Portal axle box using chain (1 Viewer)

[Arya Ebrahimi]

The main advantage I see to the chain setup is that the portal housing isn't trying to blow itself up constantly(from gear spread). The rotation issue is one of the advantages I see with a traditional geared portal setup as it allows you to take a LP diff, flip it over to reverse the rotation, gain ground clearance and maintain the strength of a LP diff.

I also think if you were to find a magical chain that would hold up to this, that it would be easier to put the knuckle outboard of the portal box and run large diameter wheels with a large offset so that they sink back around the portal box.

 

[liljlandon]

Why? At 1:1 the only power loss would be in the gear/bearing friction. Its just more for the power to move through
A reduction gearing would result in power loss, ie more revolutions to cover the same amount of ground.It would result in speed loss, but more torque. Itd be no different than switching into 4lo, right?

16" may be a bit much, what if we combined both worlds in order to split the power between gears and a chain?

pardon my quick drawing on CAD, its no where near the state of my portal box!

 

[Toyo Boyo]

Sometime in the 80's there was a company here in the UK fitting chain driven portals to LandRovers and calling them the agri rover (ag-rover)

Second part of this link ::: Land Rover Madness - Have you got it? - Forest Rover & Ag-Rover :::

with a pic of the portal too

I'll see what else I can find out about these.

 

[concretejungle]

Hey Brian, what about a planetary gear at the hub like what's used in monster trucks? I was looking at that the other day and found it pretty fascinating. With the huge tires and over a thousand horsepower running to these tires, they are not popping axles because of the planet gear reduction. It appears it's built right into the hub. Pretty interesting.

http://www.youtube.com/watch?v=a1JAWoAvK-E

 

[Toyo Boyo]

16" may be a bit much, what if we combined both worlds in order to split the power between gears and a chain?

The tooth form cut onto a gear that's used on Morse TEC chain is not a normal involute profile. It is more of a wierd 'wavey' pattern, with a rounded root and crest on the tooth profile. So putting an extra pinion in there wouldn't mesh properly.

Hey Brian, what about a planetary gear at the hub like what's used in monster trucks?

Placing a reduction hub in there has been mentioned earlier in the thread.

That why I mentioned that a portal axle is very similar to a transfer case as used on some 2WD Broncos - one example is the Borg Warner 1359 transfer case.

I like that video - very concise.

 

[concretejungle]

Placing a reduction hub in there has been mentioned earlier in the thread.

That why I mentioned that a portal axle is very similar to a transfer case as used on some 2WD Broncos - one example is the Borg Warner 1359 transfer case.

I like that video - very concise.

Sorry, i kind of skimmed over some of the threads.

 

[Toyo Boyo]

Sorry, i kind of skimmed over some of the threads.

LOL - I do it all the time!

 

[Jetboy]

The idea of a chain/gear drive combo sounds pretty interesting even if you'd have to overcome the tooth interface problem. Might be a way to split the forces up and end up with a lighter unit. The problem I see is that it just gets more complex and therefore more $.


Are the silent chains from a transfer case stronger than a traditional roller chain? Just looking at tensile strength of regular roller chains a size 200 ~2.5" width has a tensile strength of 78k lbs and a "working load" which IIRC is calculated for low speed operation, of 16k lbs. If you could increase the final drive or output gear to 10" or larger it might get you into the range of being strong enough and only 2.5" wide chain. Of course the roller chain probably isn't as good for high speed applications? I'm no chain expert, or even chain novice for that matter. Just throwing out something to consider.

 

[liljlandon]

The idea of a chain/gear drive combo sounds pretty interesting even if you'd have to overcome the tooth interface problem. Might be a way to split the forces up and end up with a lighter unit. The problem I see is that it just gets more complex and therefore more $.


Are the silent chains from a transfer case stronger than a traditional roller chain? Just looking at tensile strength of regular roller chains a size 200 ~2.5" width has a tensile strength of 78k lbs and a "working load" which IIRC is calculated for low speed operation, of 16k lbs. If you could increase the final drive or output gear to 10" or larger it might get you into the range of being strong enough and only 2.5" wide chain. Of course the roller chain probably isn't as good for high speed applications? I'm no chain expert, or even chain novice for that matter. Just throwing out something to consider.

Where'd you get this info? Id be interested. I think there is a way to get around the chain issue, but as you stated, it just becomes even more complex. I want a unit that would retail for under a grand. (tough luck so far)

 

[bustanutley]

Will the stock toyota knuckle assembly (bearings and all) support a portal box?

no

 

[craptabulous]

Never heard of a Morse TEC chain breaking. Are they being broken when used in rock crawling rigs or some similar extreme app?

Correctly specced - yes I do think they could handle extra torque, they come in some hefty sizes.

From what I can see in this portal, the reduction is between the driven and drive cogs, the left and right cog look to be the same diameter as the drive, they must be there to spread the loading across more teeth.

If those cogs were replaced by a chain you get the same type of drive but the loading on the teeth would be lower, how much chain wrap you engineered into it kinda thing

Anyway, I think there is some milage in this idea.

To me a portal is very similar in layout to a transfer case - you put drive into one shaft, either cogs or chains transfer the torque, and ultimately drives another shaft (that is on a different centreline).

Wasn't there a transfer case used on a 2x4 Bronco? Same idea

those two gears are actually there for a direction change , any time you have an idler gear it changes direction .

if it just went gear gear it would come in forwards and send it out backwards with the idler it comes in forwards idles and goes out forwards .

 

[bjowett]

When you have some time, wander around this page for a bit. Plenty of good info.

Ramsey Products | Ramsey Silent Chain and Sprocket Solutions

 

[Toyo Boyo]

The obvious advantage of a chain v. direct 2 gear drive is that you don't need a reverse rotation r&p.

Not if you are a 'chain' guy and its late at night - doh - I hadn't thought about rotation (too many thoughts in me head) lol

those two gears are actually there for a direction change , any time you have an idler gear it changes direction .

if it just went gear gear it would come in forwards and send it out backwards with the idler it comes in forwards idles and goes out forwards .

I've already accepted responsibility for my oversight earlier in the thread- no need to rub it in. I'll be voted Idiot of the Week soon lol

One idler on its own would have changed direction, the second one must be there to spread the load across more teeth.

 

[Jetboy]

I've already accepted responsibility for my oversight earlier in the thread- no need to rub it in. I'll be voted Idiot of the Week soon lol

One idler on its own would have changed direction, the second one must be there to spread the load across more teeth.

FWIW I didn't catch that part of your post till you pointed it out. And roller chain tensile strengths can be found just by googling them. I'd ask the manufacturer specifically though to be sure. The interesting part in reading a bit about them is that you use a formula for the chain speed, angles of interface with the sprockets and probably other factors as well. It seems that with roller chains when strength is plotted as a function of speed they actually have a peak. As speed increases you can use a lighter chain until a certain point where any more speed requires a stronger chain because there are multiple parts of the chain that may fail and the weak link ,pun intended, changes from the side links to the rollers, or something like that.

Anyway I'd be careful if you do consider a roller chain to make sure the speed range is correct. Just off the top of my head it seems like it should be because the speed should be slower than that used in motorcycle/ATV drive applications.

 

[Mace]

I'm in agreement with mark, the back is easy. The front is where I'm stuck.

Will the stock toyota knuckle assembly (bearings and all) support a portal box? I can see chopping it off and going with a similar set up as others, but having toyota all the way is my goal.

no

The pimp makes a very good argument.

It is not difficult to bend a toy axle without the added leverage of a portal box.

 

[Toyo Boyo]

When you have some time, wander around this page for a bit. Plenty of good info.

Ramsey Products | Ramsey Silent Chain and Sprocket Solutions

Very interesting - especially this page - talks about using standard profile gear teeth,which would solve the meshing problem mentioned earlier

Ramsey Products | Rampower Silent Chain