Updated: 28 December 2003
The Bachmann Sulzer locos provide an ideal beginners
project in Protofour as they can be converted with a simple exchange of
wheelsets. Drop in wheelsets are available completely assembled from Ultrascale
but it is more economical to use the conversion sets available from Alan
Gibson which re-use the original axle gears and bearings but need a few
minutes more work. (Note that this procedure covers the new model class 44, the
older class 46 is best converted using the Ultrascale drop in sets as they have
non-standard axles).
Click on any thumbnail for a larger picture. |
|
1. Class 24/25 fixing screws
|
Although it is possible to change the wheels without
removing the shell it is easier to unclip the bogie frames if the bogies are
first released from the chassis. To do this the bodyshell must first be removed.
For the 24/25 there are 4 screws underneath on either side of the fuel tanks
which must be removed, see photo for the location. Once these screws are out the
bodyshell will pull off taking care to ease the clips located above the buffer
beam at each end. For the class 44 there are only two screws as shown in the second photo, and in this case no clips so the shell lifts straight off once the screws are out. All these screws are of the crosshead pattern but I have not found the crosshead drivers to fit well and have used a jewellers flat blade driver with more success. Once the shell is off bogies can be released by removal of the pivot screw shown in photo 3. I suggest removing only one bogie at a time. There is no need to remove the wires from the circuit board as there is enough slck to work on the bogie. (Note: if the bogies are removed from the 44 its a bit of a juggle to get the drive shaft back into place, if this worries you leave the bogie in place, it just needs a bit more care to unclip the bogie frame. The outer cosmetic frames are fixed to the inner gearbox by a clip at each end. For the 24/25 I have found it easiest to unclip from the outer end using a small screwdriver. For the 44 the pony truck should first be unscrewed as the screw helps retain the outer end of the cosmetic frame, then unclip from the inner end. With the bogies fully rotated this can be done fairly easily without releasing the bogie. When the cosmetic frame is released the inner idler wheels will likely drop out along with their bearing saddle and spring, keep the bearing saddle and spring safe for use when re-assembling.
|
5. Original wheelset |
6. Removing wheel |
The first action is to recover the gears and bearings from the Bachmann wheelsets. The bearings are a clip fit into the gearbox and a little pressure from the fingers will pop the wheelsets out, or you can apply a bit of leverage with a screwdriver between bearing and gear, whichever way be careful not to disturb the pick ups. The wheels and bearings can then be removed and the gear pressed off the axle, the axles are knurled under the gears so press them straight off without twisting. I use an NWSL wheel puller but you can use your favourite method. Keep gears and bearings safe for re-use.
|
18. Idler axle with sleeve |
For the 44 there are still the idler wheelsets to deal
with. The inner idlers on the original have 3mm diameter axles, the AG
replacements are 2mm diameter. To correct this cut a 17mm sleeve from brass
tube, 3mm outside diameter and 2mm bore and assemble the wheelset with this
sleeve between the wheels. For this wheelset the axle should be reduced to 22mm
length but should not be knurled. For the pony truck a 3ft diameter disc wheelset is required, eg Alan Gibson part G4S09. The axle should be reduced to 22mm as above and the wheelset assembled to the pony truck with two 3mm spacers made of the same 3mm brass tube. This done everything can be put back together.
|
Note: If you have heavy loads to pull the tractive effort
of the 44 is a bit disappointing, distinctly inferior to either the 24/25
or the earlier version 46. This appears to be a direct result of the stronger springs on the idler axles and pony trucks, if you need more pull you can try reducing the spring pressures but bear in mind this will probably be at the expense of trackholding and it is easy to overdo it. |
Copyright Keith Norgrove.
Last revised: December 28, 2003