Your thoughts: wheel wipers.

Ladies and gentlemen:
I want to know everybody's deepest and darkest thoughts on the subject of wheel wipers for electrical pickup.
Now, I have this view that they are a necessary evil. It's not their appearance that I mind but their lack of functionality, at least in my HO steam engines. The only ones I have that really work well are the pivoted shoes on a Mantua Booster, with a separate spring to hold them against the wheel tread, but this is quite a collection of parts, and doesn't fit in engines with smaller axle spacing.
What I want to find out is what design works the best. Is there any arrangement of pickup wiper that functions as well or almost as well as picking up current through the axle bearings?
I have used Rivarossis with wire wipers that hook over the flanges, Life-Like tank engines with plain metal strips, Model Power engines with wheel-back wipers, and none of them seem to work really well.
Cordially yours, Gerard P. President, the electrically incompetent Sparta Railroad.
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snipped-for-privacy@gannon.edu wrote:

I build locos with phosphor bronze spring wire pickups bearing on the back of the flange. All that's required is a post mid -way between axles for the spring wire to pivot on so that the tensioning of the wiper ends is equal and constant. (2mm machine screw in a plastic tube through solid chassis. Short 2mm screw into PC board under chassis on others) Magib in Britain make a 'brush and spring in top-hat tube' collector that rubs on the back of the flange for sheet brass frames. It's a lovely bit of engineering, is almost invisible and provides wheel sideplay centering - but, it does clog up eventually.
Regards, Greg.P.
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Gerard
I do the same as Greg proctor and add wipers to backs of the flanges. I only use a .3mm brass wire as I didn't have any Phorous bronze at the time. All my Athearn, and Proto2000 have been done the same way.
I was making up a small web page about current collection since it is so important for good DCC running. My camera batteries have died but here is the start of the page. http://www.wave.co.nz/~lakewood/Pickups/Pickups.htm
Nigel
-- Western Pacific Model Railroad http://www.wave.co.nz/~lakewood/MyWP.htm

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snipped-for-privacy@gannon.edu wrote:

I have a couple of brass models of some tank locos. Wipers are an obvious necessity on one side due to the lack of a tender. Yeah, there's some operational issues with them.
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Rick Jones
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There's many ways to skin this caat! I prefer to use shoes which bear againt the track. The thing that is nice about these is that they avoid the whole rolling contact thing with the wheel so the wheel can get dirty and not matter as to whether the electrical contact is made. Downside is that the shoes can pick at badly laid track and are apparent in looking at the loco as the shoes are quite visible between drivers. Next be6ter is the contact riding against the tread. This will tend to keep the contact a4rea of the wheel clean although you do need to have an easy method of getting dust out between the contact and the wheel tread on occasion. Downsides are cleaning them when they get dirty and that they don't make a sure contact with the rails. Next comes the various ways of rubbing against the flange or the backside of the wheel. These tend to be most hidden of the methods and look good on a model. Unfortunately, they are making their own contact with teh wheel and that is isolated from the contact with teh track and thus there is no cleaning action as the loco turns. Downsides are that they are another set of surfaces that need to be cleaned and they odn't promote good contact witht eh rails.
-- Why do penguins walk so far to get to their nesting grounds?
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I too use p/b contacts bearing on the track - they're self-cleaning, and once properly adjusted seem to cause no particular problems at all, though the track does need to be reasonably well-laid.
As to the visibility aspect, there are two points to consider. 1) - are they less obtrusive than the horrible finger-poking and stalling routine so typical of locos with poor pickup - answer, YES. 2) - if they're properly designed, they can fade from sight among the brake-gear on steamers, and certainly don't show between the wheels on diesel trucks. You can always finish them with gun-blue if you want them to vanish completely, but I've tended to leave them in plain metal just so I can point them out them to folks at model railway exhibitions, as otherwise they just aren't noticeable.
John M Hughes West and Wales Web at http://westwales.co.uk
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Bob May wrote:

That agrees with my experience.
Track wipers are usually the best solution, but they WILL find any bad track, with unpleasant results. I use them on my home layout with almost no problems at all. However, most of these locos cannot be run on the club layout (decent track, but not as good as it should be), or other home layouts (generally unknown track conditions), due to snagging problems.
Bottom line ... if you have really goually to FIX THE TRACK!
As for visibility, that depends on the loco in question, and the installation used. I find I can camouflage them fairly well in most cases, hiding them behind sideframes, brake shoes, injectors, or other low-hanging details. Then paint the visible surfaces dark gray. They can be seen if you look for them, but very few ever notice them if I don't point them out.
Wipers are at their best on small, light, equipment that naturally get poor contact due to too few contact points, or not enough weight on the contact points. Little 0-4-0T and 0-6-0T locos, Shays and other 2-truck geared locos, cabooses, etc.
Wipers do reduce pulling power slightly, due to increased friction and transfer of some weight from the drivers. This can be minimized by careful installation an adjustment. The greatly improved electrical contact is usually a good trade-off for it.
Dan Mitchell ===========
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I've found thtq a quarter of an ounce pressure is enough to probide excellent contact with the rails. I try to do the wipers so that the stiffness is along the track by making the spring part go along the length of the loco with a final popout to the rail, basically a L shaped piece for the spring. Soldering on a shoe with nice tipups at the ends and a decent length (1/4" long) also tends to help with the sliding action over bad spots in the track. Tender trucks tend to be difficult as 4 wheel trucks are often quite short on the older stuff and this means a cross truck wiper spring, This means that the spring action (luckily most tender trucks are unsprung) with little motion to the spring for the wiper. I've done dual spring springs (cut out the center part of the spring to decrease the force of the spring without losing the rigidity of the lateral motion of the spring) to improve the strength of the springs. Using a rod for a spring isn't a good thing to do as there is little rigidity to rotation of the shoe which will make the stubbing of the wiper on some bad joint in the track a lot more likely. BTW, I use phospher bronze for both the spring and the shoe itself. I've worn through shoes and have had to replace them on a fair number of locos and it is really nice to just solder on a new shoe rather than having to replac the whole thing.
-- Why do penguins walk so far to get to their nesting grounds?
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Tomar Industries makes some nice ones.
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snipped-for-privacy@gannon.edu wrote:

Personally, I prefer track wipers, but they come with their own whole list of problems that must be dealt with.
Wheel wipers are an intermediate solution. They're better than just relying on the rotating contact of axle to sideframe. They too have problems, most of which are related to dirt build-up and wear.
I use replaceable nickel-silver contact shoes on all my wipers, whether wheel or track wipers. These are just tiny chips of N-S soldered on the tips of the wipers. These give improved electrical contact, and can be replaced when they wear down (and they WILL!).
One handy source such N-S is the punching webs ("sprue") from Atlas rail joiners. (never throw away a good piece of n-s!)
One thing with any wiper is to keep the flex arm as LONG as possible. This allows for necessary motion without excessive pressure (and resulting friction). Using short stiff wipers is asking for trouble (example: the MDC Shay).
Dan Mitchell ===========
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I agree with all Dan's comments, especially the advice never to throw anything away!
If you really feel like trying something innovative, you could use gold for the actual contact surface - I've heard of it being done, though I've not tried it myself. It doesn't tarnish, of course, and I understand that it solders well. I haven't priced gold wire, though, but I suspect that a few inches of it wouldn't be all that expensive, and should cater for all the locos you're ever likely to need.
John M Hughes West and Wales Web at http://westwales.co.uk
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snipped-for-privacy@aol.com wrote:

The main drawback is that it's so soft it would wear excessively, compared to n-s. Of course, there are various alloys of gold that are harder, and might work 'OK'. Gold and gold-alloy wire is available from jewelry suppliers.
However, n-s is readily available, inexpensive, and works great, so why bother with gold.
Dan Mitchell ===========
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On 19 Nov 2005 09:29:46 -0800, snipped-for-privacy@gannon.edu shared this with the world:

I only add them if a loco has proven to not be able to pick up power reliably thru any other method.
That said, I tend towards back-of-the-wheel wipers. I make mine from the contact pieces that I salvage from old low-voltage electrical relays.
I picked up half a dozen old telephone switching relays for something like $2 and each has over a dozen contacts available to harvest. Enough to last me for a while.
--

Kent Ashton | http://members.shaw.ca/kjashton -personal
snipped-for-privacy@shaw.caNADA
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One of the reasons why I like track wipers rather than wheel wipers is that the latter can cause unpredictable lifting of the wheels on a sprung or equalised chassis, which doesn't occur with lightly sprung track wipers. On a rigid chassis this doesn't matter so much, though OTOH the track pickups will always be in contact with the rails, which all the wheels on a rigid chassis probably won't! If I have to bear on the back of the wheel, I prefer to do so on the very edge of the flange rather than anywhere else - they seem to run cleaner there than anywhere else.
What helps good electrical contact isn't having a large contact surface, but rather a very small one - preferably a pin-point, though this isn't usually practical. The actual pressure exerted even by a light spring on a tiny surface area can be of the order of a ton or more per square inch, which will break through most track crud without difficulty ;-) Think of the pressure exerted by the point of an LP stylus...
John M Hughes West and Wales Web at http://westwales.co.uk
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Dear folks:
I think I
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Dear folks:
Grr. I think I just double-posted again.
Looks like I have a ton of stuff to try...time to find some bronze and a pair of tin snips...and maybe some old relays.
Probably I won't go with the track shoes -- too easy to snag on trackside weeds and stuff -- but there's lots here on wipers. Thanks everybody!
Cordially yours, Gerard P. President, the electrically experimenting Sparta Railroad
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