Double heading on DC layouts

[markwilson]

I have a DC layout in N gauge with various stock from Graham Farish and Dapol.  On occasion, I think it would be good to run two Farish class 108 DMUs coupled together (or my Dapol 121 with a Farish 108; or a couple of diesel locos), but they run at different speeds. I was wondering, please could some of the experts here tell me if it is "safe" to have two locos (or two multiple units) coupled and running together on the same track, or am I likely to cause damage to the motors (or something else)?

[LongRail]

Mark

 

I run DC in 00 guage and often double head using engines with different characteristics and they don't seem to suffer any ill effects.

Transformer is also happy.

[Poor Old Bruce]

At the York exhibition a few years ago there was one clown operating a 00 layout using a Class 20 and Class 08 coupled together to do some shunting. He was totally oblivious to the fact that the two locos had different characteristics and that the 20 was overpowering the 08 which, although the wheels were turning, was being dragged backwards and forwards by the 20. That said, if your two units are 'reasonably' compatible, you shouldn't have any problem.

[markwilson]

Thanks for the replies Bruce and LongRail.  Thankfully even my 10yo son had the sense to realise our two 47s are so different they won't work well as a pair but the DMUs seem OK.  Sounds like I'll be OK the if I use a bit of common sense :-)

[Londontram]

I would place both locos on the track at the same time but not connected and run them to see how balanced they were before running them double headed, surprisingly some same class locos were not always compatible. I did have a couple of old Triang 3F and took the motor out of one but cross wired them for maximum pickups and they ran permanently as a pair of bankers cross wired this didn't overload things when banking a train as you still had a maximum of only two motors - the train loco and one of the bankers. Note IMO I found if your using three link couplings it was best to place the faster loco (one is always slightly faster than the other, even on the most balanced pair) in front, there's less chance of buffer lock on points etc even on the cross wired 3F pair the motor fitted one was the leading one.

               Steve

[DCB]

I know the original query was N gauge but in OO apart from some freaks like the Bacchmann Gronk and Hornby 42X/72XX most locos will work adequately double headed on variable voltage controllers, such as the Hammant and Morgan Safety Minor variable transformer or OnTrack and Morley electronic units, even locos which are hopeless double headed on variable resistors run acceptably on variable voltage.    The variable voltage units will show around 1 volt on minimum power and no load whereas variable resistors will typically deliver 16 volts.

I guess the use of an n gauge Morley or on Track which have around a 1/2 amp max current and more sensitive circuit breaaker against 1 amp plus for the OO version would ease the original problem

[John_Miles]

Isn't there problem if you use a feedback controller? My understanding is that the controller gets "confused" at receiving feedback from two motors and this results in both engines running unsatisfactorily. Some controllers (e.g. Kent Panel) allow you to switch the feedback off.