A model of a 2 speed capstan. Once again planetary gears are involved. I'm surprised how ubiquitous they seem to be.
The output ie that which the rope to be hauled is wrapped around, is represented by the planet carrier.
For high speed winding disengage the pawl and wind in a clockwise direction. Engage the pawl and the speed goes down and the torque goes up.
Or, to get a pleasing clicking sound from the pawl and high speed (reversed) winding, turn in a counter clockwise direction.
Short video here: http://youtu.be/yJSMlenLgec
Designed in MOI, made in Diamond Age PLA on and Ultimaker 1

It's a while since I made this but I don't recall any special requirements. I normally use 1.2mm walls, 20% fill and 0.2mm layer heights at 200C.
I used Diamond Age PLA.
Do take care with orientation in your slicer as some parts are sure to need laying down or turning upside down.
I have a box of springs and one fitted nicely but a rubber band woud do just a well.