I have a 1989 Overland brass Hiawatha F7 streamlined steam locomotive which I have painted and converted to DCC. The only problem is the manner in which the pilot wheels are attached to the frame. They are suspended by a single screw and square washer and are supposed to compress a spring when on the rails, I presume. It is a very floppy arrangement and yet when in operation, there appears to be a degree of binding at times. The result is derail and short. I have another 4-6-4 Hudson by PFM with a different suspension for the pilot wheel truck and it works just fine in the same situations. Does anyone have a thought on improving this arrangement? Thank you.
It sounds to me as if the wrong spring is in place, or it is now defective/deficient in some way (perhaps shortened or bent by a previous owner in the interest of improving performance), or it is mounted incorrectly. For example, should there be another washer above or below it to act as a bearing for the truck, below? The binding may be due to the end of the wire catching on something and acting as a deterrent to tracking.
If you press upward, using your hands, on the truck so that the flanges are approximately where they should be when taking the weight of the engine, do you feel substantial resistance in the spring in both axes?
I have the same problem with an Overland CB&Q 4-8-2. I thought perhaps enlarging the “slot” on the pilot truck would help – instead it make it worse, because I could not make it smooth enough I guess. Somehow Mantua got this right on its old metal 4-6-2 kits using a large but soft spring. I think that soft spring may be the key. It doesn’t take much downward pressure to help, evidently.
Another technique is to wrap very small gauge lead solder around the axles to give them more weight and a lower center of gravity.
I have two Spectrum N&W J class locomotives one DCC and one DC. The older DC version has exactly the same set up as you described where as the newer one has some stupid cantilevered arm set up which if a pain. On the DC model I had to weight the front truck with a small piece of lead with a little C/A on it to hold it in place. It was fine as long as you were running straight but as soon as it it hit a bump or a curve off they would come. The weight did the trick.
Weight seems to be the key. I am dealing with a troublesome pilot on a Westside PRR J-1. Seems to be a strange arrangement as well. If anyone has had this problem with this particular engine and has solved it, I’d like to hear what you did.
I tinkered with one of those CB&Q 4-8-2’s before. The problem with that model is the pilot wheels hit the cylinders on anything tighter than a 26" radius which causes the inside wheels of the pilot truck to lift off the rails, somethimes causing a derailment. The quick fix without doing any grinding on the cylinders for more clearance is to replace the 36" pilot truck wheels with some 33" wheels. Once painted it looks fine and tracks much better.
Also, be prepared to replace the gear box in that thing if you run it very often. The gear boxes that those engines came with are junk.
Thank you for your response. I had thought of smaller wheels. I did try the PFM pilot truck on the Overland F7 and it works well. Not sure if that is because the wheels on the PFM truck are in fact 33" or that the truck is able to shift laterally as well as pivot. The latter is what I am hoping as I will be able to duplicate the PFM arrangement with a little brass fabrication.
Thank you for your response. I may have found the answer. The PFM version permits lateral movement of the truck as well as pivot. When I placed that truck on the OMI loco, it no longer derailed. Now I have some brass fab to do.
That is just what I will do. I tried the PFM assembly on the OMI and it works splendidly. The lateral movement the PFM version permits seems to be the answer.
I think I have it solved. The PFM truck is able to translate laterally on curves as well as pivot. I placed it on the OMI and the derail problem disappeared. I am going to convert the existing truck to mimic the PFM. Thanks for your response.
Before I was able to read this thread, other responders provided the key advice in my opinion.
Tight springs, interference of the engine body with lateral movement of the truck, and the need to weight the pilot truck. All three of these issues were present on several of my BLI steamers before tasckling the problem with softer springs, adding weight to the pilot truck and, in some instances trimming the body or modifying the truck.
Good advice for those dealing with balky pilot trucks.