Farish Class 37 wiring

[mr magnolia]

Hi team

 

My loco fleet currently consists of an 04 and a 37 from Graham Farish. Very nice too. Having successfully dismantled the 04 and put it all back together, I then went and did the same with the 37. And it all works again too.

(eventually)

But I was very puzzled by the way the thing is put together - the only way that I can think that the power gets to the motor is by means of the loco body itself, and even then it would seem that it then travels via the PCB sitting on the top.

 

Can anyone let me know if thats right, and is that the norm for locos in N gauge (or any other gauge for that matter)

 

thanks

 

Donald

[Edwin_m]

The metal chassis block is split into two halves, each of which is connected via the bogie pickups to the corresponding rail. This "split chassis" design is used on all Bachmann Farish bogie diesels except the 20 as well as several models in larger scales.

 

New diesels from the 66 onwards, including the 37, still have a split chassis but add the PCB on top. This has a screw on each corner, which not only holds it in place but connects each half of the chassis, hence each rail, to a pad on the PCB. The PCB includes interference suppression and circuits for the lights, and the motor current goes via the DCC socket to the two motor contact strips that descend from near the middle of the PCB down through a slot in the chassis to touch the contacts on the motor itself.

[mr magnolia]

The metal chassis block is split into two halves, each of which is connected via the bogie pickups to the corresponding rail. This "split chassis" design is used on all Bachmann Farish bogie diesels except the 20 as well as several models in larger scales.

 

New diesels from the 66 onwards, including the 37, still have a split chassis but add the PCB on top. This has a screw on each corner, which not only holds it in place but connects each half of the chassis, hence each rail, to a pad on the PCB. The PCB includes interference suppression and circuits for the lights, and the motor current goes via the DCC socket to the two motor contact strips that descend from near the middle of the PCB down through a slot in the chassis to touch the contacts on the motor itself.

 

 

thanks great description of what I had eventually thought, but I'd also thought that it meant that the beast is reliant upon an awful lot of contacts:

rail to wheel

to pickup

to sprung copper bit

to body to screw

to PCB

to PCB motor contactors

to motor.

I'd have gone for a wire, myself! In fact last night after I had reassembled the thing and got it to the stage where the lights came on but the motor didn't go, I spent a good 15mins pondering the fact that there wasn't a wire...

 

If I can ask a supplementary; does the oil gloop that comes as standard issue with the loco interfere in any way with the electricity bits? Can you use a 'dry' spray lubricant in its place that might not pick up so much junk and dust?

 

ta

[David Rickard]

I wired up the contacts on one of my Grafar 168s directly to the DCC decoder I installed; both sides on both bogies are wired. It didn't make a lot of difference! It's a brand-new loco, so it should be pretty clean and working as expected.

 

As mentioned here, it seems to be one of those things that can save time in the long term.

[Edwin_m]

See comments below. I guess they did it this way so it would be assemblable and dismantlable without soldering. In the ones I have (60s and 66s not 37s) the contacts seem pretty reliable except for the pickups that don't always touch the wheels. Also if fitting DCC it is worthwhile insulating the motor contact strips in case they touch the surrounding chassis block.

 

Normal advice is to get rid of excess gloop and use an oil designed for models, applied very sparingly to gears etc using a cocktail stick or similar. Don't oil the motor bearings themselves as the oil apparently gets into the brushes (you'd need to completely strip down to reach this anyway, other oilable places are accessed by removing the bogies). Based on this a spray lubricant doesn't sound like a good idea.

 

thanks great description of what I had eventually thought, but I'd also thought that it meant that the beast is reliant upon an awful lot of contacts:

rail to wheel

to pickup

to sprung copper bit - I think this is the same piece as the pickups so no contact involved.

to body to screw

to PCB

to PCB motor contactors - these are soldered to the PCB so again no contact involved.

to motor.

I'd have gone for a wire, myself! In fact last night after I had reassembled the thing and got it to the stage where the lights came on but the motor didn't go, I spent a good 15mins pondering the fact that there wasn't a wire...

 

If I can ask a supplementary; does the oil gloop that comes as standard issue with the loco interfere in any way with the electricity bits? Can you use a 'dry' spray lubricant in its place that might not pick up so much junk and dust?

 

ta