Making a double locomotive of two Märklin 3148, NSB Di5, with drum commutator motor
Updated 23.06.2012
NSB Di5, Märklin 3148, connected with a current conducting coupling bar
Double traction
I do not know if the NSB Di5 ever went as double heading. But I think this
looks like an interesting combination, so I just had to make it.
Some tests were made in Germany with a double V60, but the tests were stopped when the
V90 arrived.
Märklin 3148, NSB Di5 model
The locomotive is based on the old Märklin V60, later 260, like the 3064. That means small flat
collector motor (SFCM) and normal couplings. The 3148 did not have Telex.
The conversion
I started the conversion before the conversion set 60903 was available, so the
only option was 60901, which does not fit in the 3148 chassis.
I wanted as short distance between the locomotives as possible, and with the
drum collector motor (dcm) as the only option, the choice was quite simple.
I needed two newer locomotives, with possibilities for guided close coupler pockets and dcm.
I got the 34641 (red wheels) for my birthday in 2000 and bought the
37649 (black wheels) some days later.
Locomotive inside
Connection between the locomotives
The two locomotives are connected only by means of the current
conducting coupling. The two c91 decoders, fed from one pick-up shoe, are set
to the same address and adjusted so the two locomotives runs as close to synchronous
as possible. Only the front light bulbs are installed.
I was thinking of running both locomotives with one decoder (as I do in my Märklin 3346,
double DB 236), but that requires five wires between the two locomotives.
That is difficult with the guided close coupler pockets.
The front locomotive:
This locomotive, Märklin 37649, already had the correct motor and decoder. The rear Telex was removed and a close coupler pocket was installed in it's place. The front coupler hook was replaced with the yellow one removed from 34641. The pick-up shoe is under this locomotive.
3148B left hand side:
3148B right hand side:
Current conducting coupler:
After removing the Telex coupler, a coupler guide, Märklin part no. 392730, and
a coupler pocket, 392740, was installed.
One "arm" was cut off one of the Y-shaped contact tongues from the current
conducting coupler set 7319. The "arm" was installed inside the rear
coupler pocket of the front locomotive from the inside. The end of the tongue
was bent up in a small "L" on the outside of the pocket, to prevent it
from sliding in when the "tow bar" is inserted in the pocket.
A red wire is soldered to the inner part of the tongue.
Light guide, rear upper light:
The rear upper light guide was removed from the 37649 body. It has a
different shape than the one in the 3148 body, to avoid conflict with the
different motor magnet. The light guide from 3148 was installed in
the 37649 body.
This is seen from below.
The Rear locomotive:
I removed everything from the 34641, except for the front Telex coupler and bulb
holders. A close coupler pocket was installed in end 2. This was a
new locomotive, so all the moving parts, like gears, wheels, axels and rods
worked perfectly.
A 60901 conversion set was installed, the decoder in a 258820 holder. The screw
from the removed pick-up shoe was used for the decoder holder.
The red wheels will be painted in a very dark NSB gray later on.
3148C left hand side:
3148C right hand side:
Current conducting coupler:
After removing the Telex coupler, a coupler guide, Märklin part no. 392730,
and a coupler pocket, 392740, was installed.
Here the red wire to the decoder was soldered directly to the end of the current conducting
"tow bar", from the Märklin set 7319.
This was done before the coupling rod was pushed into the pocket.
The red wire goes via
the rear bulb socket, which now serves as a distributing point.
Reversed wire connections:
The green and blue wires to the motor was swapped, compared to the front locomotive.
So was the light in the front end. This must be connected to the yellow
wire, which is for the rear lamp.
Light guide:
The rear upper light guide was swapped with the one in the 34641 body. It
has a different shape than the one in the 3148 body, to avoid conflict with the
different motor magnet. The light guide from 3148 was installed in the
34641 body. See front locomotive.
The parts used for the rebuild:
| Part number | Qty. | Description | |
|---|---|---|---|
| Front locomotive |
392730 | 1 | Guide for coupler pocket, as on 3464 |
| 292740 | 1 | Coupler pocket, as on 3464 | |
| 7319 | 1 | Contact tongue (Y-shaped) | |
| Rear locomotive |
60901 | 1 | Digital high propulsion conversion set |
| 258820 | 1 | Decoder holder | |
| 392730 | 1 | Guide for coupler pocket, as on 3464 | |
| 392740 | 1 | Coupler pocket, as on 3464 | |
| 7319 | 1 | Current conducting coupler rod |
The double 3148 decoder functions:
| Functions | Description |
|---|---|
| f0-f | Front light end 1, front locomotive, changing with direction |
| f0-r | Front light end 1, rear locomotive, changing with direction |
| f1 | Front Telex couplers on both locomotives |
| f2 | Front light end 1, both locomotives, not changing with direction |
| f4 | Acceleration and braking delay cancelled |
Decoder adjustment:
The speed on both decoders are adjusted to minimum, but fine tuned to give
synchronised speed. This gave 100 km/h at
"full power". Max. speed for Di5 is 60 km/h.
Acceleration and deceleration is adjusted to a stopping distance of approx 50 cm
from 60 km/h.
Light connection:
Because the lights are connected also to f2, two 1N4148
diodes are required on each decoders.
Wiring diagram:
The four diodes are 1N4148.
Screenshot from the Central Station 1:
Left is the 3148A with brake car, right is the 3148BC double traction.
The parts "left over" from this conversion led to two "new" locomotives:
Ex. Märklin 34641, DB 365 709-5, with 3148 chassis
Telex warning light board and the body from 34641. It has Telex and a
Delta 66031 decoder.
Ex. Märklin 37649, DB 360 159-8, with 3148 chassis
This has per today no motor and decoder. I have installed close couplers, so it's possible to use it as an unpowered dummy
locomotive. Maybe I will install a pick-up shoe, an old 6080 decoder and
lamps in it. The decoder will be used to turn the lights on and off.
I found an old roof for this one, as it's black roof is used on another of my NSB Di5