Wiring two motors together

[1466]

I’m building a GWR twin car railcar . It is inspired by an article by the late Monty Wells from 1985 in MRJ number 6.

I want to wire the motors in each railcar together  but the  Hornby wiring is fragile and complex . I guess I’ll have to join positive to negative, as one is effectively running in reverse ? 
Any suggestions on how to join the wiring from one railcar to the other will be welcome .

Thanks 

Ken 

[Right Away]

Assuming both motors collect power from the track why the need to wire the two together?

Using DC only, the polarity of the feeds of one motor will need reversing.

If DCC with two decoders (extravagant!) just set up a Multiple Unit consist.

 

Edited February 10, 2021 by Right Away

[melmerby]

Do you need two motors? A bit extravagant for two vehicles.

Why not replace one with a plain bogie?

[1466]

Thanks for your comments.

Although the motors should be identical, they tend to fight each other slightly . I wanted to wire them together to counter act that tendency , to lengthen the contact area for pick ups and to equalise the current. My track work isn’t too bad but occasionally there is a dead spot near a point . Thanks Right Away for  confirming that I need to reverse the polarity on one motor . This is dc .

Melmerby , originally I planned to use a white metal kit which weighed a ton . I’d bought the Hornby chassis so decided to stick with them. I don’t have a need for what would be the now redundant power bogie . So ... inertia on my part , i guess .

I appreciate your interest chaps . Thanks again .

Ken 

[F-UnitMad]

My experience is with twin-motor O Scale diesels. If you really need two motors I'd be inclined to put both of them in the one car if possible, & have the other as an unpowered 'dummy'.

There are two ways to wire twin motors - in 'parallel' or 'series'. Parallel means wiring both poles of each motor to the pickups (in DC). They will both get full power. In simple terms this means wiring both + poles to the pickup for one rail, and both - to the other. If the motors are facing in opposite directions, as you seem to infer, then wire the 1st motor's + and the 2nd's - pole to one rail pickup, and the 1st's - and 2nd's + to the other rail pickup.

 

For series wiring this shares the power between the motors. Smooths out the running, aids slow speed creep but does reduce top speed. This might be an advantage on a smaller layout. A downside to series wiring is that if one motor sticks or stalls the other will take all the power & spin up quite merrily, with a lot of wheelslip!!

But to wire in this way, wire the 1st motor + to the one rail pickup, then wire it's - pole to the + of the second motor, and the 2nd motor's + to the other rail pickup. Again if the motors are facing opposite ways, change the connections to rail = motor 1 +, motor 1 - to motor 2 + , motor 2 - to other rail.

 

To keep track of the wiring it's best to try & colour code it, and it's also easier to do all in one model than having to cross the gap with jumper wires, hence my suggestion to fit both motors in one unit!!

[1466]

Thanks  F-UnitMad that is clear and very helpful . Thanks .

Ken

[1466]

20 minutes ago, 313201 said:

Hi Everyone, 

 

I must admit these new motor bogies for diesel and electric outline locos/units are more complex to workout when it comes to the wiring.

 

I bought a railroad range regional railways class 37 ( 37414 ) and had hoped to double motor the loco by purchasing a  2nd powered chassis for it but when I saw how the wiring was set up just for 1 motor it made me question how easy would it be to actually do it.

 

I believe the  GWR twin units were at 1 point added to with a middle coach and the controls for both driving coaches wired together so that both the engines on the units worked together.

 

Also on the new Hornby motor bogies, they have 2 wheels with traction tyres which are not their best because aswell as the regional railways class 37 I also bought a railroad EWS liveried class 66.

 

Within a month of a purchasing the 66, the tyres had gone completely awol and more recently the tyres on the 37 have done the same.  The best advice here, add weight to the driving coaches  so that the tyres wheels could be replaced if possible but adding weight will aid traction.

 

Hope this helps

Hi 313201 .

I, too, marvelled at the complexity and delicacy of the wiring .The photos I attached show a cats cradle of wires .

You are correct that the twin car units did have at one time a coach inserted between them . It was possible to drive all 3 from each cab  using air pressure ( I think). 

With regard to traction tyres ; I had by passed this problem because  I had converted the units to EM gauge using the excellent Ultrascale products .

Thanks for your interest .

Ken I

 

[melmerby]

11 minutes ago, 1466 said:

 

With regard to traction tyres ; I had by passed this problem because  I had converted the units to EM gauge using the excellent Ultrascale products .

Thanks for your interest .

Ken I

 

You are lucky

IIRC The original Lima version had traction tyres on one wheelset (2 tyres) but only picked up on one side, so one wheel only was typically in contact with the rail , on the other bogie the other side had contacts. So likely only 3 wheels were picking up current!

Mine has a black beetle bogie and contacts on all 8 wheels of the railcar so is streets ahead of the Lima original.

Edited February 10, 2021 by melmerby

[Harlequin]

The wiring may be complex underneath but it is brought to a very simple interface that you can exploit - the 8-pin DCC sockets.

1 8

2 7

3 6

4 5

 

Pin 1 is usually marked.

Pins 1 & 5 feed the motor.

Pins 4 & 8 pickup power from the track.

 

If you remove the blanking plates you could wire two decoder plugs together in such a way that the motors are connected together however you like and plug one end into one loco and the other end into the other.

 

No need to touch the loco’s wiring at all!

[Dagworth]

18 minutes ago, Harlequin said:

The wiring may be complex underneath but it is brought to a very simple interface that you can exploit - the 8-pin DCC sockets.

1 8

2 7

3 6

4 5

 

Pin 1 is usually marked.

Pins 1 & 5 feed the motor.

Pins 4 & 8 pickup power from the track.

 

If you remove the blanking plates you could wire two decoder plugs together in such a way that the motors are connected together however you like and plug one end into one loco and the other end into the other.

 

No need to touch the loco’s wiring at all!

All you need to do if they are staying DC is to  solder a pair of wires between the blanking plugs themselves. 
 

The wires would need to go from pins 1&8 on one plug to pins 4&5 in the other and the same the other way. You can quite safely solder across both pin 1&8 etc. as they are linked electrically within the plug. This would give you a stronger connection than trying to solder to a single pin. 
 

Andi

[1466]

Brilliant . Thanks Harlequin and Dagworth .

Ken

[Harlequin]

@F-UnitMad's suggested of connecting the motors in series requires a different arrangement and you would have to modify or make new blanking plugs to disconnect the motor from the pickups in one (or both) of the locos.

 

DCC wiring has a colour convention so probably best to stick to that:

1: Orange (Motor right)

4: Black (Rail left)

5: Grey (Motor left)

8: Red (Rail right)

 

Edited February 11, 2021 by Harlequin

[1466]

I want to thank everyone for their erudite contributions .

Ken