Portal axle box using chain (1 Viewer)

[bjowett]

I've been throwing around the idea of a portal axle box using a silent chain. Silent hyvo type chains are used for all sorts of things, most are probably farmiliar with its' use in transfer cases. My main concerns are shock loading and strength. I've discussed this use with one company, but they calculate for industrial use only, which is 8 times breaking strength. That would produce a silly wide chain, not at all practical.... does anyone on Mud have any experience using these chains in other applications? Snowmobiles use a Hyvo chain and they take a serious pounding. Some benefits would be various ratios, and quiet operation.

 

[rusty_tlc]

No first hand experience but everything I've read on t-cases sez;
chains = bad
gears = good.

 

[liljlandon]

Ive got a AutoCAD file ive been pounding on for a while to make a Portal Box, and chains have crossed my mind. I believe it would be based on weight of the vehicle. For example, a mini with the 22r/5spd/duals whatever would be plenty light enough to go with a chain, while a cruiser would be much to large and heavy IMO.

Ive got the rear all done on CAD, besides the exact diameter of the axle shaft and somehow making the gears, im rather new to CAD so im unfamiliar on how to make them.

The front is what im having difficulty with. My plan is to market my portal box's as a do-it-yourself kit that would be MUCH cheaper than the others. They would be a weld/bolt in kit for mini truck axles, as its all i have for a donor.

Im not sure the knuckle would be strong enough to support a portal sytle box with ~5" of drop. Any input?

 

[Toyo Boyo]

No first hand experience but everything I've read on t-cases sez;
chains = bad
gears = good.

I'm afraid I'm going to have to disagree with that statement sir!

I used to work in the project engineering dept. at a Borg Warner plant over here - we made the transfer case for the Range Rover. The Morse TEC chains used in that app (Brog Warner 1361 and 4462 cases) were massively over specced for their torque requirements. We never ever had a chain fail. They were used by RR due to their reliability and also because they are so much quieter than meshed gears. At the time they were not used on the Discovery (LR LT230 case?) to maintain the premium feel of the Range Rover.

The chains have been used for engine valve trains, autobox power transfer and of course many transfer cases.

I think using them in a portal axle would be an excellent idea.

Much of the internals of the 1361 case was also used by Borg's in the Ford Explorer case so you'll have lots of those laying around in junk yards if you want to get hold of some cheap. You would be able to use the mating cogs as well as the chain. The cogs are machined to a special profile that mates neatly with the inner profile of the chain. You'll also have a ready supply of the planetary reduction hub sets as well.

See here for some more info

MORSE TEC CHAIN - Google Search

borg warner 1361 - Google Search

borg warner 4462 - Google Search

I'll see if I can get hold of more info over the next couple of days. The plant they made most of this stuff was in Muncie, Indiana.

Here's an exploded view of the 4462

http://www.automaticchoice.com/Catalogue/tb_bw_4462.pdf

 

[rusty_tlc]

I'm afraid I'm going to have to disagree with that statement sir!

...

No problem, like I said I have no first hand knowledge on the topic. Just what I've read.

 

[Toyo Boyo]

No problem, like I said I have no first hand knowledge on the topic. Just what I've read.

Hey no worries!

This has really got me on a mission.

I've spent the last 3 hours sketching out ideas and searching the net.

I'll post up my crap tomorrow.

IDEA - if you included reduction hubs could you get a crawl ratio - but without the need for a second transfer case (for serious buggies only (don't think it could be engineered for the road))

 

[liljlandon]

IDEA - if you included reduction hubs could you get a crawl ratio - but without the need for a second transfer case (for serious buggies only (don't think it could be engineered for the road))

Yep, a reduction hub. You could do all kinds of different reductions,

for instance, in the one im pounding around, i have set it to where the reduction in the hub would take you from 4.10:1 to 16:1 while maintaining the stock 3rd members.

Its like killing two birds with one stone, stock 3rds are available anywhere, the reduction is in the box, thusly youll rarely see a 3rd go due to a tire size or power related injury. The box ive got drawn up splits in half with a few bolts, and with removal of a snap ring you can change the gears in the box. Simple, and easy.

EDIT: for the road, a slight reduction would be beneficial. You could take and reduce it 1.46:1 and get an over all 6:1 gear ratio using a 4.10 3rd, so in my world it would mean running 37's and maintaining the stock speedo config and maybe pulling the same RPMs at speed as it would with stock tires.

 

[Arya Ebrahimi]

People stretch/break chains in t-cases as is. Do you really think they will hold up to the additional reduction of the ring and pinion loading them up with more torque?

That's a serious question, not a smartass comment.

 

[Mark W]

There is more torque reaching the chain in this location than inthe T/C. BUT... there is less load and less resistance to movement (one tire to bust free of traction, not four).

I think it is probably a very workable approach. Without having spent any real time pondering it myself.


My concerns would be the strenght of any knuckle/kingpin bearings and the complication of the front end fitment.


Mark...

 

[Toyo Boyo]

People stretch/break chains in t-cases as is. Do you really think they will hold up to the additional reduction of the ring and pinion loading them up with more torque?

That's a serious question, not a smartass comment.

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

 

[bjowett]

The chain and sprockets/cogs are available off the shelf in many sizes. The inner diameter of the cogs is cut for the application, they list min and max dimensions of what can be cut into the bore for the various pieces. Some of these companies produce chains that run continuously under thousands of HP.

Funny you worked for Morse Tec. The chain in the 2007 and up Tundra Transfer Case has a Morse Tec Japan Chain. The 08 200 Series Cruiser probably uses this chain, too. Being a full time case vs the Tundra part time unit, they may have spec'd a more stout chain. Anyway, in the Tundra it's a .43 pitch, 1.5" wide chain is not a large chain. The case is rated by Aisin for an input 550ft/lbs of Torque. Multiply that by the 2.618 low range and this chain has the potential to see 1500 ft/lbs. So if we get into larger pitches and widths, the strength could be there... duty cycle is very imortant, as well as multiple other items...

The knuckles are of concern...

 

[Toyo Boyo]

I worked for Borg Warner, they own Morse TEC and use their chains in the transfer cases they make - keep it in the family!!!

The later Range Rover case (4462) was rated to 1650ft/lbs - so very similar numbers there.

How much torque would you see at a given hub? And what would be worse case scenario? Locked diffs, one wheel with excellent traction? I dunno lol

Agree on the knuckle being the weak point - the rear would be much easier to engineer.

Very interesting though, quite thought provoking

 

[liljlandon]

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

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.

 

[Tools R Us]

My experience with chain drive transfers isn't so much breakage, but they tend to stretch, become sloppy when wheeled. They require more slack/backlash than gears? How well would they handle the constant pounding of on/off the throttle when at the wheel?

The worst case scenario would be a full throttle climb, fully locked, all 4 tires bounced off the ground and landing on high traction rock on 1 spinning tire? It would need to be able to withstand this multiple times without noticeable stretch, etc.

On the gear side, I have done some "old American iron" machine tool repair. A couple of times replacement gears weren't available, asked around and was referred to Boston Gear. Both times they had gears with the same spec in stock, when they arrived they looked the same as the original, so were probably the OEM supplier. At the time called and bought direct, good tech and reasonable prices. That was ~10yrs ago so not sure if they still deal with the public. The catalog is available for download.

http://www.bostongear.com/litportal/pdfs/P-1482 ALL PAGESsm.pdf

 

[Jetboy]

I'd say a max torque, and minimum design spec would be somewhere in the range of 10,000 ft lbs. That would be slightly stronger than a longfield. I think that's a good measure of what seems to be enough to handle most toyota applications. At least in the front. The rear could be stronger. Of course with only 37" tires you could go a bit less at the shaft end and figure 10k lbs at the final drive gear. Then the tension on the chain is a function of the radius of the drive gear. So the bigger the final drive gear the smaller chain you could get by with. At any rate I'd guess that the gears would have to be smaller than those in the transfer case. So I'd plan on a chain on the order of 10 times the strength of a transfer case version. My guess is that using affordable materials, the chain is going to be too wide to fit inside any reasonably sized gear box.

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

 

[bjowett]

Good guesses! I just got done figuring it all out.... The breaking load on the t-case chain is in the established 8:1 range. 12000lb break/8 = 1500! So it does appear that automotive applications use the same standards as industrial type stuff. The chain would have too be 16" wide to meet this standard. I'm begining to think this idea may be beat.

Thanks for the gear info!

 

[rusty_tlc]

AFAIK gear reduction in a portal axle is the norm.

 

[liljlandon]

AFAIK gear reduction in a portal axle is the norm.

I would suppose it would be standard, wouldn't running a 1:1 in the portal just consume more power?

There may just be to much math in this for me to comprehend. Wonderful.

 

[rusty_tlc]

I would suppose it would be standard, wouldn't running a 1:1 in the portal just consume more power?

There may just be to much math in this for me to comprehend. Wonderful.

Why? At 1:1 the only power loss would be in the gear/bearing friction.
A reduction gearing would result in power loss, ie more revolutions to cover the same amount of ground.

 

[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

16'' wide chain? That would be some housing to hang off the end of an axle.

The reduction gears were mentioned as a possible way of getting low revs without the need for a second transfer case - just an idea thrown out there. Massively complicates the potential design though