As well as the drawing I do for 3D printing I do a lot of train repairs and DCC installs, particularly sound installs. These can sometimes be a bit tricky and I often have to use other products to make it work. Normally I don’t do reviews of products but recently I found something that worked so well I wanted to share it with you. In this post, I’ll show you what I did to add additional power pickups to a Hornby OO B17 with plastic wheels in the tender.
The B17 has been around for many years and every now and again it gets a facelift as parts are re-tooled and improved. The most recent version is quite fantastic, but the previous one had, in my opinion, one major problem. The tender was the same design from many years before, and still had plastic wheels. The two pictured below are of this version; you can tell by the basic molded coal load in the tender.
This means although the locomotive had been re-tooled to include power pickups on all the drives, it still only had the pickup footprint of an 0-6-0. For DC operation this is often just fine, but DCC, and in particular DCC sound, the decoder required an unbroken power supply and when you factor in dirty track, dirty wheels, and dirty pickups, the 0-6-0 footprint on this loco simply wasn’t working.
Looking under the tender you can see the plastic wheels and even the hole above the third one which allowed a strip of card with a rough surface to hang down. A cam on the last wheel used to rub against the surface and make a kind of chuff effect; this dated back to the 80’s and Hornby called it their ‘Realistic Chuff’ effect.
The red you can see through the hole is a stay alive unit. This locomotive is fitted with a Zimo Sound decoder, but even with the stay alive, if the loco stopped in the wrong place it wouldn’t start again without a push.
The axle for the wheels is simply a bar and the plastic wheels are in two parts. This design has been repeated on many locomotives of early design.
The first problem is to find metal wheels to use. The reason why it’s a problem is just about all the current metal wheels come with much shorter axles with pointed ends. But the old Mainline or Replica Railways (which is now Bachmann) locomotives had metal wheels in their tenders which were the exact same size on long axles. Of course, this does mean sacrificing another loco but six axles from two tenders is enough to do three Hornby locos as I’ve only replaced two wheelsets in each tender. An afterthought would be to see if the plastic wheels fit in the Mainline or Replica Railways tenders?
I found two types of wheelsets in the Mainline/Replica Railways tenders. Some, as with the set on the left, have metal wheels but a plastic axle which doesn’t end in a point. The center and right side wheelset both have metal wheels and a metal axle, electrically isolated, with pointed ends.
As the original Hornby axle measured 26.35mm I wanted to get as close as I could. Any longer will cause binding and make it harder to fit the new wheels.
The set with the plastic axle came in just under and worked perfectly without modification.
The set with the metal axle was ever-so-slightly longer, but this was easily remedied by filing off the points on each end of the axles.
As you can see below both types of wheelsets fitted into the tender and they all rotated very well.
The second issue was how to collect the power from the metal wheels. Over the years I’ve built many homemade pickup systems, normally from strips of brass that rub on the wheels at some point, but it doesn’t always work well and the pressure of a flat strip rubbing on the wheel creates a lot of drag.
Then I discovered DCC concepts’ gold plated bronze wheel wiper sets.
The pack contains 12 sets of wheel pickups, each picking up from both wheels and a pack of screws for mounting.
The actual pickup is a strip of PC board with two folded brass contacts, both gold plated. The contacts have a rounded section to provide a pinpoint contact on the wheel which will reduce drag. Next to the mounting hole are two solder pads, one for each side.
The rear simply has the connection between the pickups and the solder pads.
As you can see below the pickups fit perfectly between the wheels and provide just the right amount of pressure to ensure a great contact with the wheel.
Now it’s time to fit them. With the tender shell removed you can see the metal weight. It will be important to keep this as it’ll ensure the wheels keep good contact with the rails, but it’ll need to come off for now.
The weight was held in place with a few spots of glue.
With the new wheels fitted the pickups can be moved around until the ideal location is found. You need to make sure the rounded part of the pickup is in contact with the middle of the metal wheel flange and not the plastic inner.
Then using a pin vice I drilled a hole, smaller than the screw, in the tender chassis using the hole in the pickup as a guide. The screw will cut into the soft plastic of the chassis.
The pickups can now be fitted in place. I also fitted the wheels again at this point to test everthing worked properly.
The screws were longer than the thickness of the plastic chassis and protruded out of the top. That’s why I removed the weight, and they need to be cut and filed down to refit it.
I refitted the weight using some Black Tack, it’s very sticky and malleable, which is ideal for this job.
The solder pad can now be linked with wire. If you have a large soldering iron you may want to solder the wires on before the pickups are fitted to prevent caching the chassis with the iron as it will melt very quickly.
Lastly, I solder on two wires to connect back to the main locomotive pickup points. It’s important to ensure you match the tender wheels from the correct side with the loco wheels or it will simply short out.
With the tender reassembled and all the wires connected it was time to test the loco, and it ran very well. The best test was to raise the loco off the rails, so it isn’t picking up any power and see if the tender pickups worked on their own, which they did, as you can see in the short video below.
I could’ve fitted three sets to the tender, but after testing two proved to be plenty, and both the B17 locomotives from the first picture are now running equally as well as the latest version of this locomotive, which comes with factory fitted tender pickups.
These pickups from DCC Concepts are very good and, I think, very well priced because you get 12 in a pack. I’ll certainly be using them again. I just hope they bring this product out for N Scale. You can get the pickups direct from DCC concepts or at a stockist such as Model Railway Solutions in Poole.
Next week I’ll share with you some of the 3D printed parts which arrived last week.