Slow speed stalling switcher


Rico

Rico

BN Modeller
Just wondering if anyone with a BLI (sound equipped) switcher has experienced stalling over switches at low speeds?
I've metered the wheels and pickups and everything came out okee dokee when off the rails, yet the wee beastie still stalls for a moment when it hits a frog.
(doesn't happen on Peco's, but on Atlas, Shinnohara's and ME's)
It's a little frustrating when the sound stops then the engine fires up again before carrying on.
I've thought about powering the frogs, but my Bachman 70 tonner and small Athearn units all sail thru like champs at low speeds.
Next step will be to disassemble the unit and trace the entire circuit...
Here's a couple pics of #121 switching out the Fuerst Matthes Paper Mill:
 
Unfortunely Decoder equipped locos are by their nature much more sensitive to momentary loss of electrical contact such as unpowered frogs than their DC brethern. :(
 
I think your idea about a problem with the BLI unit is probably correct. If the Bachmann 70 tonner goes through without stalling, the switches are fine. My 70 tonner is my test unit for all switches. If there's a problem, it will do the momentary stall. In addition to tracing the circuit wires, I'd think about testing how level the trucks sit on the tracks. One wheel slightly lifted by a an out of round axle or binding sideframe can cause the stalling problem you describe. A flashlight on the other side of the locomotive while it's going through a switch should show you any small gap in the wheel set.
 
Another test to add to Jim's out-of-level test is checking that all wheels are in gauge side-to-side. I have a switcher that has one wheelset slightly narrow causing it to ride up on the frog, in turn causing a stall at slow speeds. Another wheelset is slightly wide which causes other issues. This thing hates Atlas turnouts!

But it is the engine I use for testing when building turnouts as the wheels are all basically "in spec" (albeit out of adjustment) so if it makes it through, the turnout is good.

Mark
 
The problem with BLI's NW-2's and SW7's is exactly that, the wheel's are sometimes out of gauge and the flanges are REALLY shallow.
 
Ahh, thanx guys I'll look into that wheel / axle thing.
Rotten thing to happen to a locy that spends its life going over switches!
 
I have 3 BLI's and have some problems with atlas turn-outs. Your problem might be shorting out and not loss of power. The problem I've found is the cross rail at the frog. Sometimes the wheel will contact both shorting out and pausing the engine. I've had luck using a screw driver and file to widen the gap.
 
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