Thread: Portals

Originally Posted by djam1

Pretty sure I will need a flame suit for this but I don't think Portals are particularly practical in a tourer.
Years ago I was involved with running Unimogs as tour buses and we always had issues with the bull gears in the portals burning out on the highway.
While better lubricants helped the issue never really went away and this became a profoundly expensive part of the operation of these vehicles.
Fine for a weekender but a thousand ks a day with road temps up over 60 degrees didn't do them any good.

Exactly the opposite to the problem I am having, great on the open road, desert, mud, sand type touring conditions. Useless as a weekender unless you take a flatbed with you…….

Originally Posted by Ancient Mariner

Any chance of an exploded drawing?

Thanks AM

This is the Tibus one

http://www.killeraxles.com/2010.120.ex-1.pdf

Maxi-Drive portals had the case made from SG cast iron. The input and output gears are both supported on taper roller bearings, the twin idler gears are supported by needle roller bearings.

Can someone paint me a picture in words, how the tibus portals and disco 2 axles are semi float. I get they use a unit bearing, funny thing is it seems the yanks call these full floating. When I saw these unit bearings only a month ago, I couldnt figure out what is going on???

I see the unit bearing is running on the outside of the hub, and the stub axle is a spline fit into this hub. Is it that the hub is loaded inside the bearing that it flexs the stub shaft, rather than on the LR design where the hub is located over the bearings on the stub axle and loads that rather than the shaft?

Originally Posted by uninformed

Maxi-Drive portals had the case made from SG cast iron. The input and output gears are both supported on taper roller bearings, the twin idler gears are supported by needle roller bearings.

Can someone paint me a picture in words, how the tibus portals and disco 2 axles are semi float. I get they use a unit bearing, funny thing is it seems the yanks call these full floating. When I saw these unit bearings only a month ago, I couldnt figure out what is going on???

I see the unit bearing is running on the outside of the hub, and the stub axle is a spline fit into this hub. Is it that the hub is loaded inside the bearing that it flexs the stub shaft, rather than on the LR design where the hub is located over the bearings on the stub axle and loads that rather than the shaft?

In a full-float axle the half shaft or stub shaft only sees the torque. The weight and dynamic loads associated with the weight are carried by the spindle.

With a semi-float axle all of the loads have to be carried by the half shaft or stub shaft.

You would have noticed in your Defender, with full-float axles, the wheel bearings are mounted on a spindle. You could remove the rear half shafts and still drive it (with the centre diff locked). In a semi-float axle if the half shaft was removed there is nothing remaining to support the wheel.

Disco 2 can be classed as full floating to a degree, as the vehicle can be supported and rolled along WITHOUT a halfshaft in place, and the halfshaft is not subject to any bending moment, only torque.

BUT, the axle cannot be withdrawn from the vehicle without firstly removing the hub, so it is kind of different but same scenario.

Chook, looking at those pics, there are all sorts of reasons why that outer axle broke, materials choice, stress raisers, et al.




JC

A little bit more about the tibus portals

1. The Output Shaft - the bottom (rear) sits into a bearing race in the back of the portal, the gear is obviously driven by the idler gears. Directly next to the gear is a seal and then the spline sits into the flange. The thread is the hub nut and washer which holds the flange onto the output shaft.



2. The Wheel Bearing Assembly - This attaches to the portal and houses the wheel bearings and ABS sensor, the flange sits through this





3. The flange assembly, the threaded holes in this receive the bolts which travel through the brake disc holding the wheel stud plate on.





Here you can see the wheel stud plate and disk in place bolted into the flange



When all together they look somewhat like this, note I haven't pushed them together as I dont want to stuff up what little spares I have.



My theory is that if the output shaft snaps as per the previous photos then there is technically nothing that holds the flange to the portal. Whilst the flange travels through, and is supported by the wheel bearing assembly, without the hub nut securing it to the output shaft there is nothing stopping it travelling east.

Originally Posted by Bush65

In a full-float axle the half shaft or stub shaft only sees the torque and the weight and dynamic loads associated with the weight are carried by the spindle.

With a semi-float axle all of the loads have to be carried by the half shaft or stub shaft.

You would have noticed in your Defender, with full-float axles, the wheel bearings are mounted on a spindle. You could remove the rear half shafts and still drive it (with the centre diff locked). In a semi-float axle if the half shaft was removed there is nothing remaining to support the wheel.

John, the way Im seeing this particular set up and im guessing its the same as the Disco 2, that the vehcile could still be rolled around without the axle/stub shaft. The unit bearing is bolted to the portal (or axle housing end), the hub runs inside these bearings. It is only the shaft that retains it from moving in or out. So are they still considered a full floating set up?

Originally Posted by uninformed

Originally Posted by Bush65

In a full-float axle the half shaft or stub shaft only sees the torque. The weight and dynamic loads associated with the weight are carried by the spindle.

With a semi-float axle all of the loads have to be carried by the half shaft or stub shaft.

You would have noticed in your Defender, with full-float axles, the wheel bearings are mounted on a spindle. You could remove the rear half shafts and still drive it (with the centre diff locked). In a semi-float axle if the half shaft was removed there is nothing remaining to support the wheel.

John, the way Im seeing this particular set up and im guessing its the same as the Disco 2, that the vehcile could still be rolled around without the axle/stub shaft. The unit bearing is bolted to the portal (or axle housing end), the hub runs inside these bearings. It is only the shaft that retains it from moving in or out. So are they still considered a full floating set up?

You are correct.

In the past I have seen wheels come of cars when their semi-float rear axles broke (some model cars were noted for that). It can be very worrying and it remains a vivid memory that lights up at the mention of semi-float axles.

Now I have seen those pics I wouldn't argue with anyone who wants to say they are, or that they are not, full floating, particularly if they qualify their remarks.

The great advantage of full floating axles that they only transmit torque and are not subjected to bending or shear loads. Thus they are less likely to break.

However many Land Rover owners (there are some that will deny it or blame the driver/owner) know that full float half shafts and stub axles can and do break (otherwise there would be no market for upgraded replacements) and it is reassuring for those with "proper" full float axles that their wheels will remain perfectly safe and fully functional.

Unit bearings are becoming more widely used and I would not be surprised in the least if the Defender replacement has them. They reduce costs for manufactures of vehicles, but are considerably more expensive for vehicle owners to replace than normal wheel bearings.