Motor removal to create a dummy loco

[APT Fan]

Good morning,

I've ended up with a fleet 56s of various vintages and most have been converted to DCC. I'm interested in double heading and looked into DCC consisting which has proven problematic. I have a spare 56 Mainline chassis and was thinking of removing / disabling the motor so that it can be used to act as a towed 'double head'. I'll probably put a rectifier in there too to power the lighting of a DCC converted body.

 

Does anybody have any experience with this?

 

Thank you in advance

[Pete the Elaner]

I have made a couple of dummys from Lima 31s.

I decided to remove some of the gears. With the motor physically disconnected, the loco rolls but creates a little more drag than a coach.

Removing a wire will electrically disable it.

 

I sound fitted one of mine & wanted the ability to read back CVs, so this left me a choice of fitting a big resistor or leaving the motor connected. I chose the latter. It therefore spins as it moves but I cannot hear it above the engine sound.

[APT Fan]

7 minutes ago, Pete the Elaner said:

I have made a couple of dummys from Lima 31s.

I decided to remove some of the gears. With the motor physically disconnected, the loco rolls but creates a little more drag than a coach.

Removing a wire will electrically disable it.

 

I sound fitted one of mine & wanted the ability to read back CVs, so this left me a choice of fitting a big resistor or leaving the motor connected. I chose the latter. It therefore spins as it moves but I cannot hear it above the engine sound.

 

 

Would it be possible to avoid fitting the resistor by disabling back emf?

 

I'm not sure I'm going to fit a decoder, I might just with a rectifier with a switch mounted in the chassis for the lighting à la Bachmann.

Edited January 21, 2021 by APT Fan

[Pete the Elaner]

A resistor would just be to enable readback of CVs from the decoder, not for any operational purposes.

If you are happy to set up the decoder once & forget about it, a load across the motor terminals would be unnecessary.

[DCB]

It is usually best to use two unpowered bogies rather than strip gears from the powered one not least because of the traction tyres and or grooves. What you don't want is any wheel-back pick ups as this can easily equal the drag of three coaches, I have improved steam loco traction from 4 to 7 coaches up a 1 in 36 by stripping out tender pick ups.   Then again I habitually double head and bank trains using DC.  Most combinations work but it does need a way to vary the voltage, in the way Morleys and On Track do rather than using a resistance or feed back controller.   Sticking to one make and type of power bogie has to be the answer to most of the issues.   Maybe MU connection cables between locos would also help synchronise the two locos.

[Dave-5-5-7]

I've done similar with my Lima 47. I fancied having 47380 and 47319 double heading as they're both Immingham machines. 319 is a lovely renumbered Heljan and 380 is a lima model which isn't bad looking. 

[APT Fan]

9 hours ago, Pete the Elaner said:

A resistor would just be to enable readback of CVs from the decoder, not for any operational purposes.

If you are happy to set up the decoder once & forget about it, a load across the motor terminals would be unnecessary.

 

 

The to protect the output stage of the decoder? I suppose a decoder without motor control could be fitted? Actually I might have a faulty one with a dodgy output stage, I might see if if can still control lights.

[APT Fan]

4 hours ago, DavidCBroad said:

It is usually best to use two unpowered bogies rather than strip gears from the powered one not least because of the traction tyres and or grooves. What you don't want is any wheel-back pick ups as this can easily equal the drag of three coaches, I have improved steam loco traction from 4 to 7 coaches up a 1 in 36 by stripping out tender pick ups.   Then again I habitually double head and bank trains using DC.  Most combinations work but it does need a way to vary the voltage, in the way Morleys and On Track do rather than using a resistance or feed back controller.   Sticking to one make and type of power bogie has to be the answer to most of the issues.   Maybe MU connection cables between locos would also help synchronise the two locos.

 I'm not sure how to fit an unpowered bogie as they have different mountings.

[newbryford]

I have a few "unpowered" by the method of removing part of the gear train as a dead drag.

 

Bachmann 66, 57, 37 and 20, Hornby West Country, 31 & 153, Dapol 68, Heljan 33 for example.

(The spare drive train parts are often stored inside the loco body so I don't lose them!)

 

In the case of the 57, 31 and 20, a speaker was fitted into them and a 2-pin plug used between the powered and unpowered locos - connected in parallel with the main loco speaker.

 

They also have standard motor decoders fitted to power/control lights. So they retain pickups.

 

I program them in parallel with a decoder fitted to a motor tester as a "dummy load". When I'm done, the decoder in the tester is simply reset to default.

Edited January 21, 2021 by newbryford

[Dagworth]

3 minutes ago, APT Fan said:

 

 

The to protect the output stage of the decoder? I suppose a decoder without motor control could be fitted? Actually I might have a faulty one with a dodgy output stage, I might see if if can still control lights.

Having no motor present will not damage the decoder in any way. 
 

Andi

[APT Fan]

2 minutes ago, Dagworth said:

Having no motor present will not damage the decoder in any way. 
 

Andi

 

I didn't think so either, the decoders use FET output stages don't they? The resistor comment confused me and I assumed it was for protection. Without it, its just open circuit, but I would have thought short circuits is the thing to guard against.

[Dagworth]

The resistor just acts as a dummy load that draws a little bit of current for the programming acknowledgment pulse. Many command stations cannot program decoders without the pulse being read to prove the loco is present. 
 

(the simple answer as Mick Newbryford says, is to program a second loco or other decoder set-up at the same time which provides the ack pulse, the second loco can then be reprogrammed on its own afterwards)

Personally I don’t bother with lights on any dummy locos, they sit behind the active loco so don’t need them. 
 

Andi

[newbryford]

22 minutes ago, Dagworth said:

The resistor just acts as a dummy load that draws a little bit of current for the programming acknowledgment pulse. Many command stations cannot program decoders without the pulse being read to prove the loco is present. 
 

(the simple answer as Mick Newbryford says, is to program a second loco or other decoder set-up at the same time which provides the ack pulse, the second loco can then be reprogrammed on its own afterwards)

Personally I don’t bother with lights on any dummy locos, they sit behind the active loco so don’t need them. 
 

Andi

 

I have the lights enabled on the non-powered locos as they can then be used as a light engine double header or in top n tail mode on a short set such as a RHTT set, or tail end charlie on a ralitour set. In some cases, using the decoder to power a flashing tail light.

Edited January 21, 2021 by newbryford

[Dagworth]

12 minutes ago, newbryford said:

 

I have the lights enabled on the non-powered locos as they can then be used as a light engine double header or in top n tail mode on a short set such as a RHTT set, or tail end charlie on a ralitour set. In some cases, using the decoder to power a flashing tail light.

Makes sense, but my dummy locos are 86s so very rare to need lights on them. I have noticed that we don’t run anything like enough light engine movements though, looking at videos from the 80s there were loads! 
 

Andi