Technical M
owing slopes safely can present a headache for today’s turf maintenance professionals. With the advent of more stringent health and
safety legislation, gone are the days of using a hover mower on a rope as an acceptable solution to mowing a steep slope. If nothing else, this method is very labour intensive, quite apart from the potential safety issues. To understand the issue with more
clarity, first let’s clarify what a steep slope is. We could say steep is something that is unsafe to walk across but, at best, that’s a bit vague and certainly not measurable in a defined way. Mower manufacturers who design machines to comply with CE self certification will, amongst other standards, be guided by BS EN 836 Garden Equipment - Powered Lawnmowers - Safety. This, perhaps surprisingly, covers all mowers from small domestic machines up to, and including, the largest professional ride- ons. This British Standard provides clear guidelines for the mower manufacturer when designing equipment. All manufacturers must show the ‘Safe
Working Angle’ on their mowers. To define this, the machine is tipped on a tilt table until at least one wheel loses contact with the ground. At that point, the angle of the slope is measured. Let’s say it reaches a tipping angle of 32° before a wheel leaves the ground, then the safe working angle, as declared by the manufacturer, will be 50% of that, which is 16°. To ensure that this is a true reading, the tipping angle will have been determined with the machine in its least advantageous position, which could be facing down the slope, mower deck or cutting units raised, low on fuel and the operator in the most forward seat position. From this, you can see that a 50% safety margin is built into the standard.
It’s worth noting that this standard does not apply to machines designated as tractors; in that case the
operator/owner must determine what is safe.
If 16° is the safe working angle of a hypothetical machine, how does the operator know when that angle has been reached or exceeded? In truth it can be very hard to judge, especially when driving at speed and concentrating on mowing grass. Further questions arise. Is 16° steep? What does it look like? And, more importantly, what does it feel like? We can try to show what it looks like with a diagram.
This diagram shows what it looks like, but even that is hard to relate to an actual slope. What 16° actually feels like is even harder to depict. How is the operator supposed to judge what is safe and what is not? Some rely on experience. However, many local authorities, municipalities and contractors have measured slopes they have to cut and, in some cases, ban operators from mowing such areas with a ride-on, unless the machine is specifically designed for the purpose. Often, only small areas of a slope are too steep, so how is the operator supposed to know that? Even with all the knowledge available, can it be consistently adhered to? The Health & Safety for England (HSE) advises that “as far as reasonably possible” operators of machinery should mitigate against risk.
A simple ball gauge in a tube or dish can give an approximate indication of machine angle. It is only informative, not proactive. This is where technology can now help, but the primary prerequisite is that the machine in question must be electronically controlled, i.e. the interaction between
Ransomes Parkway 3
“What 16° actually feels like is even harder to depict. How is the operator supposed to judge what is safe and what is not?”
APRIL/MAY 2012 PC 115
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