Low tech shredder gearbox

Just a thought I had: If you wanted to build a larger shredder, if you have an old-style large cement mixer it can form the drive and gearbox for low speed and high torque. You just need a way to attach your shredder axle to the drum of the mixer.
It needs to be the old style mixer with the cog teeth around the outside of the drum, like this one:

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Another low-tech idea I just remembered which I saw in Africa once:
A pair of car wheels mounted on a steel beam in line with each other, about 50mm apart. One on a freewheeling hub, one on a drive shaft through a hole in the beam, which connects to your machine e.g. shredder. The drive shaft needs to be positioned as low to the ground as possible, i.e. dig a hole in the ground for the lower half of the wheel.
Build a small wooden ramp in line with the wheels.
Drive the front wheel of your car up the ramp and over onto the mounted wheels so that it sits between them.
Start the car and run in 1st gear. The differential in the car will send all the power to the raised wheel, in turn powering the drive shaft with very high torque.
Edit to note, it took several people to push the car back down off the ramp afterwards and the whole thing was rather dangerous!