| However the Brushcutter was developed (whether a flash of inspiration, or years of building on existing technology), the product is now one of the mainstays of the Outdoor Power Equipment Industry.
VIP founder Bill Vis attributes a large part of his success to the humble brushcutter. In the late 1970s Bill had just gone back into professional mowing when he saw his first brushcutter. Not that he knew what it was. Like many others, this strange looking engine-on-a-stick puzzled him. But once he saw what it could do he was sold! He immediately began offering his clients a brushcutter edging service for an extra $2.00. That was an immediate 20% increase in his income for an additional couple of minute’s work per job (and with no extra travelling time eating into it). When he began VIP Home Services a brushcutter was an immediate and essential part of every franchisee start-up kit.
However, when buying new equipment it is often difficult to determine which machine is going to be the most appropriate for you. In a labour intensive industry like contracting, careful selection of equipment can significantly reduce the time to perform an operation. As labour charges approach $1/min, a one minute saving means your quotation can be $1 lower or your profit $1 higher.
Below we discuss the key factors you should consider when making your decision. It is advisable that you consult your local OPE Specialist Dealer to assist you.
Vibration
Vibration is becoming a major concern, due to an increase in industrial injuries caused by high vibration levels in the workplace. Health effects are strongly related to the duration of exposure which is prolonged for contractors and may produce musculoskeletal disorders, commonly referred to as Hand-Arm Vibration (HAV) syndrome, that includes tendonitis, white finger disease (Raynaud's Phenomenon) and carpal tunnel syndrome.
 Caption: Vibration is becoming a major concern
HAV exposure may result in a range of health effects collectively known as Hand-Arm Vibration Syndrome or HAVS. The most well known of these is vibration “white finger”, but other effects include damage to sensory nerves, muscles and joints in the hands and arms.
HAV should not be confused with “Whole Body Vibration” (WBV), which is associated with back pain alongside other factors such as poor posture and heavy lifting. WBV risks are associated with commercial/industrial vehicle operation (eg ride-on mowers). Especially when they are driven regularly for most of the day. Vibration from the machinery is transmitted to the operator through the seat or feet.
Most manufacturers have addressed vibration issues and have minimised vibration at the D handle, (although the level at some throttle grips was considered to be too high). The recently introduced four-stroke technology provided an interesting comparison.
Vibration issues are covered in great detail in PEA June 2005, p 24-31
Noise
Exposure to excessive noise causes hearing loss. Like vibration damage can be caused by single exposures to extreme noise emissions and/or by prolonged exposure to raised levels. Noise-induced hearing loss may be temporary or permanent depending on the characteristics of the noise, the duration of the exposure, and individual susceptibility. Other effects of noise exposure may include loss of concentration, lowering of attention, and interference with audible warning signals. Usually temporary losses are restored within 16 hours. Permanent losses are irreversible and cannot be corrected by conventional surgery, therapeutic procedures, or hearing aids.
 Caption: Wearing earmuff is essential as only 90dB(A) for 8-hours a day over a working life produces a hearing loss of 84%!!
According to Standards Australia, exposure to 90dB(A) for 8-hours every day over a 40-year working life produces an expected incidence of hearing loss of a staggering 84%. Exposure to potentially hazardous noises such as OPE operation can contribute significantly to a person's overall Daily Noise “Dose”.
The necessity for effective operator hearing protection is clearly demonstrated as noise levels at the operator’s ear are generally well over the recommended Daily Noise “Dose”. Holding a line trimmer vertically in front of the body (as many do when edging) is not recommended and should be considered bad work practice because of the even closer proximity of the engine to the operator’s ear.
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So, earmuffs should always be worn. They reduce perceived noise level by subtraction (attenuation). A noise of through muffs rated at 21dB(A) is (100 - 21) = 79dB(A). Better quality earmuffs with a rating of 33dB(A) will reduce the perceived noise level to (100 - 33) = 67dB(A).
It should be remembered that even 3dB(A) represents a 50% reduction in noise output because of the logarithmic decibel scale. Hearing protectors will not be effective unless they are worn at all times during exposure.
Engines
In the past, the two-stroke engine has been the industry standard. This is changing, because of emission regulations. In its place are mini four-strokes, hybrid 4-stroke/2-strokes and innovative low-emission 2-cycle designs.
Any system that relies on a constant speed, to achieve satisfactory results, requires the availability of extra power when it is needed, so engine output is critical. The PEA/OPEA Pocket Specifications Guide (distributed with PEA February 2006) contains manufacturers’ factory power outputs for their units (at maximum engine speed). Certainly, you have got to be looking at least a 25cc rating for any professional application; higher if possible. Below this level the machine will be under powered, especially in long, wet grass or thick-stemmed undergrowth. This situation is dangerous and can seriously damage the brushcutter.
Clutches
Some entry-point models have the drive the shaft directly from the engine. This is simply a matter of removing components to reduce costs. While this may not unduly affect operation of product life in light domestic circumstances, in heavy conditions either shaft or engine can be easily damaged when the clutch is removed. A clutch ensures that when an engine is idling, the drive is disengaged reducing the likelihood of contact with a moving cutterhead. It means the engine need not be switched off between sites.
Watch out for throttles that come ‘off adjustment’ so the engine does not slow down sufficiently to stop the blade.
Shafts
 Caption: For heavy work the only answer is a solid straight shaft
A flexible drive-shaft will consist of either a soft steel rod or a wire core encased in a coiled wire sheath. Like clutchless models, this type of drive is generally sufficient for light domestic use. However, they can unwind, or in some cases break, if placed under a heavy load.
For heavy-duty work the only answer is a solid straight-shaft made from high carbon steel. With these units power is transmitted through the angle from shaft to cutterhead is by a bevel gear (which will require ongoing greasing). Straight-shafts and bevel gears will absorb the turning forces that are created, in certain conditions and because there are no joints where stress levels can build-up the chance of a breakage occurring are less likely. The shaft is supported at intervals throughout its length by rubber mounted, brass bushes, which also help to absorb vibration. Another advantage is this type of shaft is that they are longer, so produce a wider cutting arc.
Handles
 Caption: As engine displacements increase most manufacturers shift to "U" or "Bull-horn" handles.
Most domestic units have “D”, “J” or similar loop/semi-loop handles. This is also the case with smaller-displacement professional models. However, as engine displacements increase most manufacturers shift to “U” or “Bull-horn” handles. When a blade is travelling at over 8000rpm, if it comes into contact with something solid the machine is going to take some holding. In addition, they give the operator greater control and more stability on rough ground with an easier swinging action when cutting.
Next Issue: Part III Line Heads, Line Types, Blades & Technique
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