Assessments - 4, GPA: 4.5
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4 Is there a risk of kickback? 5 Do the conditions and surrounding terrain affect your safety when working? Two factors decide whether the chain will jam or the log will split. The first is how the log is supported and the second is whether it is in tension. In most cases you can avoid these problems by cutting in two stages; from the top and from the bottom of the log. You need to support the log so that it will not trap the chain or split during cutting. ! If the chain jams in the cut: STOP THE ENGINE! Don’t try to pull the saw free. If you do you may damage the chain when the saw suddenly breaks free. Use a lever to open up the cut and free the bar. The following instructions describe how to handle most types of situation that you will be faced with when using a chain saw. Cutting 1 The log is lying on the ground. There is little risk of the chain jamming or the log splitting. However there is a risk that the chain will touch the ground when you finish the cut. Cut all the way through the log from above. Try not to touch the ground as you finish the cut. Maintain full throttle but be prepared in case the chain snatches. A If it is possible to turn the log you should stop cutting about 2/3 of the way through. B Turn the log and finish the cut from the opposite side. 20 – English SAFETY INSTRUCTIONS 2 The log is supported at one end. There is a high risk that it will split. A Start by cutting from below (about 1/3 of the way through). B Finish by cutting from above so that the two cuts meet. 3 The log is supported at both ends. There is a high risk that the chain will jam. A Start by cutting from above (about 1/3 of the way through). B Finish by cutting from below so that the two cuts meet. Limbing When limbing thick branches you should use the same approach as for cutting. Cut difficult branches piece by piece. 1 2 3 3 Tree felling technique ! ! It takes a lot of experience to fell a tree. Inexperienced users of chain saws should not fell trees. NEVER ATTEMPT A TASK YOU ARE UNSURE OF. A Safe distance The safe distance between a tree that is to be felled and anyone else working nearby is at least 21/2 tree lengths. Make sure that no-one else is in this “risk zone” before or during felling. B Felling direction The aim is to fell the tree in the best possible position for subsequent limbing and cross-cutting. You want it to fall on ground where you can move about safely. The main point to avoid is letting the tree fall onto another tree. It can be both difficult and dangerous to remove a tree in such a position (see point 4 in this section). Once you have decided which way you want the tree to fall you must judge which way the tree would fall naturally. Several factors affect this: Lean of the tree Bend Wind direction Arrangement of branches Weight of snow You may find you are forced to let the tree fall in its natural direction because it is impossible or dangerous to try to make it fall in the direction you first intended. Another very important factor, which does not affect the felling direction but does affect your safety, is to make sure the tree has no damaged or dead branches that might break off and hit you during felling. ! ! During critical felling operations, hearing protectors should be lifted immediately when sawing is completed so that sounds and warning signals can be heard. English – 21 22 – English SAFETY INSTRUCTIONS C Clearing the trunk and preparing your retreat Remove any branches that are in the way. To do this it is best to work from the top down and keep the trunk between you and the chain saw. Never limb above shoulder height. Remove any undergrowth from the base of the tree and check the area for obstacles (stones, branches, holes, etc.) so that you have a clear path of retreat when the tree starts to fall. Your path of retreat should be roughly 135 degrees behind the intended felling direction. D Felling Felling is done using three cuts. First you make the DIRECTIONAL CUTS, which consist of the TOP CUT and the BOTTOM CUT; followed by the FELLING CUT. By placing these cuts correctly you can control the felling direction very accurately. DIRECTIONAL CUT To make the DIRECTIONAL CUT you begin with the TOP CUT. Stand to the right of the tree and cut downwards at an angle. Next make the BOTTOM CUT so that it finishes at the end of the TOP CUT. The directional cut should run 1/4 of the diameter through the trunk and the angle between the TOP CUT and BOTTOM CUT should be 45°. The line where the two cuts meet is called the DIRECTIONAL CUT LINE. This line should be perfectly horizontal and at right angles (90°) to the chosen felling direction. FELLING CUT The felling cut is made from the opposite side of the tree and it must be perfectly horizontal. Stand on the left side of the tree and cut with the bottom edge of the bar. Make the FELLING CUT about 3-5 cm (1.5-2 inches) above the flat section of the DIRECTIONAL CUT. Set the spike bumper in behind the breaking strip (if one is fitted).Use f...
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