Thanks to Ron Dodd’s videos I am taking more interest in the mechanical side of my engines. I had a poor running Bo-Bo which on investigation seemed to need new brushes as they were very worn. New brushes were fitted nothing else was touched.
On test, upside down with crocodile clips attached to the pick up and earth it ran smoothly. I let it run for about 10 minutes to bed in the new brushes.
Put it on a straight bit of track and off it went but stopped dead at the first curve, push it and it starts but stops almost immediately. Pushing it around the half circle it came to the straight and off it went but after about 4 lengths it stopped again. Reversing the direction of the engine made no difference. Pick ups were cleaned including the inner sliding mech with a cotton bud and neither seem to be sticking at all.
All wiring checked and the earth was resoldered as it looked flimsy. Engine still runs without any problems on test bed.
There is no sparking that I can see when the engine stops.
As explained when on test upside down the engine runs perfectly but won’t run on the track around curves or even on some straight bits.
I set up a small test track with two curves and a straight. Cleaned the track and checked it with an N2 – track OK. Then the Bo-Bo stutters then stops. I left the front bogie on the track with its pick up and lifted the rear bogie to the side of the track and it ran well but when I moved the front bogie a little it stopped.
My theory is that the insulating washer on the front pick up which is very loose and when the bogie moves it produces a dead short as the pick up washer touches the chassis. So I need to remove the pickup and replace the washer although I will have to make one up from some plastic. The questions are – is this likely and how do I remove the plunger pick up to replace the washer? Is it in Ron’s videos?
This theory explains the upside down running as the insulating washer and the connector would not be able to touch the chassis.
More testing has indicated that my pet theory might well be wrong.
Engine on track, controller on – no movement. With screw driver put pressure on front bogie pick up piston – motor starts running. Take pressure off motor stops.
Seems that the pickup is not making contact with the third rail. Might still have to dismantle the pick up but will try cleaning etc.
White spirit and a cotton bud cleaned the pickups and they now drop down the full extent.
I then remembered that I had fitted a Neo magnet as well as new brushes. If things can be put in 2 ways I usually choose the wrong way first. So the Neo was taken out and turned round – it looked square to me but I turned it round anyway.
Net result is that the engine can now complete a circuit of the track without stopping. What was the Neo doing to make it keep stopping? It was one that was specially supplied for a Bo-Bo.
Final conclusion after all this work, including new tyres is that the engine runs no better than before and still hesitates occasionally just as before.
Put it down to experience