Technical
Lee Kristensen is a product manager at Ransomes Jacobsen. He manages the full range of Ransomes ride-on mowers and is responsible for the development of new products, including the recently launched MP series. In this article, Lee discusses the decline in cylinder municipal mowing, and why we shouldn’t abandon the concept altogether.
C
utting grass with cylinders has been the norm for 185 years and, in various forms, has remained a staple of grounds maintenance. Cylinder mowing has been adapted for use
from millimetre precision on the top playing surfaces around the world, to mowing through dense lush growth on roadside verges. At the top end of grounds maintenance,
there is no doubt that cylinder cutting is the only choice, and manufacturers are continuously improving the craft with geometry tweaks, new materials, tighter tolerances and new attachment innovations to keep improving surfaces.
Cylinder mowing has also long been the
leading practice in municipal grounds maintenance in the UK, making our green spaces enviable across the world. This reputation is already fading and, with the ever- increasing pressure on parks and grounds maintenance budgets, it is at risk of being a distant memory. The development of rotary and flail mowers
has met in the middle with the slow decline of expectations, forced by dropping resources, meaning there are strong arguments for these alternatives. These different methods of cutting appear attractive on the surface but, before the whirr of cylinders becomes alien around the streets of the UK, let’s remember what we’re missing. The introduction of the triplex mini flail
format pioneered by Ransomes, and continued development of technically progressive, comfortable, 1.5m out-front rotary and flail mowers has increased the range of viable methods of maintaining municipal turf. How do each compare to triplex cylinder mowing in its established form? The focus of the discussion here will be on
these smaller ride on units, but many of the arguments are still valid when comparing larger area, ride on cylinder mowers and trailed gangs, with their large rotary competitors.
Efficiency: Fuel and labour used to cut grass
Efficiency can be looked at as energy input (fuel and labour), and work output (grass cut). This category is where the old cylinder triplex really shows its strengths. Out-front rotary and flail mowers most commonly have a 1.5m width of cut, with the triplex cylinder and flail mowers at
Lee Kristensen
2.1m. So, in a straight, side-by-side comparison, there is a clear winner. If you factor in the ability of a triplex to lift individual units around street furniture, further advantages become apparent. It is far more likely that operators can continue cutting in one direction without stopping, turning and coming back for the small areas missed. Now, going back to basic principles when
considering fuel use: the scissoring action of cutting grass with cylinders takes the least force and hence less power and fuel. Impact cutting methods of rotaries, and especially flails, are very wasteful; moving lots of air, creating noise whilst tearing the leaf plants through brute force. Case-by-case, fuel usage per square metre of cut grass is going to vary on cutting cycles and machine conditions. As an example, running a 33hp machine constantly in conditions that heavily load the engine can use up to a litre an hour more fuel than in normal use. All of this considered, the efficiency arguments are strongly stacked with the triplex cylinders.
Capability: What can you cut?
Flails are generally regarded as having the widest range of cutting capability. Running a large number of high-quality blades at a high speed, can achieve a very uniform cut. The cutting motion does mean it needs some resistance in the sward to work against and attain this uniform level of finish. If conditions are too light or cutting height is too high, it can be inconsistent. Flails also have the largest unit headspace for moving cut material, which is often the bottle neck when cutting long grass. Rotaries work very efficiently in the middle range, but often choke up in heavier conditions because they haven’t got the space to get rid of the cut material. Side discharging rotaries help with this, but brings its own challenges. The manufacturers’ recommendation on cylinder mowers is that they can’t remove material that sits above the centre line of the cylinder spindle, as it sits in the grass. Any cylinder mower operator under pressure to complete their round will tell you they are capable of much more. The actual capability is a function of many other characteristics. A slightly reduced mow speed, with a large diameter cylinder, and a low
PC AUGUST/SEPTEMBER 2017 I 139
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