Siderods powering drivers ...

[Rashputin]

   As is now common, all these little steamers seem to have one powered driver with the siderods powering the other drivers connected to it.  I have an older brass engine, one I got used, that looks great, has only modest wheel wear as compared to most of my others, and it's worn the siderod mountings to such an extent that it's really sloppy.

   Has anyone put enough hours on Bachmann steamers, particularly Spectrum  engines, to have an idea of how much running it takes to have a similar problem on Bachmann engines?  Also, does anyone have a solution that avoids the problem altogether?


  Thanks,

  Regards

[GN.2-6-8-0]

Rare indeed is the model steamer that is powered any other way than through the siderods,though the newer Aristo G scale engines do have seperate gearboxs on each axle. No such thing in the smaller scales.
as to a solution to minimise wear on the siderods you can do one of two things,keep your running gear lightly lubricated or park'em and just admire them.

[CNE Runner]

We have a small local model railroad club in our area that has set up its layout in one of the town's elementary schools. The trains will run for 5 minutes if one presses a button. You can imagine how many times a day that button is pushed!

From what I understand the club has had to send back their Broadway Limited engines several times to have the side rods and bushings replaced. Because the layout is used by children; Broadway Limited does this service for free...'talk about a reputable company. I would imagine there are literally hundreds of hours put on each locomotive - but the exact number I don't know.

Ray

[Jim Banner]

The group I model with also has an H0 public layout that runs at the press of a button.  It is a little different than the one Ray is referring to in that it runs two trains through a set sequence at the press of a button.  And it is different in that we have a counter that counts the number of runs.  That counter is a very strong bargaining chip when we negotiate with the museum where the layout is located.

We originally ran Bachmann Plus Consolidations but now of course run Spectrum Consolidations.  We are not gentle with these locomotives.  We start them by applying full running power (i.e. enough voltage to run the trains at 30 smph) and stop them by shutting the power off.  This helps keep the locomotive wheels clean because they spin at start up and slide to a stop.  Every time the trains are run, each one goes about 60 feet or one scale mile.  Each locomotive goes about 50,000 times before failure.  That is almost 600 real miles with a wheel spinning start and a skid to a stop every 60 feet.

One of the failure modes is the side rods cutting the crank pins off the main wheels (the wheels on the geared axle.)  This usually indicates we have not been oiling the crank pins enough.  We find it is easier to turn new crank pins out of brass and mount them to the main wheels with small machine screws than it is to send the locomotives over the border for repair.  So far, we have never cut off a replacement crank pin.

If you really want a solution that will avoid the problem altogether, consider small brass or Oilite bushing set in the holes of the side rods and hardened steel, ground and polished crank pins in the wheels.  Oil the bushing every 100 scale miles or so and disassemble and clean them every 10,000 scale miles.  They won't be cheap but they will last a very long time.

Jim

[FECfan]

Yeah regular Maintence is good, I have an IHC Pacific that has a lot of scale miles on it, and about a year ago I had all of the side-rods replaceds because I never lubricated anything, now I know better, and got to my mikado before it had the same thing happen!

[Rashputin]

Jim Banner   


  "One of the failure modes is the side rods cutting the crank pins off the main wheels (the ]wheels on the geared axle.)  This usually indicates we have not been oiling the crank pins enough."



    I put oil on the pins about every 15 hours of operation using a tooth pick to pick up just a small drop and let it run off onto the pin.  Is that sufficient as to quantity and frequency?  I no longer have the dexterity to make modifications as you suggest, but if there's a write up somewhere with a list of components I need to make bushings or where to buy them, my son may be able to.  I like the Idea of bushing in the rods, it seems like a more failsafe approach than relying on lubrication alone.

  On the other hand, you run yours so much I don't have any idea how long it would take me to have that much wear.  I also don't know how long it would take me to replace engines I've spent years getting together in order to have a layout, so it's pretty much a better safe than sorry situation the way I see it.  I remember times when there weren't the wide variety of quality engines available that there are now, and those times generally followed a major downturn by a year or so and then took a long time to recover from.

  Regards

[Jim Banner]

Installing Oilite bushings is a lot of work.  Each bushing must be turned to a size that can fit into an enlarged connecting rod hole.  Oilite is difficult to solder or glue because of the oil contend, but you can turn them with a shoulder, press fit them into the connecting rods, and stake them very, very gentle so that they don't break up in little pieces.  This is a good choice if the crank pins are in perfect condition because with a thin enough flange, and by eliminating some washers or spacers, you may not have to replace the crank pins.  The biggest advantage of Oilite bushings is that you rarely have to lubricate them.

Brass bushing can be a lot easier to install.  Basically, you drill some holes that will fit your new crank pins in a piece of sheet brass.  Then you cut out circles or squares of brass centered on the holes.  Lastly, you solder one of the washers you have just made to each side of the connecting rods.  Use the pin sized drill to hold the washers centered while you solder.  If you are lucky, you will find some small brass washers with holes smaller than your crank pins.  Then all you have to do is drill them out to size.  Something around .030" thick is fine.  This will about triple the thickness of the original bearing surfaces on the connecting rods, depending on how thick the original rods are.

The increased thickness of the rod ends will likely required slightly longer crank pins.  You might get away with the old ones, particularly if there are washers that you can discard, but if the pins are worn, this is not a great idea.  Initially, the wider bearing surface of the connecting rods may span the grooves worn into the pins and the locomotive will run well, for a while.  But that happy state of affairs usually will not last, and then you are looking at replacing the added on bushing, again, and still having to replace the crank pins.

Crank pins are generally of two types.  One type is a machine screw with a short thread at the end.  The shank of the screw forms the pin.  The thread attaches it to the wheel.  These are often (always?) made of steel and generally outlast brass or nickel-silver connecting rods.  This type is generally seen on brass locomotives.  The other type is either cast integral with the wheel or is press fit into the wheel after machining.  This type is usually either brass or a die casting alloy.  Being as soft as or softer than the connecting rods, these pins often wear out before the rods do.  These pins are usually found on plastic bodied locomotives.

Replacing a pin is easy if it is a screw in type and the manufacturer is still in business.  Replacing a cast in place or pressed in pin is a little harder.  I have never had much luck with pressing out old pins and pressing in new ones, so I generally treat cast in place or pressed in pins the same way.  Basically, that involves drilling a hole through the center of the pin, cutting off the old pin, and attaching a new pin with a small machine screw.  It sounds easy, but there are a few tricks involved.

To drill a small hole the length of a crank pin, keeping it exactly centered and on axis, is quite difficult.  So I cheat a little.  First I make a centering guide by drilling lengthwise through a short piece of brass rod, using the tap drill for the machine screw I will be using later on.  Then I drill part way through the rod with a drill the size of the crank pin.  The result is a sort of cap that fits on the crank pin and gives me a guide hole exactly centered on the pin.  I usually make this guide cap on the lathe, but with careful working, a drill press is all you really need.  The crank pin sized drill will automatically follow the tap drill sized hole and be concentric with it.  Then I cheat again.  Drilling all the way through the crank pin is a boring job (pun intended) so I usually cut off most of the pin, leaving just enough to center my centering guide.  Sometimes I will clamp the axle in a drill press vise while drilling (NOT ON THE GEAR!!)  Other times, I will do it on the lathe using a four jaw chuck and dial indicator to center the crank pin.

When tapping the holes in the wheels, do so before cutting off the last bits of the crank pins.  Small taps, particularly the flat sided triangular ones, can be difficult to start and often pull out the first few threads.  In some wheels, you only get a few threads once the crank pin is cut off.  I prefer to throw away any damaged threads with the nub of the pin.

I usually make new crank pins on the lathe, turning them to the same diameter as the old ones and tapping them lengthwise for the machine screw.  If this is not an option, you may be able to find a standard tubing size that is compatible with your chosen machine screws.  This may well require a different sized hole in the connecting rods.

When you run your machine screws through your threaded crank pins, start them at the end of the pin where the tap came out last.  The other end of the pin, the one you drilled and tapped from, is more likely to be perfectly centered and therefore a perfect match for the tapped hole in the wheel.  Remember to include a washer between the head of the machine screw and the threaded crank pin.  This will keep the rods from sliding off the pin.  What you end up with is a crank pin much like what is used on brass locomotives, complete with a smooth shank of the right diameter and a short thread to screw into the wheel.

Long winded explanation, I know, but I hope it helps.

Jim 

_{edit: spelling, punctuation}

[Rashputin]

   Thanks for the detailed information.  I wouldn't call it "long winded", I'd say it thoroughly covered the subject.

   Regards