Ashcroft ATB diff schematic wanted

[henk]

Just bought an Ashcroft ATB diff to go in my front axle but it arrived in pieces.

Is there a schema or movie somewhere to assemble it correctly?

[uninformed]

This might help

 

 

[uninformed]

How the Bellville washers are stacked

 

components laid out

[uninformed]

Pinion orientation 

[Snagger]

The front diff may be a little different to an LT230 centre ATB.  I’d send an email to Ashcroft, or phone them.  It does seem odd to send it out in pieces, especially without instructions, though there may be a good reason for sending it stripped (which should be explained in the instructions).  My suspicion is that you accidentally got a unit that had been returned and stripped for inspection or because of a fault.  Contacting them should clarify, and if necessary, rectify that.

[Bowie69]

Wouldn't be surprised if it was bought used.... OP doesn't suggest it was from Ashcroft.

[uninformed]

4 hours ago, Snagger said:

The front diff may be a little different to an LT230 centre ATB.  I’d send an email to Ashcroft, or phone them.  It does seem odd to send it out in pieces, especially without instructions, though there may be a good reason for sending it stripped (which should be explained in the instructions).  My suspicion is that you accidentally got a unit that had been returned and stripped for inspection or because of a fault.  Contacting them should clarify, and if necessary, rectify that.

What makes you think the axle ATBs would be different internally (other than dimensionally if needed) ?

[Snagger]

I said “may”, not “are”.  The nature of diff ATBs would be that they need to transfer torque in either directions, so would be internally symmetrical, but the centre ATB is generally going to be used mostly in forward drive, so might not have the same arrangement of preload spring washers. Either way, it still seems unlikely the unit was dispatched in a stripped state deliberately, and it reassembling it rather than exchanging it could have warranty issues.

[henk]

As far as I can see I assembled it correctly but did not know what to do with the Belville washer but that has been solved now.

Thanks for the movie and pictures

[uninformed]

8 hours ago, Snagger said:

I said “may”, not “are”.  The nature of diff ATBs would be that they need to transfer torque in either directions, so would be internally symmetrical, but the centre ATB is generally going to be used mostly in forward drive, so might not have the same arrangement of preload spring washers. Either way, it still seems unlikely the unit was dispatched in a stripped state deliberately, and it reassembling it rather than exchanging it could have warranty issues.

The bellville washers are simply retained in between the two side gears. There is no bias to one side or the other. Changing the bellville configuration would only change the amount of preload. Note that the amount of helical angle is the same on both side gears and pinions.

[henk]

Is there a difference in the setup of the 6 ‘satellites’ if the ATB is used in a front or in a rear diff?

[uninformed]

I don’t see why there would be. 
 

what is important is you have the correct 6 pinion gears for their matching side gear. You can NOT mix and match pinion gears and side gears

[Bowie69]

Truetracs are different front and rear. 

[uninformed]

1 hour ago, Bowie69 said:

Truetracs are different front and rear. 

How so?

[Bowie69]

From Mr Ashcroft himself:

 

[uninformed]

So only pre load.  The way the bellville washers are stacked in the LT230 ATB , and as in the photo I posted would be maximum pre load. The only way to get more would be to use different cone/thickness bellvilles. To have less you could face some the same way rather than all opposing. 
 

There is no way to change output bias from side to side. 
 

 

[henk]

I mailed Dave and the answer is that there is no difference between front or rear ATB.

The Belville washers are mounted exactly as on the first picture of uninformed

[Snagger]

The Trutracs have a weaker preload on front diffs and only have the preload working on the direction giving forward drive, so on opposite sides of the scroll gears on a front diff than on a rear.  Ashcroft fit preloads washers on both ends of the scroll gears so the preload works in both directions, and only have one amount of preload, so their units are made to be fitted in either axle.

[uninformed]

What are you calling scroll gears?

The Ashcroft ATB has the bellville washers in between the side gears. The bellvilles are for pre load only. That is, to get the torque bias happening sooner. They do not determine bias. Bias is determined by the helical angle (though apparently you can s fine tune with oil viscosity)

Id be interested to know how they get the TruTrac to torque bias in one direction only for a given hemisphere? In the Ashcroft as I see it, the pinions are forced into the ends of their respective pockets, thus creating friction in the hemisphere. If you rotate it one way the pinions go into one end of pocket, rotate the other and they get forced into the other end of their pocket. Either way both directions creating friction into the hemisphere. 

[Snagger]

The scroll gears are the twelve cylindrical gears which engage on the side gears.  I was under the impression that the preload washers were at their ends, not the side gears, but that may be mistaken.  That would seem more appropriate, given the size shown with six of them between finger and thumb.  Whether they have one at each end of each scroll, or just one end of each sided scroll (given that there are six pairs of offset gears) I don’t know, but I can’t imagine having six very small washers for the two large side gears.

[uninformed]

Here is a photo of how Ashcroft do it. 

the larger scolloped centre section retains the bellville keepers and washers. The keepers are splined to the centre section so they can not rotate. There is a keeper either side of the bellville stack. When the two hemisphere halves are bolted together the side gears compress the keepers flush with the centre section.

 

 

I’ve tried to find detailed pictures etc of the TruTrac but can not. 
 

if they can have little friction on one end of the pinions that might be a way of reducing the torque bias characteristics? 

[Snagger]

Are the Belleville washers in the earlier photo for the LT230 ATB?  That would explain their much smaller size than the axle ATB side gear - that would explain a lot.  Still not sure why there are a pack of six for a single diff; perhaps they need the combined flex of that many.  It seemed logical that with six scroll gears per side, the six washers would be associated with them.  Since their function is to preload the gears so you don’t need left foot braking to initiate torque transfer with a hanging wheel, and Trutracs need that left foot braking, I think they are omitted from the Eaton products.

[uninformed]

All my photos are from the LT230 ATB

[Snagger]

Thanks.

[Daan]

The 3 versus 6 pinions was done by ashcroft to reduce wear, according to their website write up.

This picture does not show anything for pre load:

 

The Dana 44 version has wavey springs between the pinions: