There was quite a lot of debate on the Class 22 thread a while back about how one might convert it to EM or P4. I think that the EM gauge fraternity generally decided that the existing wheels could be pulled out slightly on their existing axles, and I hope that this has worked out for them.

 

This wasn't going to work in P4, and the original wheels could only have been used if they were turned down to P4 profiles. Some folk have suggested fitting P4 tyres to the existing Dapol wheels, and good luck to them, too.

 

The issue is that the Dapol Class 22 uses a split axle and associated pick up, as my photos will make clear. This means that the wheel tyres and axles have to be electrically connected. This wasn't a problem for Dapol, obviously, as they have mass produced a decent OO metal wheel for their model, which fits onto stub half-axles, that in turn fit into a central gear assembly.

 

Ultrascale considered doing a 'drop-in' wheel set for a while, but technical issues, which I understand were essentially associated with the fact that they didn't have an all-metal spoked wheel available, meant that they did not proceed with the project, although they do offer a bespoke wheel producing service for P4 modellers, albeit the price is very high and almost as much as the locomotive itself.

 

My method does use Ultrascale wheels, but an existing wheel from their range, namely a 3' 7" 10-spoked Southern tender wheel, which has one less spoke than the Class 22, but is the correct diameter. Each pair of wheels comes with a P4 axle.

 

Here is the Dapol motor bogie, with the keeper plate and one of the OO axles removed (I might add that despite being told how to remove the keeper plate by friends at DRAG, and the fact that it was 'easy', I didn't find it easy at all, and was in constant fear that I was going to break something with the amount of controlled force I was trying to apply at times). In the end, each keeper plate came away intact and without damage. The keeper plates are attached to the bogie side frames, as other photos will show.

 

An OO wheelset, with a pair of Ultrascale P4 tender wheels:

 

 

 

Dismantled OO wheelset:

 

The P4 axles need to be cut into two 10.5mm lengths. If you just cut them in half, there is the risk that the two pieces might meet inside the nylon worm housing and cause a short that you really don't want:

 

After removing the first 10.5mm section, simply remove a further 1mm (or slightly under, to allow for the width of the piercing saw blade).

 

I then spun the rough end I had just cut in an electric drill and filed smooth:

 

 

 

 

 

The next activity involves creating an electrical pathway from the wheel rim, over the nylon wheel centre, to the half axle. I chose to solder a piece of 0.3mm brass wire over the outside front of one of the spokes. The theory was that when the wheel is hidden behind the bogie side frames and painted & weathered, you simply won't notice it, and it saves messing around with the rear of the wheel and the back of the flange.

 

First, I cut groove in the outer end of each half axle and filed a groove big enough for the brass wire (in some cases, I over-did the filing a bit, but it doesn't matter, as the whole thing will be completely hidden afterwards):

 

 

Checking the fit of the 0.3mm brass wire:

 

Returning to the axle and worm, for each wheelset you are left with the central worm component and two half axles, each with a groove filed in the outer end:

 

What happens next was different for the first wheelset as compared with the other three, but the method adopted for the remaining 3 wheelsets was much easier and quicker, so..

 

Measure and mark a point 6mm from the outer end of each half axle and super-glue one half axle per wheel set into the worm assembly:

 

Do NOT glue the other half axle in! The worm assembly is actually hollow right the way through, so if you are not using the split axle method, you could use a complete 2mm diameter axle with the worm assembly mounted centrally, but this would require seperate pick ups and more modifications to the Dapol motor bogies than I felt was necessary.

 

Next is the really barbaric bit. It you love the excellent and well-engineered finish of an Ultrascale wheel set, look away now....

 

To secure the 0.3mm brass wire in the wheel rim, I first cut, then filed, a groove in the rim:

 

A length of 0.3mm brass wire is then put into the groove on the rim, and soldered to the wheel rim. The wire should be pre-trimmed so that the opposite end reaches just as far as the opposite side of the axle hole (ie. reaches from the outer race of the rim, along one spoke, and across the width of the 2mm axle.

 

I would then recommend temporarily mounting each wheel in the other half axle and removing the surplus solder carefully. I filed most of the unwanted material off with a needle file, then mounted the wheel in the electric drill and used two grades of fine wet & dry paper, then a glass fibre pen.

 

The first wheel of the pair is set aside and the second wheel can also have the brass wire soldered to the axle and cleaned up, as per these two photos:

 

 

It's then a matter of assembling the components to make a viable P4 wheelset. These photos were taken of the first wheelset. First on each axle is a 1mm wide brass sleeve, cut from 2mm internal diameter brass tube:

 

Then the Dapol brass bearings are added to each half-axle:

 

Finally, the assembled P4 wheelset:

 

Old and new:

 

NOTE DATED 06-02-23 - MORE PHOTOS TO BE RESTORED IN DUE COURSE

 

What I did for the last three wheelsets, was to assemble the bearing, 1mm brass slieve and wheel to the axle already super-glued to the worm, solder the 0.3mm brass wire from that wheel rim to the steel axle, and then assemble the other side, bringing the whole lot carefully together using a GW Models wheel press and a back-to-back gauge.

 

The first wheelset in the motorbogie:

 

 

With the P4 wheelsets, there's not quite enough room inside the bogie frames, so some material was removed in the area of each wheel with a piercing saw and cleaned up:

 

 

This is the amount of plastic that needs to be removed from each corner of the bogie frame:

 

 

First wheelset sitting inside bogie frame, to check that there's enough room:

 

 

First bogie with both wheelsets fitted and keeper plate/side frames re-attached:

 

 

Second bogie with replacement wheelsets fitted, being test run, prior to it's keeper plate being re-fitted:

 

 

Completed conversion running on 'Callow Lane'. The side skirts and other bits now need to be fitted and the loco weathered: