Thread: Detroit Locker Failure

Does it matter - the point was to check the splines on the flanges on the hubs where the axle drives the wheels.

The issue has now been over taken by events as the locker is removed and the cause found.

Move on.

Originally Posted by Red90

No. It is a full floating axle. The hub is a unit bearing.

Stop and think if there was a drive flange instead of the hub being internally splined. It would work exactly the same way.

Its just a 2 piece semi floating axle. As said, the axle isn't even floating. A floating axle is an axle that is loose which is what float is, albeit the axle float is retained or limited - you can measure the end float if you like. A d2 axle doesn't have float because it is bolted flange and presses the bearing. The load points aren't what define what a floating axle is, it is whether the axle floats within the system. The D2 axles doesn't do this at the hub end which is why it is called a semi-float - semi float because it floats at the diff end. The only difference between a D2 semifloat and a textbook semifloat is the bearing runs on the flange in the Disco2 and not the shaft which is a far better setup as it doesn't bend the axle, the axle just retains the hub, but if you snap the axle between the halfshaft flange and the wheel flange then it all comes apart - unlike in a full float setup where the axle carrys no load apart from torque and the hub is retained on a spindle and the axle is free to float between its captive limits.

Look, I'm really not invested in what people call it, it makes no difference to either of us - the axle just isn't floating in the system, there is no way that it can actually float.



Actually wiki has a good explanation of floating/semi-floating because it identifies as an engineering text.
Axle - Wikipedia

A full-floating axle carries the vehicle's weight on the axle casing, not the half-shafts; they serve only to transmit torque from the differential to the wheels. They "float" inside an assembly that carries the vehicle's weight. Thus the only stress it must endure is torque (not lateral bending force). Full-floating axle shafts are retained by a flange bolted to the hub, while the hub and bearings are retained on the spindle by a large nut. In contrast, a semi-floating design carries the weight of the vehicle on the axle shaft itself; there is a single bearing at the end of the axle housing that carries the load from the axle and that the axle rotates through. To be "semi-floating" the axle shafts must be able to "float" in the housing, bearings and seals, and not subject to axial "thrust" and/or bearing preload. Needle bearings and separate lip seals are used in semi-floating axles with axle retained in the housing at their inner ends typically with "c-clips" which are 3/4-round hardened washers that slide into grooves machined at the inner end of the shafts and retained in/by recesses in the differential carrier side gears which are themselves retained by the differential pinion gear or "spider gear" shaft. A true semi-floating axle assembly places no side loads on the axle housing tubes or axle shafts.


Axles that are pressed into ball or tapered roller bearings which are in turn retained in/on the axle housings with flanges, bolts, and nuts do not "float" and place axial loads on the bearings, housings, and only a short section of the shaft itself that also carries all radial loads.


The full-floating design is typically used in most 3/4- and 1-ton light trucks, medium-duty trucks, and heavy-duty trucks. The overall assembly can carry more weight than a semi-floating or non-floating axle assembly because the hubs have two bearings riding on a fixed spindle. A full-floating axle can be identified by a protruding hub to which the axle shaft flange is bolted.


The semi-floating axle setup is commonly used on half-ton and lighter 4x4 trucks in the rear. This setup allows the axle shaft to be the means of propulsion, and also support the weight of the vehicle. The main difference between the full- and semi-floating axle setups is the number of bearings. The semi-floating axle features only one bearing, while the full-floating assembly has bearings on both the inside and outside of the wheel hub. The other difference is axle removal. To remove the semi-floating axle, the wheel must be removed first; if such an axle breaks, the wheel is most likely to come off the vehicle. The semi-floating design is found under most 1/2-ton and lighter trucks, as well as in SUVs and rear-wheel-drive passenger cars, usually being smaller or less expensive models.


A benefit of a full-floating axle is that even if an axle shaft (used to transmit torque or power) breaks, the wheel will not come off, preventing serious accidents.

Originally Posted by DiscoDB

It’s more like a three-quarter floating axle but with an inverted double bearing wheel hub.

It uses the pronouns they/them.

I've never heard of that term but it certainly picked up whats going on!

they/them is certainly better than zim/zer!

Originally Posted by 101RRS

Does it matter - the point was to check the splines on the flanges on the hubs where the axle drives the wheels.

The issue has now been over taken by events as the locker is removed and the cause found.

Move on.

Just a thought provoking discussion.

I’m a mechanical engineer. It is a full floating axle.

Originally Posted by Red90

I’m a mechanical engineer. It is a full floating axle.

Semi-float

Originally Posted by Red90

No. It is a full floating axle. The hub is a unit bearing.

Stop and think if there was a drive flange instead of the hub being internally splined. It would work exactly the same way.

Agree that the bearing unit has the attributes of a fully floating axle. This is not what determines if the axle is fully floating.

As Slunnie has pointed out, fully floating refers to if both ends of the axle shafts are free to slide in/out at both the diff end, and drive flange end. The axle drive shaft literally are fully floating at both ends and as such do not carry any side load. The axle shafts carry no other load other than torsional load.

This also allows the axle shafts to be removed in situ without interfering with the wheel bearings, and can even be removed with the wheels still fitted.

The D2 axle shafts can only float at one end, and are used to clamp the bearing hub assembly to the axle casing at the drive flange end, held in place by a 490Nm nut. This fixes one end of the drive shaft to the bearing assembly and hence can not be considered fully floating as it adds lateral (side) load at the ends of the drive shafts.

Fully floating axles the bearing assembly is held in place by retaining nuts on the axle casing, keeping the axle shafts stress free from any lateral (side) forces. The shaft carries no bearing load at all and can have end float at both ends. The axle shafts are essentially fully floating within the axle casing and are not used to retain the bearing assembly. As such, fully floating axle shafts only see torsional load.

Three-quarter floating axles the bearing assembly is also located between the hub and axle casing, but held in place by the axle shaft and hence the axle shaft also carries side loads. Like a fully floating axle, the vehicle weight is transferred direct to the axle casing (not the shaft), but like a semi-floating axle, the axle shaft is fixed at one end and is critical to holding the bearing assembly in place. Three-quarter floating axle shafts see torsional load, and side load (at the ends only).

Semi-floating axles the wheel flange hub and axle shaft are one unit, can not be separated like a three-quarter floating axle, and the axle shaft carries the vehicle weight as the bearings are mounted direct to the axle shaft. Like a three-quarter floating axle, semi-floating shafts only float at one end. A semi-floating axle shaft sees torsional load, side load, and bending loads.

By the definition of axles its a full floating axle, untill its not...

Originally Posted by DiscoDB

It’s more like a three-quarter floating axle but with an inverted double bearing wheel hub.

It has some attributes of both the semi-floating axle and fully floating axle, but it is not truly either.



It uses the pronouns they/them.

If you have a look at the picture above theres no bearing directly mounted and secured to the axle, the axle does nothing to support the weight of the vehicle, and the axle does nothing to longitudinally locate the hub... except it does.

BUT

if you replaced the axle with a stub like the one thats broken off in the picture below

Originally Posted by Slunnie

They’re pretty easy on the splines and don’t really wear them because the clamping force on the axle from the semi floating setup probably stops most of the movement. If anything they just snap beside the flange which is on the axle.

the hub is now correctly located.


Heres the fun.

IF you snap the half shaft like the picture above, it works like a fully floating axle the wheel stays where its wanted

If you snap it at the splines, its a 3/4 floating axle, and eventually the bearing assembly works its way out then you loose the wheel and hub, of course the whole lots retained by the brake caliper which amazingly will keep the whole lot in place until the customer gets the vehicle from somewhere south of brisbane central out to ipswich