Here is my fully remote controlled Backhoe loader based on the JCB 4CX, which is a Backhoe loader with 4 equal-sized wheels & 4-wheel-steering.
This model features a blend of Pneumatic & power-functions. It has:
* 4-wheel drive
* 4-wheel steering
* V6 engine
* Fully functional front-loader
* Fully funtional backhoe (including sideways-movement)
* Everything (even the lights) are remote controlled by a seperate remote controller.
For years, the 8455 was the standard in Lego Technic Backhoe loaders, but with the presence of the Power-functions system, I know it could be improved. So a specific Backhoe was chosen, in this case the JCB 4CXwhich was to be modelled. This is a Backhoe with 4 equal-sized wheels, which made the choice for the wheels a lot easier. Now the 8297 wheels could be used. And of course the 4-wheel-drive & 4-sheel steering had to be implemented.
For every function both pneumatic & electric systems were considered. Power functions have the advantage to be very controllable, but generally need quite some space and reliable drivetrains. Pneumatics are easier to construct and quite powerful, but are harder to controll.
While examining the 4CX, I noticed that its complete backhoe could move sideways. This was quie a challenge to recreate. A kind of rails was constructed to guide the moving backhoe. The M-motor which was used for the sideways-motion was placed inside the main body, and the M-motor for rotating the backhoe was placed in the first section of the backhoe.
The remote controller houses a compressor, air-pressure-regulator and all the switches for all the functions.