I am currently in the early stages of design of a brass steam locomotive (4-6-0). I am using the MR articles from OCT97-May98 as a guide for this project. Unfortunately, the article only discusses split pick up between the engine and tender. I would like to have pickup from both rails, but am unsure how to accomplish this in the locomotive. The tender should be easier.
I get the wheel wipers idea, but how do I isolate the cylinders from the valve gear? Should I 3D print them and make a "hybrid" model?
I think the best way would be to use drivers that have the 'tire' (or rim if you will) isolated from the wheel itself. Many comercially produced locomotives use that sort of system. You would have to make sure that the rim cannot come in contact with the chassis or the running gear.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
hon30critter I think the best way would be to use drivers that have the 'tire' (or rim if you will) isolated from the wheel itself. Many comercially produced locomotives use that sort of system. You would have to make sure that the rim cannot come in contact with the chassis or the running gear. Dave
Thanks again Dave
It will depend on the drivers that I can find. The only ones that look even close (and they are a bit off crescent counterweights vice straight) are from Greenway in PA.
I do lead a sheltered life, but I haven't seen, yet, any steam engine drivers that weren't insulated between the tire and the wheel hub. Well, there's certainly an exception: all-plastic hubs. But I think Greenway goes the traditional route.
Years ago, I converted a Hobbytown drive to 8-wheel pickup by attaching wiper assemblies to the bottom of the trucks. It worked nicely.
Now, I am again working on a Hobbytown drive. This time, I am using a "keep alive" (along with the implied DCC and sound). IF there is still a problem, I will add the wipers.
Ed
7j43kI haven't seen, yet, any steam engine drivers that weren't insulated between the tire and the wheel hub.
Hi Ed,
I thought that was the case but I wasn't sure if there were other ways of doing it.
Dave,
Other ways do come to mind:
There's the plastic wheel hub I mentioned. I think my old Rivarossi Dockside had this, with wipers on each side against the tires. I DO have the impression Rivarossi did this on other locos, too.
One could insulate at the axle. I've not seen it. I would recommend against it because of weakening the axle/wheel connection. And, of course, the rods, valve gear, etc become "live". This would likely be the worst choice.
And maybe someone has done a steam version of the diesel setup: metal wheels and half axles with a plastic common axle. Maybe some Athearn engine, like their 0-4-2T. Maybe. Again, though, the designer has to deal with keeping + from - throughout.
One thing I've seen, often as an add-on, it a small piece of plastic mounted to the bottom plate, holding some phosphor-bronze contacts. So one side of the loco comes through the frame like usual, and you get pickup from the other side through the insualted pickup rubbing the back of the flange area on the other side.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
To be honest I just assumed that the entire wheel was hot. Never imagined that there was an insulator between the tire and the wheel center. It makes sense that it would not be.
The Greenway drivers are insulated on one side, pretty-much the same as most all-metal driver sets have been for years.For making all-wheel pick-up, there's no need to worry about insulating the cylinders from the frame or anything else, as the current pick-up on the insulated drivers is itself isolated from the frame and connects only to the motor and could be, if you've also installed all-wheel pick-up on the tender, connected to its counterpart pick-ups on the tender, too. That simply creates a back-up path should one of those connections to the motor fail.
These photos are of a couple of brass 0-8-0s to which I added all-wheel pick-up for a friend...
These were the first ones which I did, and I used modified Kadee centering springs as the wheel wipers - they ride only against the back face of the driver's tire, since it's insulated from the driver's centre. The springs are simply soldered to copper-clad circuit board which is cemented to the loco's coverplate using contact cement, and wires added to connect to one of the motor contacts.
Later installations utilise .020" phosphor bronze wire for the wipers, as the heavier wire allows the pressure against the wheel to be adjusted. Because that pressure can be greater than that afforded by the modified coupler springs, I put wipers on the non-insulated wheels, too. Obviously, the copper cladding needs to be removed from the middle of the board to keep the two sides electrically isolated.By having wipers with roughly equal tension on them, they'll maintain better contact when the loco is going around a curve or through a turnout.
Wipers on the tender trucks are similar, and newer installations now use the phosphor bronze wire and act on all wheels of the tender...
I use mini-plugs to get the power from the tender to the locomotive...
For a brass locomotive, you can use double-sided copper-clad circuit board, and solder it to the bottom of the driver's coverplate.
I've been searching for a photo of the wire wipers, but can't seem to locate any. However, I do have a loco that I've done for another friend which has that system, and I'll take a photo of it and post it here in a few minutes (I don't want to leave this message sitting unposted while I make the photo, since the site seems to erase it if it sits too long unattended.)
Two minutes to take the photos, two minutes to put them into photobucket, the rest of the elapsed time trying to find where the heck photobucket hid them.
This locomotive's drivers and the front tender trucks can be bouncing along the ties, but as long as the rear truck of the tender is tracking properly, she'll carry on.
Wayne
Wayne's methos is pretty much what I was trying to say, although I've seen the wipers mounted to a piece of plastic instead of a piece of copper clad like Wayne did. If you do use copper clad, check it with a meter on continuity to make sure the two sides are insulated from one another. They're supposed to be, otherwise 2-sides PC board layouts would never work, but depending on how you cut off the small piece to use to mount the wipers, a sliver of copper could make contact from one side to the other. Talk about a frustrating problem to track down. Happens when handlaying track with PC board ties, too.
I've re-taken the photo of the locomotive's underside, and with a little less glare, the insulating gap in the copper cladding is more readily seen:
I use a utility knife to scribe two roughly parallel lines in the copper, re-scribing a few times until it's cut through, then use the tip of the blade to lift one end of the strip so that it can be removed.
Here is a similar installation to doctorwaynes except in this case one side of the locomotive was already picking up power. This is an older installation using hardened brass wipers. They work fine but you have to be very careful about the amount of sideways pressure they exert on the drivers. Too much pressure pushes the drivers all to one side which may interfere with tracking in a curve. I used epoxy to mount the copper clad boards (now painted black). I have since gone to .020" phosphor bronze like Wayne:
Something you might want to keep in mind when setting up the tender to locomotive wiring is where exactly to mount the connectors. In this case they fit quite nicely into the back plate of the locomotive. Even the rivets lined up! The advantage to having the plugs a bit higher than they might otherwise be is that there is much less possibility of the wiring snagging on turnout points etc.
This is DCC with the decoder in the tender, hence the number of connections. One socket is painted white to prevent the plugs from being plugged into the wrong sides.
doctorwayne I've re-taken the photo of the locomotive's underside, and with a little less glare, the insulating gap in the copper cladding is more readily seen: I use a utility knife to scribe two roughly parallel lines in the copper, re-scribing a few times until it's cut through, then use the tip of the blade to lift one end of the strip so that it can be removed. Wayne
Obviously you need that gap carved in, but I was acturally referring to front to back, unless your copper clad is one sided. Most you get any more is double sides, and the punching or cutting process can get a sliver of copper touching front to back along the cut edge unless you take care to also sand each edge. The adhesive to glue it to the bottom of the loco frame MIGHT not be conductive, but there's always a chance a bit of the copper touches the metal directly. It can be particualrly tricky when you KNOW you've cut the gap in the top side, and you cna examine it under magnification and see there is no stray copper connecting the two sides of the gap, yet you still get continuity across it - via the underside of the board. Rare, but it can happen. Simply sanding the edges after cutting a piece out of a larger sheet usually takes care of it, so that bare board is visible between the copper layers all around the edges.
Thank you Randy, Dave and Wayne.