11 September 1998

Chainsaw checks can save your life

Thorough chainsaw

maintenance is essential to

ensure the safe and efficient

operation of these

potentially lethal machines.

Andy Collings explains what

to look for

A GOOD maintenance routine for chainsaws means more than ensuring an efficient cutting performance; operator safety is also important when looking after what is potentially the most dangerous machine on the farm.

The biggest problem with farm chainsaws is that they are used occasionally for dealing with storm damage perhaps or to cut wood for winter fires, and seldom-used equipment easily slips down the priority list for maintenance.

This is a factor Richard Todd has noticed in the training courses he runs for chainsaw operators. Mr Todd is assistant head gardener at Anglesey Abbey, the National Trust property near Cambridge, where he is responsible for chainsaw work ranging from felling to tree surgery on the abbeys well wooded 40ha (98 acres), a job which at one time involved felling more than 4000 diseased elm trees.

He is also a qualified chainsaw instructor for the ATB and is on the Forestry and Arboricultural Safety Training Council register.

"I find it is often the occasional users who tend to be more casual about maintenance, and in my experience that includes farmers and farm workers," says Mr Todd.

"I am sure they look after their other machinery very well, but when you use a chainsaw for only a few days each year it is easy to overlook the routine maintenance."

Keeping the chainsaw working efficiently and safely demands a simple maintenance routine each working day plus a more thorough overhaul which, for an occasionally used farm chainsaw, is probably an annual job for a wet day in the workshop.

Safety plays a brief but important part in the daily maintenance routine. As s soon as the engine is started and has warmed up, the operator can test the chain brake. The test is carried out with the engine at full power, using the hand on the top handle to flick the brake control to on and check that the chain stops instantly.

"The test takes virtually no time at all, but it is very important to carry it out at the start of each days work," insists Mr Todd. "If the brake does not stop the chain instantly, the saw is not safe to use until it is working properly."

Starting the engine for the first time each day is also an opportunity to make sure the chain lubrication is working. While the saw is still on the ground, check for the tell-tale mark caused by oil spray from the fast moving chain.

The main reason why chainsaws lose their cutting performance is because the chain needs sharpening, and this is a job which demands care and the correct tools. The best place to do the sharpening is in the workshop with a vice to hold the bar. Working on hardwood can take the edge off a chain in much less than a day and, instead of trying to sharpen the chain on site, the easy answer is to carry one or two pre-sharpened chains ready to fit.

If outdoor sharpening is necessary, Mr Todd recommends a log spike which is hammered into a suitably firm piece of wood to secure the bar.

Using the wrong file can damage the chain and reduce its performance, and filing at the correct angle and checking the depth gauge marks are also important. If Mr Todd is in any doubt about the correct sharpening process to suit the chain, he checks the number on the chain against data in the Oregon guide book, which provides easy-to-follow guidelines.

After sharpening, the chain should be removed so the metal filings can be brushed or blown away.

Checking chain tension should also be a daily routine, and this is done by pulling the chain along the top of the guide bar with a gloved hand while the saw is securely held on a firm surface and the engine is switched off.

The correct time to check tension is at the start of a working day while the chain is still cold, as tension is affected by the chain temperature. A correctly tensioned chain needs a firm pull, and if the chain moves easily the tension should be increased. Using a saw with insufficient tension can cause excessive wear on the underside of the guide bar, just behind the sprocket, and if this continues over a long period it may mean paying out for a new bar.

Changing or sharpening the chain providea a chance to check the guide bars for wear or damage, a job many operators neglect, says Mr Todd. Movement of the chain raises a burred edge on the guide bars, and if this is not removed with a file, some of the burred metal will eventually fall off leaving an uneven surface.

As part of the annual overhaul, check the guide bar for burring and damage, and make sure the wear on both sides is even. Use a file carefully to leave a smooth, level surface for the chain to run on.

Metal filings and accumulated dirt are removed from the guide bar groove by a special scraper, which can be home made in the workshop. Pull through from the sprocket end of the bar to make sure debris is removed from the groove.

For most lightly used farm chainsaws engine maintenance falls into the annual category, but the air filter is the exception. The high performance engines which power chainsaws are exposed to large amounts of dust and the air filter needs frequent attention, preferably before loss of power and a smoky exhaust show that cleaning is overdue.

Filter cleaning should be done in the workshop at the beginning or end of the days sawing. Put the choke control on before removing the filter, as this helps to keep debris out of the carburettor.

Wash the filter with warm soapy water, and dry it thoroughly before refitting. Blowing out the area around the filter with an air line helps to remove accumulated dust, but block the air inlet hole first.

Lubrication requirements vary between different makes and models, and the makers instructions should be followed. Some saws, including he Husqvarna 254XP used for the maintenance demonstration, have a small grease hole at the nose or sprocket end of the guide bar, and this needs regular checking to make sure it is not blocked with dirt, a point which is often missed. Stihl is one of the makes with a sealed bearing on the nose sprocket which does not need a grease hole.

Even the most rugged and reliable of chainsaws can be let down by a broken starting cord, and some seasoned operators include a spare cord as part of their emergency kit. But Mr Todd says problems can usually be avoided by regularly checking the cord for signs of wear or damage, and the main overhaul is also a chance to make sure the automatic rewind is correctly adjusted and does not leave several inches of loose cord, reducing the cords effectiveness.

An emergency kit should also include spanners and a screwdriver – sometimes combined in a single multi-purpose tool, the correct file and holder for the type of chain used, a log vice and something to hammer it with, plus a grease gun.

And with safety in mind Mr Todd includes two other essentials in his recommended list; a first aid kit and a mobile phone. A mobile phone is not a luxury for a chainsaw operator, he says. It is an essential means of bringing help if there is an accident and with chainsaw injuries prompt assistance could save a life. &#42