By Lauriston Muirhead
Petrol engines come in two main types – two and four stroke. In a “two stroke” the piston goes up (one stroke) and down (two stroke) to produce one push on the crankshaft. In a “four-stroke” the piston goes up and down and then up and down again – making four strokes to produce one push on the crankshaft.
Two strokes are simple, cheap and light but, because of their simplicity, they are appallingly wasteful and highly polluting. In a two stroke the lubricating oil is mixed with the petrol and so is burnt – producing massive hydrocarbon pollution. In a four stroke lubricating oil is kept largely separate from the petrol and so is not burnt. Both engines convert carbon (petrol), that was safely stored underground in oil deposits, into atmospheric CO2 – adding to our global heating problems.
The answer for your next powered garden tool is: buy electric. Electric motors don’t even have pistons! They have one moving part – the armature – which is spun by magnetic fields. Even commercial contractors are now using battery line trimmers, chainsaws, blowers etc. They charge several batteries overnight and can go all day.
I have converted nearly all my previously polluting garden tools to battery-electric. I have even bought a ride-on zero-turn battery powered mower (EGO from Total Tools) to replace our old John Deere. I am lucky enough to be able to charge it via solar panels so the “fuel” is effectively free and there are zero emissions. There are no difficult, expensive belts to replace – direct electric drive motors power each wheel and the two rotating cutters. There is no oil (or filters) to change/top up etc. Maintenance is almost zero. It is much quieter than the old mower. It uses several batteries in the back which can be used to power other EGO products. It will run for two hours and recharges in about two hours. So far it’s a dream! (I am not receiving anything for this “ad!” Also please do your own research.)
Electric motors convert up to 90 percent of electrical energy into mechanical energy. Even the best petrol motors only convert 30 to 40% of the energy in petrol to mechanical energy because they lose so much energy (as heat) when they burn the fuel. “Go electric!”