output to the diff.... not that it changes much.

well that explains why I was confused at your 'getting hung up' points.