Portal Axles #UltimateLift

So I was thinking about making some portals for my tractor.

For those of you who want to know what they are click Here.

Here is my basic rundown: Unimogs have been using them FOREVER! They basically take the output of the rear axle, the axle shafts, and use a box with internal gearing to simultaneously drop final drive ratio and locate the output of the box lower than the axle, giving you lift.

I want to make rear portals so when I say my tractor is lifted, it's not just some useless rear body lift. The portals will locate the transaxle higher up, giving you more ground clearance. Ground clearance is very important to me. I don't care too much for body lift.

Here are some problems I have ran into when thinking about this:

1. Getting gears cut.
   
2. Mounting the gears to axle shafts.
   
3. What to use for bearings to support shafts.
   
4. Making the portals strong enough.
   
5. Mounting the portals to the transaxle (I was going to use an 820-016C).
   

Here are my solutions so far:

1. Repurposing gears from scrap transaxles.
   
2. Making a Doc Locker and custom cute axle ends so they barely stick out the transaxle. I was thinking of either spline or some sort of keyway to attach the gears to the axle.
   
3. Pillow blocks? Possibly make the housing to hold the bearings.
   
4. Gussets. That's all I've thought about.
   
5. I was going to make brackets that come off the portals to utilize the mounting holes on the transaxle and possibly drill holes in the frame of my tractor.
   

I'd really like some input. I was told by someone else that they were thinking of using chain instead of gear to gear to transmit power, but I don't think I wanna go that route. It just doesn't seem strong enough. But it is just a tractor with like 20 hp max. If I use gear to gear then I will have to have three gears instead of two so that when the axle in the transaxle spins clockwise the wheel will also spin clockwise. The chain will eliminate the third gear and it will be easier to get the exact amount of lift I want instead of trying to get the right size gears in the right places to give the desired lift.

You would need 3 gears, one on the drive axle, an intermediate, and one on the driven "axle". Otherwise you would be going backwards.

Chain would probably be a lot easier, and you could make a crazy high rig. Like the Farmall Cubs had.

Do it! I would love to see it Done!

Doug Fackler wrote:

You would need 3 gears, one on the drive axle, an intermediate, and one on the driven "axle". Otherwise you would be going backwards.

Chain would probably be a lot easier, and you could make a crazy high rig. Like the Farmall Cubs had.

Key point about the 3 gears, yes.

I too was going to point out that folks have done this with chain many times in the past. I would sure like to see a geared solution. Potentially stronger, and maintenance free.

The front axles on my 4x4 Yanmar (future repair project) are very cool. At the end of the axle is a pair of bevel gears, which orients the shaft DOWN. 6" or 8" down from there is another pair of bevel gears that brings the drive out to the hubs. It goes a little beyond portal axle, but too dang cool at any rate.

Ive said before, but i should explain a little more. i feel as if custom cut gears or mower axle gears working together within a machined case would be a lot of chance for breakage to happen. like hell, in FACTORY made cut gears in transaxles they strip, crack, and other horrific things.

Bolting to the tranaxle would be a bad thing because of all the anti travel this thing will want. its gonna try to drive right under itself when you pop the clutch, and that aluminum casing at the thinnest part, the ends, will not like any of that.

I usually shoot the ***** with other people on cool mower concepts that are over the top. When i thought about portals this is what i was thinking.

No argument here, and some good points made.

Personally, I'd advise against using factory spur gears, unless you can positively identify them as being forged and cut, rather than sintered as most are.

Doug Fackler wrote:

You would need 3 gears, one on the drive axle, an intermediate, and one on the driven "axle". Otherwise you would be going backwards.

Chain would probably be a lot easier, and you could make a crazy high rig. Like the Farmall Cubs had.

The 3 gears thing was already thoght about. As far as makig it super high, I was going to make the whole assembly fit within the rim so that it wouldn't have parts at the same height the transaxle was.

Doc Sprocket wrote:

I too was going to point out that folks have done this with chain many times in the past. I would sure like to see a geared solution. Potentially stronger, and maintenance free.

I was wanting to make a housing out of aluminum or an equivalent that unbolts on one side to allow me to access everything. I wanted to tap a drain hole on the bottom and a fill hole on the side so I can also monitor oil levels. Shouldn't have any more maintenance than a regular transaxle would. Preventative maintenance is the best maintenance, which is why I wanna plan everything out and do it right the first time.

If youre going that far, might as well do chain. Less moving parts, and you can lift it to virtually any height.

I would also suggest chain because the only way your going to bulletproof a portal is around 300$ per side because your going to have to have helical cut gears if you want any kind of life out of them your going to need a steel housing and a lot of bearings :> I was talking to some people at wauseon machine and a couple gear and tool companies around here trying to get ideas for a pulling tractor tranny reduction unit of sorts same thing as a portal but instead of going up your going back and reducing the gear. And that was only with two gears per case not 3.

You could do it with just 2 gears per side... You'd just have to spin the transaxle so the front is pointing back (input still on top). If you're engineering at this level, I don't think the mounting and linkage to turn the trans around would be out of your league.

You wouldnt really have to turn the tranny around there is always the deep dark option of turning your motor around and spinning the input in the opposite direction or if you run a vertical shaft you could put in a gearbox.

Moose wrote:

I would also suggest chain because the only way your going to bulletproof a portal is around 300$ per side because your going to have to have helical cut gears if you want any kind of life out of them your going to need a steel housing and a lot of bearings :>.

Transaxles have straight cut gears and I have yet to strip a single one. Heck, when I took the Spicer apart I couldn't even see any wear. The only reason I'd go to helical cut gears is if the straight cut gears were too noisy.

TheRainbowBoxer wrote:

You could do it with just 2 gears per side... You'd just have to spin the transaxle so the front is pointing back (input still on top). If you're engineering at this level, I don't think the mounting and linkage to turn the trans around would be out of your league.

Spinning the transaxle sounds like a really good idea. I never thought of that.

Moose wrote:

You wouldnt really have to turn the tranny around there is always the deep dark option of turning your motor around and spinning the input in the opposite direction or if you run a vertical shaft you could put in a gearbox.

Rotating the transaxle seems a bit easier. Lol.

LAWN MOWER MUDDER wrote:

Moose wrote:

You wouldnt really have to turn the tranny around there is always the deep dark option of turning your motor around and spinning the input in the opposite direction or if you run a vertical shaft you could put in a gearbox.

In order to spin your motor the other way you'd have to flip it upside down and run a pulley off of the flywheel. LOL

Not what he was talking about: you'd have to get a gearbox that reverses the input.

Chains seem cheaper, easier, stronger IMO. Lots of things that can go wrong with gears.

redlinemotorsportts wrote:

Chains seem cheaper, easier, stronger IMO. Lots of things that can go wrong with gears.

Two gears with a rotated transaxle seems cheaper, easier, and stronger. I won't have to worry about snapping chains. I'll just have to find two of the same transaxle if I want to go that route so I can get matching sets of gears.

TooIngenious wrote:

redlinemotorsportts wrote:

Chains seem cheaper, easier, stronger IMO. Lots of things that can go wrong with gears.

Two gears with a rotated transaxle seems cheaper, easier, and stronger. I won't have to worry about snapping chains. I'll just have to find two of the same transaxle if I want to go that route so I can get matching sets of gears.

You WHERE looking for imput, were you not? Whats so bad about chains?

Itll take A LOT to snap a #40 chain.

Doug Fackler wrote:

Itll take A LOT to snap a #40 chain.

I can understand that. Another thing I was thinking of is space. I want the whole assembly to sit inside the rim. My rims are 10". I probably have enough room for about a 2-3" lift. If I used chain I would be concerned of the space between the sprockets.

TooIngenious wrote:

Doug Fackler wrote:

Itll take A LOT to snap a #40 chain.

I can understand that. Another thing I was thinking of is space. I want the whole assembly to sit inside the rim. My rims are 10". I probably have enough room for about a 2-3" lift. If I used chain I would be concerned of the space between the sprockets.

Not to be salty, but is it all really worth for 2-3" more of clearance? If i cant make it over something i just pick a different line. Unless you just want them to say you did it.

Well I would use the video of the 820 I got off facebook as reference for blown gears but that was only 6th gear and you would be suprised how easy it is to strip the teeth off the stock gears lol I got a 4360 that stripped out second and third.

Took a quick look at the 10" rims on my simplicity I hate to be the bearer of bad news but youd be lucky to fit 2 gears in there if they are anything like my rims its like 5" in diameter at the hub so you have around 2.5" between your axle and the inner wall of the rim.

If youre aiming for such a mild lift, get a tire thats 6" taller than your current ones.

Aside from the "cool" factor or the "I did it first" factor, for such a mild lift its not really all that practical for such a slight amount of clearance. Having all that stuff in the rim will increase stuff being caught and mud caking up inside too. A 1/8" thick skid plate would be more practical.

I was thinking if you did this of using trans gears too, but the more I think about it I dont think thats a good idea if its a sintered steel gear. Theres a lot more stress being put on them if you only use a few. In the trans they all kind of share the torque.

Moose wrote:

Well I would use the video of the 820 I got off facebook as reference for blown gears but that was only 6th gear and you would be suprised how easy it is to strip the teeth off the stock gears lol I got a 4360 that stripped out second and third.

Took a quick look at the 10" rims on my simplicity I hate to be the bearer of bad news but youd be lucky to fit 2 gears in there if they are anything like my rims its like 5" in diameter at the hub so you have around 2.5" between your axle and the inner wall of the rim.

My 4360 was doing quite well when I tore it apart, but it just has a mild pulley swap. My 10" rims aren't your rims. I have golf cart rims on my tractor.

Doug Fackler wrote:

December 19th 2014, 23:58
If youre aiming for such a mild lift, get a tire thats 6" taller than your current ones.

Aside from the "cool" factor or the "I did it first" factor, for such a mild lift its not really all that practical for such a slight amount of clearance. Having all that stuff in the rim will increase stuff being caught and mud caking up inside too. A 1/8" thick skid plate would be more practical.

I was thinking if you did this of using trans gears too, but the more I think about it I dont think thats a good idea if its a sintered steel gear. Theres a lot more stress being put on them if you only use a few. In the trans they all kind of share the torque.

The whole point of a portal is to give you more lift. Even 3" helps. 3" portal lift coupled with 6" of extra tire height is better than 6" taller tires. I never thought of the point of the gears sharing torque. I guess I'll have to find transaxle gears that aren't sintered? What other kinds are out there?

Milled steel. Pretty uncommon though. Might be able to find something in heavier equipment.

Doug Fackler wrote:

Milled steel. Pretty uncommon though. Might be able to find something in heavier equipment.

My friend's dad has a machine shop. I'll see what he can do.