A log splitter runs with two main components, the ram and the wedge. The wedge actually rams against the wood, splitting it in half.
The Force Required to Split Logs

Please also see our article on The Janka Scale for more information on the force required to split different types of wood.
Different Types of Log Splitters

Electric Log Splitters 
Electric log splitters are a great choice when you have access to electric power. They are somewhat quieter than gas log splitters. You can also use them indoors, such as inside a barn or a garage, because they don't produce exhaust. You can cut up to 12" logs with the 120V models, up to 24" with the 240V professional grade models. Larger models have the choice of splitting wood horizontally or vertically.
Gas Log Splitters 
Gas log splitters are a great choice for those that want to take their splitter to the wood. You'll be able to tow most of these models, and cut wood from 18-26" depending on which model you select. The larger log splitters allow you to split wood horizontally or vertically, which will make your job a whole lot easier.
Skid Steer Log Splitters
Skid steer log splitters allow you the greatest flexibility because you're able to stand next to it, or stay in your cab while you move from log to log, splitting wood as you go. Choose from 20 or 30 ton models, allowing you to split up to 24-26" green or seasoned wood.
3-Point Log Splitters
3-Point log splitters let you use your tractor's hydraulics and 3-pt. hitch to power your splitter --no separate engine or pump is required. Your tractor will easily haul the splitter to wherever your wood is. These splitters come with all the hardware you need to attach to a Category 1 tractor.