I am often asked which is the toughest lawnmower, usually by people who should ideally be buying a flail mower but do not want to spend quite that much.
Lets face it, a lawn by, by nature, should not require a particularly tough machine. But some peoples idea of a lawn is what others would consider to be a field. Some ground. although grass covered is full of stone which keeps coming to the surface. The area around Branscombe and Beer in Devon is particularly bad for this with irregular shaped and very hard flints, whereas the area around Budleigh Salterton and Woodbury is littered with large, but very rounded hard pebbles.
Of course, a rotary blade turning at 3000 RPM is not going to respond well to clouting a hard stone, and damage will ensue. At best the damage will be limited to a blunting of the blade, but cheaper, thinner blades can be distorted by impact. Blades can be easily replaced an can be considered a necessary cost of maintaining rough areas.
Then we need to consider the rest of the machine. Any blade impact will also put a stress on the blade mounting and the crankshaft. Cheaper mowers tend to have their blades mounted direct to the crankshaft via a mounting flange (boss). This boss may have little drive pegs which drive the blade and will be designed to shear under impact requiring replacement as soon as this has happened. Others have friction discs designed to let the blade slip just a little any time the blade impacts, so these would be a better choice for stoney ground.
The whole purpose of having some 'give' in the blade is to prevent the impact from causing costly crankshaft distortion.
More expensive mowers may be fitted with a Blade Brake and Clutch assembly (BBC) and these clutches will offer the very best protection against crank damage.
The actual chassis (deck) of the mower will also take a beating from stones. The cheaper thin steel decks will get dented from stones and distorted, whilst the more expensive Aluminium decks can suffer from cracks if clouted by a flying stone. Plastic decks should be avoided if any stones are present.
So, if you want my advice for the very toughest mower then it would have to be the Kaaz 5360 HXA PRO. View the Kaaz range
This mower is incredibly strong, with a tough blade mounted to a heavy duty clutch assembly. The deck is thick aluminium for rigidity, protected internally by a steel liner to prevent stone damage to the deck. And the mower has large diameter wheels made of aluminium with precision ball bearings. The handlebars can be a weak point on mowers generally so this Kaaz has extra braces to support the handles.
All in all the toughest mower I have ever encountered. I have admired them for many years although I had not sold them until recent years. I am now proud to be a Kaaz dealer and very confident to recomend them as the toughest machines I know.
But a word of warning, even these mowers are not invincible, so try not to hit the stones!