I have a Large Scale 4-^-0 Bumble Bee locomotive and Im running on Piko track. The curves are R-3 as well as the switchs. The front truck derails on the curves as well as the switches. Any idea why, And how I can prevent this from happening? I bgot this 2nd hand and someone glued some washes to weigh it down.
Since someone has already weighted the leading truck,the problem is more likely in the track.
A common misconception is that train set track is made perfectly and fits together perfectly. In reality, this is rarely the case. Consistent scientific analysis can locate and fix the problems.
Run the engine very slowly to identify the places where it continuously jumps the track. It will certainly be the same places every time and will certainly be either at a joint or a switch point.
At the subject joint, run your fingernail along the inside of the railhead at the joint, both directions, and see if you feel a little difference in a rail alignment. It could be the joint being slightly kinked, the rail joiner being slightly loose, allowing the rails to not align correctly, or a slight difference in railhead height. Assure correct alignment of the track if you see these issues.
At a switch point, the issues could be similar, but a small piece of debris could also have become lodged between the switch point and the main rail which is called the stock rail, creating even a very tiny gap, which can pick at a wheel flange.
The end of the switch point itself can sometimes be too sharp at the top, with a severe 90° corner on the top that can also pick at a wheel. Sometimes it needs very light treatment with a file. I won't try to describe this here, it will take too long. There are a number of videos on YouTube about how to service troublesome switches to avoid derailments.
These issues are very common on every Model Railroad, and development of modeling skills to treat issues like this is a part of Model Railroading. One can also keep in mind that these very same issues can plague the real railroad, but they have experienced trackwork and maintenance crews that are busy all the time maintaining track which, even in the real world, needs constant attention to avoid problems..
Inspect your front truck:
(1) Make sure the truck frame is not cracked or broken anywhere.
(2) Make sure it slides easily from side to side and is not binding on the red/black pickup wires.
(3) Inspect the plastic "axles" that hold each pair of wheels together. With age and under pressure of press fit they will crack and the wheels will loosen, spread apart and go out of proper gauge. New axles are here:
https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_148&products_id=11238