Good news, I finally got my PCM Big Boy back from PCM for repairs. It arrived new with a bad power cord and worm gears where not right. As much as I bragged about the PCM Y6-b, a healthy PCM Big Boy makes it seem like a wimp. (Y6-b is still a great engine)
Big Boy is a DCC ready engine and I am getting ready to buy sound. One thing I have to wonder about is sometimes I hear a clicking sound, it not a bad center gear. I know what a bad center gear sounds like. I have replaced more than my fair share of them.
I have oiled all the side rods, but I stall hear a lite clicking mainly around turns but not all the time. I have been running heavy loads, 50 foot cars and 50 cars all NMHA weight if not a little over weight.
Getting ready to run it with out a drag to see if it makes the same clicking.
All I can suggest is that you invert the engine in a soft cradle, apply power to one of the tender axles, get the rods moving, and then gently press each of the driving axles to one side, then the other, and listen for the clicking. Once you hear the clicking, at least you’ll know which axle is causing it when it slides sideways as the engine encounters a curve. You’ll have to gently tease one or more rods apart so that they don’t connect at some point.
Check and see if the main rods have been bowed inward. The crankpin screws on the second drivers of the front engine are the most probable culprit for the clicks you heard, with the same axle on the rear engine as first runner up. Possible solutions include gently bending the main rods outward, putting shim washers on the main driver crankpins to space the main rods away from the siderods and (as a last resort) adding shim washers to the offending axle(s) to reduce side play.
My Proto 2000 2-8-8-2 made a clicking sound. The running gear was fine, but one of the eccentric cranks was hitting one of the added-on pipe details. Maybe you have a similar problem.
Thanks for all the answers. I pretty much knew it was going to have to go on its back and be ran. It is tuff to handel, I may have bent something my self.
All of the suggestions are good ones. I have also seen locos where the back of the rod(s) occasionally strike the counterweights, resulting in the clicking noise. If the rods aren’t bent inward, the solution is a spacer washer to move the rods slightly outward, away from the wheels. Another one that I encountered recently is where the piston rod is too long, striking the inside of the front cylinder head. While this is rare, the real cause was that the cylinder casting had rotated slightly on its mounting screw, moving the cylinder head slightly to the rear on one side. I straightened the cylinders, but also trimmed a little off the front ends of both piston rods. Every time you work on a steamer, there’s a good opportunity to learn something new. [swg]
In addition to the siderods, check clearances on the valve gear parts. I’ve had a few Bachmanns that clicked due to a small burr on one of the crosshead guides.
Also check the drivers for any front-to-back, or vertical play that becomes more noticeable under load. I had an old Rivarossi with a driver that would lift, then snap back down onto the railhead, but it resolved itself after a break-in period.
Side-rod clicking (for me) is usually caused by the front wheel bolt binding with the crosshead very slightly, so that’s another thing to look for. I fix it by putting a spacer between the frame and wheel on the opposite side, so the axle can’t slip over far enough for the bind to happen.
Ken the crosshead is the (sometimes) square block that slides forwards and backwards as the piston does. The main rod is pinned to it on one end and to the main driving wheel on the other. It runs on a guide sometimes as a single rail and other times as two rails. Those rails are the crosshead guide(s).
scroll down to just under “Connecting Rods” and you will see a good image of the crosshead and the guides it runs on.
Personally, I feel the more likely impact would be between the crosshead itself and the driver counterbalances than with the thinner guides, but I guess it depends on the engine and the type of crosshead.
