Robot mowers on slopes what the gradient ratings mean.
Every robot mower publishes a maximum gradient, usually as a percentage. It is the specification most likely to cause a bad purchase, because people compare it against their average slope rather than their worst one.
A mower that handles ninety percent of a lawn and gets stuck on the remaining ten is a daily annoyance, not a labour saver.
LUBA 2 AWD 5000
The one built for slopes
All-wheel drive is the specific answer to gradient, and it is the difference between a mower that climbs a bank and one that spins its wheels on wet grass halfway up.
Husqvarna Automower 430X NERA
Proven on uneven ground
A long track record on real gardens rather than flat test lawns. For awkward terrain, that history is worth more than a headline specification.
How to read a gradient rating
Ratings are given as a percentage, not degrees. A forty-five percent slope is roughly twenty-four degrees, which is steeper than most people picture.
Measure your steepest section rather than the overall fall of the garden. The mower has to manage the worst part of its route, and a short steep bank is enough to defeat a mower rated for your average.
Wet grass changes everything
Published ratings assume reasonable traction. Wet grass, moss and leaf litter all reduce it, and a mower comfortable on a slope in July can slip on the same slope in October.
If your slope faces north or stays damp, treat the published figure as optimistic and leave a margin. All-wheel drive buys most of that margin back.
What happens when it cannot cope
Usually it stops and reports an error, which is the good outcome. Less good is wheel spin that tears the turf, leaving bare patches exactly where the grass was already struggling.
Repeated spinning on the same spot is the most common way robot mowers damage a lawn, and it is a sign the gradient is beyond the machine rather than a setup problem to tune away.