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Flail Mower vs Brushcutter - Which is the best option?

Flail Mower vs Brushcutter - Which is the best option?

The mowing of long grass is a demanding task which can be both time consuming and expensive if the wrong machine is selected to undertake the task. Traditionally this type of mowing would have been undertaken with a large 2-stroke cow horn handled Brushcutter with the operator working slowly across the site, leaving swaithes of cut grass very much like a scythe. This is a slow process and a hard-manual task which when working on a steep slope has an increased risk of injury to the operator.


As a result, machinery manufacturers’ sought to develop specialist mowers that would increase the productivity of the mowing operation, improve the quality of cut and look of the mown grass, and make the whole operation less challenging for the operator. Recent changes to mowing practices where many areas are now left uncut to allow wildflowers to grow and seed has also expanded the demand for this type of equipment.


There are two principle types of machine that have been developed to undertake the mowing of long grass and steep slopes where a normal mower simply cannot cope with the volume of material being cut:

Brushcutters – Cut the grass horizontally with a large rotary blade, and sometimes a second mulching blade mounted above it to help reduce the volume of cut grass that is discharged either to the side or rear of the machine.

Flail Mowers – Cut the grass vertically by mounting a series of small blades (known as flails) on a rotor which are rotated at high speed. The draft created helps to stand up the grass with each individual flail cutting a small area of grass as the rotor revolves with the material being discharged behind the machine.

Specialist manufactures such as AS Motor have many years’ experience in the mowing of long grass and steep slopes and have developed multiple solutions to cope with differing customer requirements. These include pedestrian and ride on brushcutters and flail mowers as well as machines with remote control functionality for extreme slopes or areas of gorse or bramble which can be particularly unpleasant to mow for the operator.


So, the question is which one is right for my application?


To an extent this is a matter of personal preference although there are several factors which will influence your choice. 


The most important one of these is the site to be cut. Do you know the ground you are about to cut? Are there any rocks or tree stumps that protrude from the surface of the ground? If the answer to this question is you don’t know, or you want to cut multiple sites of unknown heritage where there may be building debris or refuse dumped then in this instance, like many hire companies you should consider a flail mower, where the individual blades will swing backwards on impact with a hard surface reducing the chances of serious damage to the machine.


This doesn’t mean that a brushcutter will not work in this environment, simply that the operator must take greater care when mowing unknown areas and be ready to raise the mowing deck quickly or stop cutting should the need arise. To help mitigate the risk of machine damage, manufactures have added protection to the brushcutter drive with heavy duty spindles, shear bolts and in some instances swinging tipped blades that swing back on impact.

The second factor to consider is speed of operation, flail mowers tend to be able to clear sites quicker than Brushcutters especially in long grass as they can quickly clear the cut material whereas with a Brushcutter it may be necessary to slow the forward speed of the machine slightly to allow the cut material time to discharge.


In terms of the quality of cut you require, both flail mowers and brushcutters are capable of leaving a clean cut finish. Brushcutters tend to leave the cut material in rows, while flail mowers discharge cut material across the full width of the machine.  Due to cutting vertically a flail mower tends to work best when cutting to a lower height of cut than a brushcutter as it is the lower part of the plant being cut that provides greater resistance for the blade to cut against. A floating flail deck can also follow the contours of the ground more easily than a brushcutter where its larger rotary blade can scalp the surface being cut where the ground undulates excessively.


If possible, leave some length in the uncut material then if you are using brushcutter with a mulching blade fitted, such as the AS Motor 940, where some of the cut material is pushed down into the surface of the uncut grass to decompose naturally back into the soil it, is possible to achieve a very clean finish to the mown grass.


Given the nature of the job it is important that regular service and maintenance is undertaken, blades need to be kept sharp and when worn replaced, rotary brushcutter blades tend to be quicker and easier to sharpen and replace and generally are less expensive than a full set of flails, although if a flail is damaged by impact it’s a simple job and inexpensive to replace.


For either machine it is important to ensure that grass and other debris does not become trapped in the machine as this will put additional pressure on bearings and result in premature failure and potentially an expensive repair.


In summary, both flail mowers and brushcutters are capable of cutting long grass and if you are unsure as to which suits your needs best I would certainly recommend speaking to a specialist dealer and consider an on-site demonstration. However, as a general rule flail mowers are more suitable for working in heavy woodland areas and roadside verges which contain hidden foreign objects such as tree stumps or bricks while rotary brushcutter mowers are more suitable for orchards and parkland areas and lighter woodland work where a neater finish is desirable.