Rolling roads and electro magnets

[Jimbobwhale]

I have a couple of things bothering me and I would appreciate your thoughts on them please guys.    Firstly I have just invested in a dcc concepts rolling road in order to run in my new A4 loco.  It's a dapol so has pick ups on 14 wheels (all eight wheels of tender have pick ups on them) as well as six on loco itself.  I have found that there is not enough space to put a rolling road under all the tender wheels so I can only have two sets of the four working   Is that ok for running it in or do all pick up wheels need to be working to properly run it in?  The second thing that I'm not sure about is a peco electro magnet that emits a humming sound when I press the switch to work it.  It's the only one that makes this sound as I have fitted 12 alltogether (they all work fine by the way). I would appreciate your thoughts on both these issues please my friends

[chrism]

The second thing that I'm not sure about is a peco electro magnet that emits a humming sound when I press the switch to work it.  It's the only one that makes this sound as I have fitted 12 alltogether (they all work fine by the way). I would appreciate your thoughts on both these issues please my friends

How is the electromagnet energised? DC or AC supply?
If the latter, could the electromagnet be slightly loose, allowing it to vibrate a tad?

[ntpntpntp]

I have just invested in a dcc concepts rolling road in order to run in my new A4 loco. ...  I have found that there is not enough space to put a rolling road under all the tender wheels so I can only have two sets of the four working   Is that ok for running it in or do all pick up wheels need to be working to properly run it in? 

Running in is about freeing up the mechanism's moving parts, spreading any lubrication, looking out for loose or damaged parts etc.  As long as you can get power to the model that's all you need for a rolling road test.  Also keep in mind that a rolling road test doesn't fully exercise the model in the same way that running round curves does.  That's why I consider a figure 8 test track to be the best choice.  With a figure 8 track diesel and electric loco bogies get swivelled both ways and the gear towers run at extremes of twists etc. Steam locos get to run with their front pilot wheels on the curve (might catch with the valve gear if there's a problem?)

Of course you need all the fitted pickups to be working as they should, but that's more about electrical testing with a meter if you think there may be a problem. Pickup issues may not show up on a typical running-in test unless your test track includes dead frog points etc. A rolling road is unlikely to show them up unless you happen to chose the duff pickup wheelset as one of the supported axles.




I agree with @chrism about the buzzing electromagnet.  AC will make it hum more than DC, and if there is anything a little loose then you may get a buzz.
It can happen with all sorts of equipment which has an AC transformer inside, sometimes the construction of a particular unit has a little slack in it somewhere and any natural hum becomes a buzz.   My multi-change CD player in my HiFi has always had much more hum than any other unit in the rack, I keep meaning to have it apart and sort it out with some packing or muffling maybe, but I've never got round to it in 20+ years