Here's some more photos of the crane drive system. The main gearbox that lifts the jib up and down is a Tamiya 6 speed gearbox kit.
I had a bearing shell laying around, so filled it with car body filler after inserting it through the output shaft of the gearbox. That way, when it set, it's on there for good. It's off center as far as it would go, so it would act as a cam. There's a hinged steel plate that sits on top of it, so as the cam goes around it moves the plate up and down. The pushrod that lifts the crane jib is sitting on top of the steel plate, (which is part of a gate hinge actually). The other little geared motor drives the rotation of the jib, it also has a micro switch under the steel plate, so when the jib is down, it cuts power to that little motor, that way I can't accidentally rotate the jib while it sits in it's cradle. I have to lift the jib up about 10mm before i can get power to rotate it. Well, I thought it was a good idea.
Hopefully the photos will explain it a bit more and it might make sense.
The last photo shows the gear on the bottom of the crane shaft, that comes into contact with the little motor when I slide it in place.
I made little rails so I can Slide the whole unit in and out, in case I have to remove it for maintenance.