RC Truck and Construction

I am in the loooong process of building on as well. Been working on it off and on for about 2 years. All is done except paint, and reworking the screw drive I started with. I used threaded rod and a nut on the axle carriage, but it takes forever to wind it up and down. I used the same on the lifting 5th wheel plate (for tilt), and it needed the reduction to lift any serious weight so the threaded rod will stay there. I am looking into long linear servos, doubled with an intermediate carriage now. So one servo would connect to the carriage and the frame, the other servo would connect the carriage to the axle dolly. It works as it is now really well, just takes forrrrever to wind the axle carriage up... You might look at a linear servo or long drill bit (some people have used them as jack screw/piston for the dump bodies out there) I might go drill bit, but I am more interested in where linear servos are going, especially as they are getting longer and smaller...