Pushback:
Pushback occurs when the chain on the top of the bar is suddenly stopped when it is pinched, caught or encounters a foreign object in the wood. The reaction of the chain drives the saw straight back toward the operator causing loss of saw control. Pushback fre- quently occurs when the top of the bar is used for cutting (fig. 14).
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To avoid pushback
1.Be alert to forces or situations that may cause material to pinch the top of the chain.
2.Do not cut more than one log at a time.
3.Do not twist the saw when withdrawing the bar from a plunge cut or under buck cut (figures 25 to 27 and 33, pages 13 and 14), because the chain can pinch.
Pull-in:
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WARNING! |
Use extreme caution when cutting small size brush and saplings which may easily catch the chain and pull you off balance.
To avoid pull-in
1.Always start a cut with the chain rotating at full speed and the spike bar in contact with the wood.
2.
Cutting techniques
Felling
Felling is cutting down a tree.
Before felling a tree, consider carefully all conditions which may affect the direction of fall, including:
The intended direction of the fall.
The neutral lean of the tree.
Any unusually heavy limb structure.
Surrounding trees and obstacles.
The wind direction and speed.
WARNING!
Always observe the general condition of the tree. Look for decay and rot in the trunk. If it is rotted inside, it could snap and fall toward the operator while being cut.
Also look for broken or dead branches which could vibrate loose and fall on the operator. When felling on a slope, the operator should stand on the
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When felling in the vicinity of roads, railways and power lines, etc., take extra precautions (see fig. 16). Inform the police, utility company or railway authority before beginning to cut.
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