This unit is small, compact and can be trailer-mounted for road movement. There are three models, with engines from 3hp to 8hp.
The Supersplitter can make a cut every three seconds. It uses a highly effective ram, powered by the engine, to push the log onto a fixed cutting block at the end of the cutting table. The separated log halves fall onto either side and can be quickly repositioned for further cuts. Operation is via a single lever.
It is a very powerful machine and applies full power instantly, rather than progressively. I have seen it successfully split mis-shaped and knotty logs. Basically, if you can lift the log onto bench, the machine will cut it.
Another log splitter you may like to look at is the hydraulic unit from Makita. With a ram force of six tonnes, this splitter takes logs up to 45cm in diameter.