converting from dummy back to rapido couplers trick

[conradin]

I got a new B23-7 and it already came with the dummy knuckle couplers.  But it does have a pair of rapidos just in case if you want to revert back to them.  I decided to revert.

As it turns out, it is impossible to revert it if you disassemble and then assemble entire draft gear box in the exact reverse order.  The coupler pocket should be upside down when you try to put it back.  The problem is, while normally you would put in the rapido into the draft gear box and then push it  through the coupler space of the body, it is impossible to do so with the rapido on the B23-7.  The empty slot which the coupler comes through from the draft gear box to the outside of the body (let's call it the coupler body opening) is barely big enough for a dummy knuckle coupler to go through. That is, you cannot put the entire draft gear box assembly through because it is too big for the opening.

Instead of cutting the space and make the coupler body opening bigger to allow the housing to go through, here is the better alternative:

After disassembling the draft gear box and get rid of the dummy knuckle coupler, you can now install the rapido in this order:

1.  Put the coupler pocket on the underside of the body where the coupler cover usually sits.
2.  Put the draft gear spring on the rapido
3.  Push the rapido through the coupler body opening and carefully put it on/in the coupler pocket.  Make sure now the rapido and the draft gear spring sits correctly.  Use a tweezer or your other hand to press the coupler pocket against the coupler body opening to prevent it from falling out of the place where it sits on.  Also, make sure the rapido "trip pin" points down instead of up (ie, it should NOT be facing you).
4. Gently push the coupler pocket assembly away from the coupler body opening, but only for a milimeter.  (ie. one milimeter away from the opening)
5. Now put the coupler cover on top of the coupler pocket assembly.  Now the entire draft gear box with the rapido is assembled.
6. Use a tweezer and gently hold the draft gear box and now turn it upside down 180'.
7. Now you can push the draft gear box back into the spot tight against the coupler body opening (ie. one milimeter towards the opening).
8. Use a tweezer to gently put one screw into the draft gear box, while use another tweezer to hold the it steady.
9. As soon as the screw drops inside the draft gear box, use a small screw driver and screw the screw through the gear box into the body.
10. Check whether the rapido sits correctly and that it has a correct slack.
12. Now screw the other screw into the draft gear box.
13. Double check whether the rapido is working correctly.  If it works, you are done.
14. Now you can repeat the same thing for the other draft gear box.


Summary:  Assemble the entire draft gear box upside down, then turn the entire assembly downside up to its normal position, then you can screw the gear box into the body.

Hope this helps.

[GlennW]

You may try the MTL coupler tweezer to hold the assembled coupler & put it where you want. It's a nifty little tool.

What was wrong with the dummy couplers? Do they mate with anything else? Are they too high/low to be useful? It's very difficult to get any info about the new couplers.

[conradin]

You may try the MTL coupler tweezer to hold the assembled coupler & put it where you want. It's a nifty little tool.

The problem is that you cannot assemble the draft gear box and coupler outside of the car.  You have to assemble it with the coupler box inside the car while the coupler itself outside the car.   
I am a trained watchmaker, so I have plenty of tiny tools.

What was wrong with the dummy couplers? Do they mate with anything else? Are they too high/low to be useful? It's very difficult to get any info about the new couplers.

No idea.  But since all my trains are rapidos, I need to change the engine's dummy knuckle to rapido.