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ICFR – Chainsaw Safety and Operating Handbook

11.5

ebrAnching

quAlity

The product will influence the quality required. The

following are applicable:

•

Remove branches up to the point of utilisable

timber.

•

Debranch according to prescribed log

specifications.

•

Comply with slash management prescriptions.

11.6

ebrAnching

techniqueS

11.6.1

eVer

method

In this method the chainsaw is used as a lever, with

the chainsaw body either resting against the stem or

the operator’s leg as much as possible. This method is

very useful for debranching trees with symmetrically

placed branches.

Pulling and pushing chains are used in debranching.

Pulling refers to cutting with the under side of the guide

bar, while pushing refers to cutting with the top side.

Note the stance (photo 16) with the feet well apart.

Rest the saw against the stem. Flex the knees. The

same stance is used for all six steps of the debranching

sequence.

Photo 16: Stance

Step 1 – branch 1 – far-side upwards

Cut the branch from below using the top of the guide

bar. The chainsaw under carriage is rested on top of the

stem and moved through branch 1 as a pendulum using

leverage. After cutting branch 1, lean the chainsaw

against the stem.

Step 2 – branch 2 – top side across and towards

the operator

Pull the chainsaw across the stem with the guide bar

resting on the stem. Cut using the top of the guide bar,

leaning a little outwards with the legs and the right

arm supported on the right leg. Beware of kickback.

Step 3 – branch 3 – nearside downwards

Rest the rear handle against the right thigh. Cut the

branch or branches on the nearside going downwards

with the bottom of the guide bar. Let the chainsaw

rest on and as close to the side of the stem as possible.

Do not walk forward as the chainsaw is now on the

operator’s side of the stem. Beware of kickback.

Step 4 – branch 4 – nearside upwards

Move the chainsaw forward using the left knee or

thigh, keeping the left foot in the same position. The

chainsaw rests on that knee or thigh and the top of the

guide bar is used to make the cut. Do not walk forward.

Beware of kickback.

Figure 38: The lever method

Summary of Contents for Chainsaw

Page 1: ...South African Chainsaw Safety Operating Handbook January 2000 ...

Page 2: ...Scottsville 3209 Pietermaritzburg SOUTH AFRICA Telephone 27 33 386 2314 Fax 27 33 386 8905 www icfrnet unp ac za No part of this document may be reproduced or transmitted in any form or by any means electronic or mechanical including photocopying recording or by any information storage and retrieval system without written permission from ICFR ...

Page 3: ... tools 9 4 1 Personal protective equipment 9 4 1 1 Safety helmets 9 4 1 2 Eye protection 9 4 1 3 Hearing protection 9 4 1 4 Gloves mitts 9 4 1 5 Leg protection 9 4 1 6 Footwear 10 4 2 Other equipment and tools 10 5 General safety requirements 10 6 Transportation 11 6 1 Transporting a chainsaw by vehicle 11 6 2 Carrying a chainsaw 11 7 Starting the chainsaw 12 7 1 On the ground 12 7 2 Standing star...

Page 4: ... 11 2 Specialised techniques 24 10 11 2 1 Large trees with a diameter more than the guide bar length 24 10 11 2 2 Large trees with a diameter double the guide bar length or more 24 10 11 2 3 Small trees that lean the opposite way to the felling direction 24 10 11 2 4 Trees that lean at a sharp angle towards the felling direction 25 10 11 2 5 Trees that lean away from the felling direction 25 10 11...

Page 5: ...3 11 4 2 Working stance 33 11 5 Debranching quality 34 11 6 Debranching techniques 34 11 6 1 Lever method 34 11 6 2 Debranching thick branches 35 12 Cross cutting 36 12 1 Introduction 36 12 2 Factors influencing productivity 36 12 3 Safety requirements 36 12 4 Cross cutting quality 36 12 5 Cross cutting techniques 36 12 5 1 Tension on the upper side 36 12 5 2 Tension on the lower side 37 12 5 3 La...

Page 6: ... Sharpening errors 47 14 1 10 Replacing chain links 47 14 2 Guide bars 48 14 2 1 Guide bar design 48 14 2 2 Types of guide bars 49 14 2 3 Guide bar care 49 14 2 4 Guide bar maintenance 49 14 2 4 1 Dressing guide bar rails to remove burrs 49 14 2 4 2 Opening the groove 50 14 2 4 3 Replacing the sprocket 50 14 2 4 4 Replacing the replaceable nose 51 14 3 Chain drive sprocket 51 14 3 1 Construction a...

Page 7: ...ng to the safe operation of the chainsaw ensuring that the user understands the reason for certain mechanical and dynamic principles and reactive forces that exist The Handbook is based on South African conditions with the emphasis being on the chainsaw operator The primary purpose of the Handbook is to make chainsaw operations more efficient and safer The Handbook has been designed to standardise...

Page 8: ...chainsaw Section 8 Describes reactive forces kickback pull in and pushback and ways to avoid or minimise them Section 9 Describes the way in which the chainsaw must be held and the proper stance during cutting The different cutting actions down cut upcut and bore cut are also addressed Section 10 Provides information on felling The following is included factors influencing productivity felling dir...

Page 9: ...the precautionary measures contemplated in paragraphs b and d or any other precautionary measures which may be prescribed have been taken g taking all necessary measures to ensure that the requirements of this Act are complied with by every person in his employment or on premises under his control where plant or machinery is used h enforcing such measures as may be necessary in the interest of hea...

Page 10: ... The cylinder top cover protects the operator from engine heat and noise and assists with the cooling of the engine as chainsaws are air cooled 2 Front handle The front handle is situated at the front of the chainsaw for the operator s left hand It is normally slightly angled and of the correct diameter to ensure a comfortable grip 3 Chain brake lever front hand guard The chain brake is designed t...

Page 11: ... tensioner could be fitted in a different position on the chainsaw depending on the make and model Chainsaw makes models fitted with inertia activated chain brakes are considered safer to use especially when making horizontal felling or bore cuts or when debranching in working situations where the chain brake may not be activated manually The front hand guard also protects the operator s hand from...

Page 12: ...anner scrench is an essential tool for basic maintenance 26 Manuals The manufacturer operator and user manuals contain valuable information that must be studied 27 Anti vibration vibration dampening system Most modern day chainsaws have some form of anti vibration system to lessen the effect of engine and cutting vibration to the operator s hands Normally the engine and cutting section of the chai...

Page 13: ...en chainsaws are exposed to 3 HEALTH HAZARDS The major health hazards associated with chainsaw use that the operator must be aware of are the following 3 1 Exhaust fumes Exhaust fumes contain carbon monoxide which can cause drowsiness and lack of concentration thereby increasing the risk of an accident The muffler has been designed to direct exhaust fumes away from the operator thus reducing the r...

Page 14: ...tal 72 28 Notes to Table 2 All chainsaw operators were equipped with personal protective equipment and all chainsaws were fitted with safety devices Most accidents occured between 10 00 and 11 00 Statistics show that trained and experienced chainsaw operators had less accidents To minimise the risk of these injuries adhere to the following Ensure that all chainsaw operators are adequately trained ...

Page 15: ...ed to deflect or stop small particles such as wood chips However the visor will not completely prevent fine particles from penetrating the eye Adhere to the following Replace when damaged or as per manufacturer s instructions Maintain and clean when required 4 1 3 Hearing protection Hearing damage caused by exposure to continuous loud noise can be reduced by using hearing protection Earmuffs or ea...

Page 16: ...ors may only operate under direct supervision of a competent person Do not attempt tasks not trained for Use only safe working methods and techniques as stipulated in this Handbook Follow all safety requirements as stipulated in this Handbook Use a suitable chainsaw for the task at hand Do not modify the chainsaw from its original design without the manufacturer s permission Use a serviceable prop...

Page 17: ...ide bar facing forwards Carry the chainsaw on the hip with the left hand and the guide bar facing downwards Ensure that the chain and guide bar cover is fitted Photo 1 Carrying a chainsaw on the hip When the chainsaw is running and needs to be carried over shorter distances e g walking from tree to tree in felling debranching and cross cutting operations use any of the following methods Carry the ...

Page 18: ...to 3 Starting on the ground standing Photo 4 Starting on the ground kneeling 7 2 Standing start This method is not recommended for starting large capacity chainsaws or chainsaws with long guide bars Use the following procedure Remove the chain and guide bar cover Ensure the manufacturer s instructions for starting the chainsaw are adhered to Place the left hand securely on the bend of the front ha...

Page 19: ...ctor in the occurrence and force of the kickback reaction Some guide bar and saw chain types are designed to reduce kickback forces Kickback can be minimised and the severity reduced if the following are adhered to Avoid cutting with the upper quadrant of the bar nose Hold the chainsaw firmly with both hands and maintain a secure grip Ensure that the left thumb is around and under the handle Be aw...

Page 20: ...th hands and maintain a secure grip Ensure the left thumb is around and under the handle Always start a cut with the chain rotating at full speed Prevent pull in by using wedges to keep the cut open Cut only one log at a time Be alert to forces or situations that may cause a pull in situation 8 3 Pushback The reactive force when cutting with the top of the saw chain tends to push the chainsaw back...

Page 21: ...arms slightly to improve control of the saw Stand to the side of the intended cut to lessen the chance of injury from kickback Photo 6 Holding the chainsaw Bend the knees or even rest on a knee when using the chainsaw in a low position thereby keeping the back straight This will reduce strain on the back 9 2 Cutting actions Important Always cut at full throttle 9 2 1 Down cut The bottom part of th...

Page 22: ...t Start the bore cut by using the bottom portion of the nose of the guide bar and then the upper portion as the cut proceeds Proceed as follows Step 1 Using the lower tip of the guide bar cut until the guide bar tip is completely buried in the wood Step 2 Align the chainsaw towards the horizontal with the chainsaw at full throttle Step 3 Still at full throttle press the guide bar straight into the...

Page 23: ...e Felling layout Slope Lean of tree Obstacles in the felling path Weather conditions Environmental considerations riparian zones and other special management zones Silvicultural requirements slash management re establishment 10 4 Entering felling zones The felling zone refers to the part of the stand where felling is taking place All personnel must wear the required personal protective equipment b...

Page 24: ...ng aids used in South Africa are felling levers and wedges 10 6 2 Felling levers The felling lever is commonly used when felling smaller trees in clearfelling but is vital in thinning operations There are various models with varying handle lengths When using felling levers Remove the bark where the felling lever will be inserted so as to ensure sufficient leverage Ensure that the felling lever is ...

Page 25: ...causing breakage in these areas When felling downhill on steep slopes the tree gathers momentum with every degree it travels through the felling arc In the case of level ground it moves through 90 whereas on a downhill slope this is greater The likelihood for breakage is thus greater on slopes and consideration should be given to felling parallel to the contour 10 7 3 Tearing at the stump and spli...

Page 26: ...es tops or debris that could fall into the work area when the tree is felled Check for branches interlocking with other trees These could break off as the tree falls and drop into the work area pull the tree away from the desired felling direction or cause other trees to uproot or fall Check for vines that could affect the felling direction Check for any rot where the felling cuts are to be made a...

Page 27: ...the sight line on the chainsaw lined up with the intended felling direction If there is no sight line use another straight edge which is at a 90 angle to the guide bar Ensure that the chainsaw is securely lined up before proceeding with the top cut of the directional notch Figure 11 Lining up the chainsaw With larger trees it may be necessary to stand to the side of the tree when making the top cu...

Page 28: ...o any one side 10 10 2 Position when making the felling cut The felling cut for smaller trees is normally made whilst in the same position as for the top and bottom cuts of the directional notch Beware of your legs when the chainsaw is brought around to the back of the tree to start with the felling cut Photo 14 Felling position for felling cut smaller trees Normally with larger trees it is necess...

Page 29: ...e operator is ready to make the first cut to fell the tree Only felling techniques that have been assessed as being safe may be used Techniques used will depend on the characteristics of the trees to be felled and the felling direction required Modify the standard technique if the trees Have a one sided crown or a significant lean Are leaning in a direction opposite to the desired felling directio...

Page 30: ...right hinge width is reached Before making the swing part of the felling cut saw back about the width of the guide bar That way the hinge will not be severed Step 4 Make the swing cut being careful not to saw the hinge on the other side If required use felling aids before the felling cut is completed Refer to Section 10 11 3 Figure 14 Diameter up to double the guide bar length 10 11 2 2 Large tree...

Page 31: ... chainsaw out of the tree Step 3 Saw off the heel from the rear Be ready to move out of the way of the tree quickly when it beings to fall Important Don t stand directly behind the tree Figure 17 Lean at a sharp angle towards the felling direction 10 11 2 5 Trees that lean away from the felling direction This technique can be used to fell trees that lean obliquely away from the desired felling dir...

Page 32: ...on Refer to section 10 13 Wedges should be used in the following situations 10 11 3 1 Felling large trees with no or slight lean This technique can be used where the diameter of the tree exceeds the guide bar length The wedge will ensure that the desired felling direction is achieved Use the following method Step 1 Make the directional notch as for the standard technique Step 2 Select the side of ...

Page 33: ...ut the width of the guide bar Step 4 Continue with the first part of the felling cut Place a wedge in the cut Step 5 Saw the second part of the felling cut allowing for a wider hinge Tap the wedge in as the cut proceeds Always finish the second part of the felling cut on the safe side of the tree Step 6 Drive the wedge home when the cut has been completed Figure 23 Felling in variation of natural ...

Page 34: ...m cuts of the directional notch have been made to deep leaving no hinge The tree will fall without control c A felling cut overcut may result in the wrong felling direction and guide bar damage d A felling cut too far below the bottom cut of the directional notch reduces accuracy and control e A felling cut made too far above the bottom cut of the directional notch reduces accuracy and control Fig...

Page 35: ...erson performing the task using a canthook or something similar Keep the back straight If the tree is large or jammed hard against the other tree a longer handle on the canthook or a turning strap can be used Figure 27 Rolling the hang up 10 12 3 2 Levering or pulling the hang up The hang up can be levered away from the direction of lean using a sufficiently strong pole until the tree falls to the...

Page 36: ... to work or stand in the bight of an operating rope Figure 31 In the bight of an operating rope Only use recognised methods of machine assistance Never allow machinery or people within two tree lengths of the trees being felled in case there is a mishap and the trees fall in another direction to that planned Machinery is however allowed closer than two tree lengths if the methods in 10 13 3 2 are ...

Page 37: ...an effective means of communication This may require the use of an intermediate person in some circumstances Use sound stumps of sufficient size as anchors Do not use standing trees as anchors Use strops of 1 5 times the SWL of the pulling rope Notch anchor stumps to ensure the pulling rope does not come off Use machines of sufficient weight and winching power to ensure that the tree to be felled ...

Page 38: ... the hazard the risk zone under and around the tree must be clearly marked and all personnel excluded from the risk zone until the tree has been brought down Never move forward within two tree lengths of the cut up tree except where the second lot of cuts are made as described below The following methods can be used to bring down a cut up tree If a machine is present it can assist to push the tree...

Page 39: ...d compression Watch out for spring back Do not cut branches with the tip of the guide bar as it could cause kickback Do not allow the tip of the guide bar to make contact with uncut branches supporting logs butt ends or other obstacles as it could cause kickback Maintain a firm grip on both handles of the chainsaw Do not reach across the guide bar in order to move loose branches Run the saw chain ...

Page 40: ...de upwards Cut the branch from below using the top of the guide bar The chainsaw under carriage is rested on top of the stem and moved through branch 1 as a pendulum using leverage After cutting branch 1 lean the chainsaw against the stem Step 2 branch 2 top side across and towards the operator Pull the chainsaw across the stem with the guide bar resting on the stem Cut using the top of the guide ...

Page 41: ... that may pinch the guide bar due to their weight or tension that has been put on them These branches may first need to have the tension removed by an opposite cut before reverting back to the underside If underside debranching cannot be done as part of the integral debranching sequence turn the stem over with a felling lever canthook or other suiable tool after the large branches have been cut an...

Page 42: ...tension The stem springs upwards Use the following procedure Step 1 Make a cut upwards for about 1 3 of the log diameter or until the cut begins to pinch the guide bar Remove the guide bar with the saw chain at full speed 12 CROSS CUTTING 12 1 Introduction Cross cutting is the practice of cutting a debranched stem into suitable log lengths Cross cutting can take place either infield at the landing...

Page 43: ... 3 Lateral tension Where the log is under lateral tension it is important for the operator to stand on the inside of the curve the compression side when cutting since the stem can easily snap outward after the cross cut As described previously always start the cut on the compression side the inside of the curve Figure 42 Lateral tension 12 5 4 Butting of a rootplate Storm damaged trees that have t...

Page 44: ...Log falls down saw is free Figure 46 Hints to reduce pinching A similar situation can occur as sections are cut off the tree until the rootplate counterbalances the tree and springs back into its original position Figure 45 Cutting of sections Make every effort to put the root plate back in place once the stem has been severed preferably using a machine or a winch to pull it back Warning Never all...

Page 45: ...the crown is resting on the ground but is still attached to the vertical stem the following procedure must be used Cut away the crown tip working in towards the upright stem up to shoulder height Use a canthook to twist the broken crown off Always stand on the opposite side of the intended fall and never pull the broken crown towards yourself Should this not work the broken crown should be pulled ...

Page 46: ... bar and chain drive sprocket Production results obtained with a chainsaw depend on the following factors The competence of the operator The endurance and fitness of the operator Selection of the correct chainsaw including the cutting attachment for the task Condition and maintenance of the cutting attachment The saw chain is the component which does the actual cutting and could have the greatest ...

Page 47: ... top plate the side plate and depth gauge The cutting edges are on the front faces of the top plate and side plate i e the side plate cutting edge is vertical while the top plate cutting edge is horizontal and slopes to the rear The front bottom part of the cutter is the toe and the rear bottom part is the heel The rivets which hold the chain links together pass through the rivet holes Figure 51 P...

Page 48: ...unges into the wood as the chain moves forwards Figure 56 Chip removal top plate cutting edge Once the top plate cutting edge has gone so far into the wood that the depth gauge touches the bottom of the cut it levels out and continues running parallel to the bottom of the cut It is at this point that chip removal takes place The depth gauge setting thus determines the thickness of the chip removed...

Page 49: ... of the bar requiring the chain to be retensioned Chain tension should be checked at frequent intervals in normal working conditions 14 1 7 Running in the saw chain The chain should be submerged in chain lubricant overnight before use The chain requires a certain initial period after start up for the individual components to bed in This period is known as break in or running in The break in time f...

Page 50: ...uality of the lubricant is vitally important for the efficiency of chain lubrication and thus the life of the cutting attachment In addition to good lubricating properties chain lubricant must have the following characteristics Good adhesive properties to ensure that the minimum of lubricant is thrown off the cutting attachment by centrifugal forces Ahigh flash point to ensure that it cannot be ig...

Page 51: ... normal applications is 25 30 as specified by the manufacturer Wider filing angles increase cutting performance in softwood Narrower filing angles ensure a smoother running chain and less vibration in hardwood The side plate angle and top plate filing angle have a significant influence on the chain s ability to cut wood and therefore it is essential to maintain the specified values The depth gauge...

Page 52: ...rer Figure 65 File holder held horizontally Sharpen all cutters on one side of the chain first File from the inside to the outside of each cutter Then repeat the process for cutters on the other side of the chain Filing must be performed on the forward stroke only The file must be lifted off the cutter on the backstroke To achieve smooth faces and sharp cutting edges it is necessary to file evenly...

Page 53: ... with hard materials metal stone etc has a destructive effect on the chain links concerned Errors in sharpening and incorrect chain tension can also cause damage to individual links Badly damaged cutters cannot always simply be filed back because they would then be much shorter and lower than the other cutters They must be replaced like any other faulty links There are several methods of repairing...

Page 54: ...ics are used to select and define a guide bar The guide bar tail assigns the guide bar to specific chainsaw models The tail is characterised by the contour of the tail itself the shape and position of the slot for the mounting studs and the position of the chain lubrication inlet and fixing holes Figure 71 Guide bar tail The groove width refers to the inside width of the groove that must match the...

Page 55: ...g on high powered heavy duty chainsaws Figure 76 Replaceable sprocket nose guide bar Solid nose guide bar These bars and are sometimes called stellite tip bars and are made in a single piece from specially formulated steel Their great resilience make them highly resistant to flexing stresses and warping The rails are hardened and the highly stressed nose area is stellite tipped Figure 77 Solid nos...

Page 56: ...4 3 Replacing the sprocket The sprocket must be renewed if its teeth are worn or the roller bearing is damaged To remove the sprocket first knock out the countersunk rivets This is done by drilling away the heads of the rivets with a drill about 0 5 mm diameter larger than the rivet head and knocking out the rivets with a punch Figure 80 Knocking out the rivets The sprocket assembly can now be pul...

Page 57: ...ame level Figure 84 Filing down projecting rails 14 3 Chain drive sprocket 14 3 1 Construction and mechanical function The chain drive sprocket transmits the engine s torque to the saw chain The teeth of the chain drive sprocket transfer the power to the drive link tangs and the chain is propelled around the guide bar Figure 85 Chain drive sprocket with saw chain The sprocket teeth are designed to...

Page 58: ...ls of the rim keep the saw chain in line i e the rim automatically aligns itself relative to the guide bar groove resulting in a smooth running chain and less wear on the guide bar groove entry area and the chain 14 3 3 Sprocket wear The continuous driving action gradually wears the chain drive sprocket and results in the drive link tangs digging into the flanks of the teeth On the spur sprocket t...

Page 59: ...lace and guard against fire hazards Use a can with a suitable spout to avoid spillage during refuelling All fuel holders must be made from static electric resistant material Clean the filler caps and the area around them to ensure that no dirt falls into the tank Remove the fuel filler cap carefully to allow any pressure build up in the tank to release slowly Shake the mixture thoroughly before re...

Page 60: ...ver Chain catcher Muffler On off switch Throttle lockout and control trigger Rear hand guard Anti vibration system Check and clean replace the air filter as per the manufacturer s requirements Check the starter grip and starter cord for wear damage and functioning Clean the air intake slots on the starter cover Check the guide bar saw chain and chain drive sprocket for excessive wear or damage Cle...

Page 61: ...Work An ILO Code of Practice ILO Geneva 12 JONES A T and SMITH R O 1980 Harvesting Windthrown Trees Forestry Commission Leaflet 75 London UK 13 OCCUPATIONAL SAFETY AND HEALTH SERVICE 1995 Safety Code for Forest Operations Part 3 Logging Department of Labour New Zealand 14 OCCUPATIONAL SAFETY AND HEALTH SERVICE 1994 A Guide to Safety in Tree Felling and Cross Cutting Department of Labour New Zealan...

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Page 64: ...ICFR Chainsaw Safety and Operating Handbook 58 ...

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