Dolmar PS-351, PS-421, Gasoline Chain Saws PS-421 User Manual

10.44 Mb

Operator’s and Safety Manual

for Gasoline Chain Saws

WARNING!

Read and understand this Manual. Always follow safety precautions in the Operator’s and Safety Manual. Improper use can cause serious injury!

Preserve this Manual carefully!

WARNING!

FUELS WITH MORE THAN 10% ETHANOL ARE NOT APPROVED FOR USE IN DOLMAR 2-STROKE ENGINES! Use of alternative fuels, such as E-20 (20% ethanol), E-85 (85% ethanol) or any fuels not meeting DOLMAR requirements are not approved for use in DOLMAR 2-stroke gasoline engines!

USE OF ALTERNATIVE FUELS CAN CAUSE THE FOLLOWING PROBLEMS:

Poor engine performance, loss of power, overheating, fuel vapor lock, improper clutch engagement, premature deterioration of fuel lines, premature deterioration of gaskets, premature deterioration of carburetors.

USING ALTERNATIVE FUELS AND/OR 2-STROKE OILS NOT ACCORDING TO JASO FC OR ISO-L-EGD IN

DOLMAR 2-STROKE ENGINES WILL VOID YOUR ENGINE WARRANTY!

PS-351

PS-421

EMISSIONS COMPONENT DEFECT WARRANTY COVERAGE

DOLMAR warrant to the initial retail purchaser and each subsequent owner, that this utility equipment was designed, built, and equipped to conform at the time of initial sale to all applicable regulations of the U.S. Environmental Protection Agency (EPA), and that the engine is free of defects in materials and workmanship which would cause this engine to fail to conform with EPA regulations during its warranty period.

For the components listed under PARTS COVERED, the service dealer authorized by DOLMAR will, at no cost to you, make the necessary diagnosis, repair, or replacement necessary to ensure that the engine complies with applicable U.S. EPA regulations.

EMISSION COMPONENT DEFECT WARRANTY PERIOD

The warranty period for this engine begins on the date of sale to the initial purchaser and continues for a period of 2 years.

PARTS COVERED

Listed below are the parts covered by the Emission Components Defect Warranty. Some of the parts listed below may require scheduled maintenance and are warranted up to the first scheduled replacement point for that part.

Fuel Metering System	Ignition System
Carburetor and internal parts	Spark plug
Fuel filter, if applicable	Flywheel Magneto
Throttle stopper, if applicable	Ignition Coil
Choke System, if applicable

Air Induction System	Miscellaneous Items Used in Above Systems
Pre filter, if exist	Fuel hoses, clamps and sealing gaskets
Air filter, Air filter case, Intake manifold
Components with evaporative emissions
Fuel tank, Fuel tank cap

OBTAINING WARRANTY SERVICE

To obtain warranty service, take your engine to the nearest DOLMAR service Center authorized by DOLMAR. Bring your sales receipts indicating date of purchase for this engine. The dealer of service authorized by DOLMAR will perform the necessary repairs or adjustments within a reasonable amount of time and furnish you with a copy of the repair order. All parts and accessories replaced under this warranty become the property of DOLMAR.

WHAT IS NOT COVERED

• Conditions resulting from tampering, misuse, improper adjustment (unless they were made by the service dealer authorized by DOLMAR during a warranty repair), alteration, accident, failure to use the recommended fuel and oil, or not performing required maintenance services.

• The replacement parts used for required maintenance services.

• Consequential damages such as loss of time, inconvenience, loss of use of the engine or equipment, etc.

• Diagnosis and inspection charges that do not result in warranty-eligible service being performed.

• Any non-authorized replacement part, or malfunction of authorized parts due to use of non-authorized parts.

OWNER’S WARRANTY RESPONSIBILITIES

As the engine owner, you are responsible for the performance of the required maintenance listed in your operator’s manual. DOLMAR recommends that you retain all receipts covering maintenance on your engine, but DOLMAR cannot deny warranty solely for the lack of receipts or for your failure to ensure the performance of all scheduled maintenance. As the engine owner, you should however be aware that DOLMAR may deny warranty coverage if your engine or a part has failed due to abuse, neglect, improper maintenance or unapproved modifications.

You are responsible for presenting your engine to the nearest service dealer authorized by DOLMAR when a problem exists.

If you have any questions regarding your warranty rights and responsibilities, you should contact the DOLMAR Warranty service Department at 1-888-OPE-PART or info@dolmar.com for the information.

THINGS YOU SHOULD KNOW ABOUT THE EMISSION CONTROL SYSTEM WARRANTY:

MAINTENANCE AND REPAIRS

You are responsible for the proper maintenance of the engine. You should keep all receipts and maintenance records covering the performance of regular maintenance in the event questions arise. These receipts and maintenance records should be transferred to each subsequent owner of the engine. DOLMAR reserves the right to deny warranty coverage if the engine has not been properly maintained. Warranty claims will not be denied, however, solely because of the lack of required maintenance or failure to keep maintenance records.

MAINTENANCE, REPLACEMENT OR REPAIR OF EMISSION CONTROL DEVICES AND SYSTEMS MAY BE PERFORMED BY ANY REPAIR ESTABLISHMENT OR INDIVIDUAL; HOWEVER, WARRANTY REPAIRS MUST BE PERFORMED BY A SERVICE DEALER AUTHORIZED BY DOLMAR. THE USE OF PARTS THAT ARE NOT EQUIVALENT IN PERFORMANCE AND DURABILITY TO AUTHORIZED PARTS MAY IMPAIR THE EFFECTIVENESS OF THE EMISSION CONTROL SYSTEM AND MAY HAVE A BEARING ON THE OUTCOME OF A WARRANTY CLAIM.

If other than the parts authorized by DOLMAR are used for maintenance replacements or for the repair of components affecting emission control, you should assure yourself that such parts are warranted by their manufacturer to be equivalent to the parts authorized by DOLMAR in their performance and durability.

HOW TO MAKE A CLAIM

All repair qualifying under this limited warranty must be performed by a service dealer authorized by DOLMAR. In the event that any emission-related part is found to be defective during the warranty period, you shall notify DOLMAR Warranty service Department at 1-888-OPE-PART or info@dolmar.com and you will be advised of the appropriate warranty service dealer or service providers where the warranty repair can be performed.

WARNING !

Careless or improper use of this product can cause serious or even fatal injury.

Before operating a chain saw or other DOLMAR products it is important that you read, fully understand and carefully follow the instructions outlined in this operator’s manual. Kickback may cause severe or fatal injury and is one of many potential dangers in operating a chain saw. Kickback and other safety related precautions are described in detail within this operator’s manual. Additional operator’s manuals are available from DOLMAR

POWER PRODUCTS, PO Box 5007,Alpharetta, GA, 30005-5007, USA, Telephone 1-888-OPE-PART or info@ dolmar.com

This product complies with: American National Standard Institute	B 175.1-2000 chain saw safety standard.
Canadian Standards Association	Z62.1-03 chain saw safety standard.
	Z62.3-04 chain saw kickback standard.
Society of Automotive Engineers	SAEJ 335-Jun 95 „Multiposition small
	engine exhaust system fire ignition
	suppression”

The Emissions Compliance Period referred to on the emission Compliance label indicates the number of operating hours for which the engine has been shown to meet federal emissions requirements. Category C= 50 hours, B= 125 hours, and A= 300 hours.

With the purchase of this chain saw you have chosen a German quality product. Important instructions for the assembly and operation of this saw are given in this manual. For your own safety, we ask you to read the accident prevention instructions very carefully before putting your chain saw into operation, as incorrect handling can, despite all precautions, lead to accidents. With a little care and attention you will have good service and lasting satisfaction from this first-rate product.

PS-351, PS-421

Contents	Page
Delivery inventory.....................................................	4
Symbols...................................................................	4
Safety precautions..............................................	5-16
Denomination of components................................	17
Technical data........................................................	18
Only for Models with fastening nuts on the sprocket guard
Mounting the guide bar and saw chain........	19-26
Tightening the saw chain...................................	20
Checking the chain tension...............................	21
Retightening the saw chain...............................	21
Only for Models with QuickSet guide bar...................
Mounting the guide bar and saw chain.............	22
Tensioning the saw chain..................................	23
Checking the chain tension...............................	23
Retensioning the saw chain..............................	23
Models with quick tensioner on sprocket guard...........
Mounting the guide bar and saw chain.............	24
Tightening the saw chain...................................	25
Checking the chain tension...............................	26
Retensioning the saw chain..............................	26
Chain brake............................................................	26
Engaging the chain brake......................................	26
Fuel / Refuelling................................................	27-28

Contents	Page
Chain lubrication....................................................	29
Starting the engine.................................................	30
Stopping the engine...............................................	30
Checking the chain brake.......................................	31
Working in winter....................................................	31
Adjusting the carburetor.........................................	32
Sharpening the saw chain.................................	33-34
Cleaning the brake band and sprocket interior......	35
Cleaning the guide bar...........................................	35
Replacing the saw chain........................................	36
Cleaning the air filter..............................................	37
Replacing the spark plug........................................	38
Checking the muffler screws..................................	38
Replacing the starter cable....................................	39
Replacing the return spring....................................	39
Mounting the fan housing.......................................	39
Cleaning the cylinder area.....................................	40
Replacing the fuel filter...........................................	40
Replacing / cleaning the spark arrester screen......	40
Instructions for daily and periodic maintenance.....	41
Service, spare parts and guarantee.......................	42
Troubleshooting.....................................................	43
Extract from the spare parts list........................	44-45

The PS-351, PS-421 will be delivered in a protective cardboard box to prevent transport damage. Cardboard is a basic raw material and is consequently reuseable or suitable for recycling (waste paper recycling).

Delivery inventory	2	3
Delivery inventory	2	3

1	Chain saw
2	Guide bar	5	6
3	Saw chain
4	Chain protection cover
5	Universal wrench
6	Wrench
7	Screw driver for carburetor adjustment
8	Operator’s and Safety Manual (not shown)

7 1

In case one of the parts listed should not be included in the delivery inventory, please consult your sales agent.

Symbols

You will notice the following symbols on the chain saw and in the Operator’s and Safety Manual:

Read Operator’s and Safety Manual and follow the warningand safety precautions!

Particular care and caution!

Forbidden!

Wear protective helmet, eye and ear protection!

Wear protective gloves!

No smoking!

No open fire!

Stop engine!

Start engine

Combination switch

Start/Stop (I/O), Choke

Safety position

Caution, kickback!

Chain brake

Fuel and oil mixture

Normal / Winter operation

Carburetor adjustment

Chain oil fill/oil pump

Saw chain oil adjustment screw

First aid

Do not touch hot surfaces!

Further

Recycling symbols see page 6.

Safety precautions for chain saw operators

While operating the chain saw please observe the following rules:

a)Contact of the guide bar nose with any object should be avoided.

b)Tip contact may cause the guide bar to move suddenly upward and backward, which may cause serious or fatal injury.

c)Always operate the chain saw with both hands.

WARNING!

Read and follow all safety precautions in the operator’s manual. Failure to follow instructions could result in serious injury. It is recommended to lend the chain saw only to people who are experienced in working with chain saws. Always hand over the Operator’s and Safety Manual.

WARNING!

This chain saw is capable of severe kickback that could result in serious injury to the operator. Do not operate this chain saw unless you have extraordinary cutting needs and experience in and special training for dealing with kickback. Chain saws with significantly reduced kickback potential are available.

WARNING!

Kickback may occur when the nose or tip of the guide bar touches an object, or when the wood closes in and pinches the saw chain in the cut. This contact may abruptly stop the saw chain and in some cases may cause a lightning fast reverse reaction, kicking the guide bar up and back towards the user, or push the guide bar back towards the operator. Kickback may cause you to lose control of the saw.

As a chain saw user, you can take several steps to reduce the risk of a kickback and potential injury.

A.With a basic understanding of kickback, you can reduce or eliminate the element of surprise. It is a sudden surprise that contributes to accidents.

B.Keep a good firm grip on the saw with both hands, your right hand on the rear grip and your left hand on the tubular handle, when the engine is running. Use a firm grip with thumbs andfingersencirclingthechainsawhandles.A firm grip can neutralize kickback and help you maintain control of the saw. Don’t let go!

C.Make sure that the area in which you are cutting is free from obstructions. Do not let the nose of the guide bar contact the log, branch, or any other obstructions which could be hit while you are operating the saw.

D.Do not overreach or cut above shoulder height.

E.Follow manufacturer’s sharpening and main tenance instructions for the saw chain.

F.Only use replacement bars and chains speci fied by the manufacturer or the equivalent.

Additional safety precautions

The following additional safety precautions must be observed by all users of chain saws:

1.Do not operate a chain saw when you are fatigued.

2.Use safety footwear; snug-fitting clothing; protective gloves; and eye, hearing, and head protection devices.

3.Use caution when handling fuel. Move the chain saw at least 10 feet (3 m) from the fueling point before starting the engine.

4.Do not allow other persons to be near the chain saw when starting or cutting with the chain saw. Keep bystanders and animals out of the work area.

5.Do not start cutting until you have a clear work area, secure footing, and a planned retreat path from the falling tree.

6.Keep all parts of your body away from the saw chain when the engine is running.

7.Before you start the engine, make sure that the saw chain is not contacting anything.

8.Carry the chain saw with the engine stopped, the guidebarandsawchaintotherear,andthemuffler away from your body.

9.Do not operate a chain saw that is damaged, is improperly adjusted, or is not completely and securely assembled. Be sure that the saw chain stops moving when the throttle control trigger is released.

10.Shut off the engine before setting it down.

11.Useextremecautionwhencuttingsmallsizebrush and saplings because slender material may catch the saw chain and be whipped toward you or pull you off balance.

12.When cutting a limb that is under tension be alert for springback so that you will not be struck when the tension on the wood fibers is released.

13.Keep the handles dry, clean, and free of oil or fuel mixture.

14.Operate the chain saw only in well-ventilated areas.

15.Do not operate a chain saw in a tree unless you have been specifically trained to do so.

16.All chain saw service, other than the items listed in the operator’s manual maintenance instructions, should be performed by DOLMAR. (For example, if improper tools are used to remove the flywheel or if an improper tool is used to hold the flywheel in order to remove the clutch structural damage to the flywheel could occur and could subsequently cause the flywheel to burst.)

17.When transporting your chain saw, use the chain protection cover.

18.Low kickback bars and low kickback chains are designed to reduce the risk of kickback injury. Ask your DOLMAR dealer about these devices.

General Safety Precautions

The use of any chain saw may be hazardous. At full throttle chain speed can reach 45 mph (20 m/s). It is important that you read; fully understand and observe the following safety precautions and warnings. Read the Operator’s Manual and the safety instructions periodically.

WARNING !

Reactive forces, including kickback, can be dan gerous. Careless or improper use of any chain saw may cause serious or fatal injury.

Have your DOLMAR dealer show you how to operate your chain saw. Observe all applicable local safety regulations, standards and ordinances.

WARNING!

Minors should never be allowed to use a chain saw.

Bystanders, especially children and animals should not be allowed in the area where a chain saw is in use (fig. 1).

Never let the saw run unattended.

Store it in a locked place away from children. Fill the fuel tank to 7/8 th full (see storing the saw).

Do not lend your chain saw without this Operator’s and Safety Manual. Be sure that anyone using your saw understands the information given.

Proper use of a chain saw involves 1. the operator

2. the saw

3. the use of the saw.

Discription of symbols used on chain saws:

		CSA Standards	Z62.1-03
C	US	Class 1A	Z62.3-04
		ANSI Standard	B175.1-2000
		SAE Standard	SAE J335

max. CKA 45O		Maximum Computed Kickback Angle
		(CKA)* without using the chain brake when
		using the recommended bar and chain
		combinations (In this example the CKA is 45°).
max. CKA 40O		MaximumComputed Kickback Angle
		(CKA)* with using the chain brake when
		using the recommended bar and chain
		combinations (In this example the CKA is 40°).

			Contact of the guide bar tip with
			any object should be avoided!
			Tip contact may cause the guide
			bar to move suddenly upward
			and backward, which may cause
			serious injury!
			Always use two hands when
			operating the chain saw!
			Reduced Kickback Bar and
			Chain combination that has been
	XXX.YYY.ZZZ		evaluated with the power head
			to achieve kickback protection
XXX.YYY.ZZZ			(according	to ANSI and CSA
			standards).

* The Computed Kickback Angle is a calculated value from energies measured on a test bench.It is not the angle of the guide bar moved upward in case of a KICKBACK.

The operator

Physical Condition

You must be in good physical condition and mental health and not under the influence of any substance (drugs, alcohol), which might impair vision, dexterity or judgment.

WARNING !

Prolongeduseofchainsawsexposingtheoperator tovibrationsmayproduceWhitefingerdisease(Ray naud’s phenomenon). This phenomenon reduces the hand’s ability to feel and regulate temperature, produces numbness and burning sensations and may cause nerve and circulation damage and tissue necrosis.

All DOLMAR saws are therefore provided with an antivibration system which is essential for those using chain saws on a regular or sustained basis. Antivibration systems do not guarantee that you willnotsustainWhitefingerdisesase,however,they reduce this danger considerably. Nevertheless, continual and regular users should observe their hands and fingers and in case of any abnormal symptoms, seek medical advice immediately.

Proper clothing

Clothing must be sturdy and snug-fitting, but allow complete freedom of movement. Avoid loose-fitting jackets,scarfs,neckties,jewelry,flaredorcuffedpants, or anything that could become entangled with the saw or brush. Wear overalls or jeans with a reinforced cutting resistant insert (fig. 3).

Protect your hands with gloves when handling saw and saw chain. Heavy-duty, nonslip gloves improve your grip and protect your hands.

Good footing is most important in chain saw work. Wear sturdy boots with nonslip soles. Steel-toed safety boots are recommended.

Proper eye protection is a must. Non-fogging, vented goggles and a face screen is recommended. Their use reduces the risk of eye and facial injury.

Wear an approved safety hard hat to protect your head. Chain saw noise may damage your hearing. Always wear noise protection equipment (ear plugs or ear muffs) to protect your hearing.

Continual and regular users should have their hearing checked regularly.

Wear protective helmet, eye and ear protection!

The saw

Parts of the chain saw: illustrations and description of parts see page 17.

WARNING !

Never modify a chain saw in any way. Only attachments supplied by DOLMAR or expressly approved by DOLMAR for use with the specific saw are authorized.

WARNING !

Bow guide bars substantially increase the potential for kickback and severe or fatal injury due to the greater kickback zone of the bow design. Bow guide bars are not recommended for use on DOLMAR chain saws nor are they approved by the ANSI B

175.1-2000 chain saw safety standard.

The use of the saw

Transporting the chain saw

WARNING!

Always stop the engine before putting a chain saw down or carrying it. Carrying a chain saw with the enginerunningisextremelydangerous.Accidental acceleration of the engine can cause the chain to rotate.

Avoid touching the hot muffler.

By hand: When carrying your saw by hand, the engine must be stopped and the saw must be in the proper position.

The chain protection cover should be over the chain and the guide bar must point backwards. When carrying your saw the bar should be behind you (fig. 4).

By vehicle: When transporting in a vehicle, keep chainandbarcoveredwiththechainguard.Properly secure your saw to prevent turnover, fuel spillage and damage to the saw. Make sure the saw in not exposed to heat or sparks.

Chain saw operating instructions

For assembly follow the procedure in the appropriate section "Mounting Guide Bar and Chain" of this manual. DOLMARchain,guidebarandsprocketmustmatcheach other (see the appropriate section in this manual).

WARNING!

Proper tension of the chain is extremely important. In order to avoid false setting the tensioning procedure must be followed as described in this manual. Always make sure the hexagonal nut(s) for the sprocket guard is (are) tightened securely after tensioning the chain. Check chain tension once more after having tightened the nuts and thereafter at regular intervals (always before starting to work). If the chain becomes loose while cutting, shut off the engine and then tighten. Never try to tighten the chain while the engine is running!

Fueling

Your DOLMAR saw uses on oil-gasoline mixture for fuel (see chapter "Fuel" of this manual).

WARNING!

Gasoline is an extremely flammable fuel. Use extreme caution when handling gasoline or fuel mix. Do not smoke or bring any sparks or flame near the fuel (fig. 5).

Fueling instructions

Fuel your chain saw in well ventilated areas or outdoors. Always shut off the engine and allow it to cool before refueling. Select bare ground for fueling and move the chain saw at least 10 feet (3 m) from fueling spot before starting the engine (fig. 5a).

10	feet
	5a

Wipe off any spilled fuel before starting your saw and check for leakage.

Check for fuel leakage while refueling and during operation. If fuel or oil leakage is found, do not start or run the engine until leak is fixed and spilled fuel has been wiped away. Clothing with fuel on it has to be changed immediately (this is a danger to your life!).

Avoid skin contact with fuel. Never loosen or remove the cap of the fuel tank while the engine is running.

Starting

Do not drop start. This method is very dangerous because you may lose control of the saw (fig. 6).

Place the chain saw on firm ground or other solid surface in an open area. Maintain a good balance and secure footing. Place your right foot through the rear handle opening and firmly grasp the front handle with your left hand (fig. 6a).

Be absolutely sure that guide bar and chain are clear of you or all other obstructions and objects, including the ground, because when the engine starts in semithrottle position, engine speed will be fast enough for the clutch to engage the sprocket and turn the chain which may cause a kickback.

Never attempt to start the saw when the guide bar is in a cut or kerf.

When you pull the starter grip, don’t wrap the starter rope around your hands. Do not allow the grip to snap back, but guide the starter rope slowly back to permit the rope to rewind properly. Failure to follow this procedure may result in injury to hand or fingers and may damage the starter mechanism.

Important adjustments

WARNING!

At correct idle speed, chain should not turn. For directions to adjust idle speed, see the appropriate section of this operator’s manual.

Do not use a saw with incorrect idle speed adjustment. Adjust the idle speed yourself according to the appropriate section of this manual.

Have your DOLMAR dealer check your saw and make proper adjustments or repairs.

Check the saw chain tension frequently, especially just after installing a new chain. New chains may stretch more during their initial use. A properly adjusted saw chain can be pulled freely around the guide bar by hand without sagging. Always stop the engine and wear gloves when checking or ad justing the chain tension.

Working conditions

Operate your chain saw only outdoors. Operate the saw under good visibility and daylight conditions only.

WARNING!

Take extreme care in wet and freezing weather

(rain, snow, ice). Put off the work when the weather is windy, stormy or rainfall is heavy. Clear the area where you are working.

WARNING!

Avoid stumbling on obstacles such as stumps, roots or rocks and watch out for holes or ditches.

Be extremely cautious when working on slopes or uneven ground. There is increased danger of slipping on freshly debarked logs.

Cutting instructions

Always hold the saw firmly with both hands when the engine is running. Place your left hand on the tubular handle and your right hand on grip and throttle lever. Left-handers should follow these instructions too.

Wrap your fingers tightly around the handles, keeping the handles cradled between your thumb and forefinger (fig. 7). With your hands in this position, you can best oppose and absorb the push, pull and kickback forces of your saw without having it slip out of your grip (see section of reactive forces). Make sure your chain saw handle and grip are in good condition and free of moisture, pitch, oil or grease.

Always start a cut with the chain running at full speed and the spike bar in contact with the wood.

WARNING!

Never use the saw with one hand. You cannot control reactive forces (see pages 10 to 12) and may lose control of the saw.

WARNING!

Do not operate your chain saw in semi-throttle position. Cutting in this position does not permit the operator proper control of the saw or chain speed.

WARNING!

Never come too close to a rotating chain with your hands or body.

WARNING!

Do not cut any material other than wood or wooden objects.

Use your chain saw for cutting only. It is not designed for prying or shoveling away limbs, roots or other objects.

When sawing, make sure that the saw chain does not touch any foreign materials such as rocks, nails and the like (fig. 8). Such objects may be flung off, damage the saw chain or cause the saw to kickback.

In order to keep control of your saw, always maintain a firm foothold. Never work on a ladder, in a tree or on any other insecure support. Never use the saw above shoulder height (fig. 9).

Position the chain saw in such a way that your body is clear of the cutting attachment whenever the engine is running (fig. 10).

Don’t put pressure on the saw when reaching the end of a cut. The pressure may cause the bar and rotating chain to pop out of the cut or kerf, go out of control and strike the operator or some other object. If the rotating chain strikes some other object a reactive force (see pages 11 to 13 ) may cause the chain to strike the operator.

Reactive forces during the cut, including kickback

WARNING!

Reactive forces, that may occur during any cut are kickback, pushback and pull-in. Reactive forces can be dangerous! In any chain saw, the powerful force used to cut wood can be reversed (and work against the operator).

If the rotating chain is suddenly stopped by contact with any solid object like a log or branch or is pinched, the reactive forces instantly occur. These reactive forces may result in loss of control which may, in turn, cause serious or fatal injury. An understanding of the causes of these reactive forces may help you avoid loss of control.

The most common reactive forces are - kickback,

- pushback, - pull-in.

Kickback:

Kickback occurs when the upper quadrant of the bar nose contacts a solid object in the wood or is pinched

(fig. 11). The reaction of the cutting force of the chain causes a rotational force of the chain saw in the direc tion opposite to the chain movement, mainly in the plane of the bar. This may fling the bar in an uncontrolled arc towards the operator.

This reaction can occur in a fraction of a second and under some circumstances, cause the guide bar and chain to strike the operator with enough force to cause severe or fatal injury. It may also occur during limbing. It also occurs when the nose of the guide bar is pinched unexpectedly, unintentionally contacts solid material in the wood (fig.12) or is incorrectly used to begin a plunge or boring cut.

The greater the force of the kickback reaction, the more difficult it becomes for the operator to control the saw.

Many factors influence the occurence and force of the kickback reaction.The type of bar and saw chain you use is a factor in the force of the kickback reaction.

The speed of contact at which the cutter contacts the object.

Kickback force increase with the rate of impact.

The contact angle between the nose of the bar and the foreign object (fig. 11).

Kickback is most pronounced in the upper quadrant of the bar nose.

DOLMAR chain types are designed to reduce kickback forces.

The depth gauges:

Improper lowering of the depth gauges also increases the risk of a kickback.

Saw chain cutter sharpness:

WARNING!

A dull improperly sharpened chain may increase the risk of kickback. Always cut with a properly sharpened chain.

Devices for reducing the risk of kickback injury

DOLMAR have developed a special chain brake to reduce the risk of kickbacks.

This chain brake increases the safety factor on the job, e.g. when the saw suddenly bucks upwards the chain stops rotating within a fraction of a second. A deflection guard on the disengaging lever of the chain brake and a scoop rear handle ensure that the operator’s hands are fully protected at all times.

Kickback tendency increases as the radius or size of the guide bar nose increases. DOLMAR have developed guide bars with small nose radius, to reduce the kickback tendency.

WARNING!

No chain brake prevents kickback.

These brakes are designed only to stop the chain, if activated.

To ensure a proper operation of the chain brake, it must be properly maintained. Furthermore, there must be a sufficient distance between the operator and the bar to ensure that the chain brake has sufficienttimetoactivateandstopthechainbefore potential contact with the operator.

To avoid kickback

The best protection from personal-injury that may result from kickback is to avoid kickback situations:

1.Hold the chain saw firmly with both hands and maintain a secure grip.

2.Be aware of the location of the guide bar nose at all times.

3.Never bring the nose of the guide bar in contact with any object. Do not cut limbs with the nose of the guide bar. Be especially careful with small, tough limbs, small size brush and saplings which may easily catch the chain.

4.Don’t overreach.

5.Don’t cut above shoulder height.

6.Begin cutting and continue at full throttle.

7.Cut only one log at a time.

8.Use extreme caution when re-entering a previous cut.

9.Do not attempt plunge cuts (see page 14) if you are not experienced with these cutting techniques.

10.Be alert for shifting of the log or other forces that may cause the cut to close and pinch the chain.

11.Maintain saw chain properly. Cut with a correctly sharpened, properly tensioned chain at all times.

12.Stand to the side of the cutting path of the chain saw.

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).

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 14 and 16), because the chain can pinch.

Pull-in:

Pull-in occurs when the chain on the bottom of the bar is suddenly stopped. The chain on the bottom of the bar stops when it is pinched, caught or encounters a foreign object in the wood (see fig. 15). The reaction of the chain pulls the saw forward, causing the operator to lose control.

Pull-in frequently occurs when the spike bar of the saw is not held securely against the tree or limb and when the chain is not rotating at full speed before it contacts the wood.

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.Pull-in may also be prevented by using plastic wedges to open the kerf or cut.

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 up-hill side.

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.

45°

2 1 2

45°

= cutting down area

When felling, maintain a distance of at least 2 1/2 tree lengths from the nearest person (see fig. 17).

Note:

The noise of your engine may drown any warning call.

Felling instructions:

First clear the tree base and work area from interfering limbs and brush and clean its lower portion an axe (see fig. 18).

45°

Then, establish a path of escape and remove all obstacles. This path should be opposite to the planned direction of the fall of the tree and at a 45° angle (fig.

19). An alternate path must also be selected. Place all tools and equipment a safe distance away from the tree, but not on the escape path.

First cut

Second cut

If the tree has large buttress roots, cut into the largest buttressesverticallyfirst(horizontallynext)andremove (fig. 20).

Direction of fall

Felling cut	/ 0
	/ 0	Hinge
		Hinge
/2" (4cm)		Felling notch
		/5
			22
	Felling notch	Hinge	23
			23

Then, determine the placement of the felling notch

(fig. 21). The felling notch when properly placed determines the direction in which the tree will fall. It is made perpendicular to the line of fall and should be as close to the ground as possible. Cut the felling notch to a depth of about one-fifth to one-fourth of the trunk diameter (fig. 22). It should be in no case higher than it is deep. Make the felling notch very carefully.

Begin the felling cut slighty higher than the felling notch and on the opposite side of the tree (fig. 22). Then cut horizontally through towards the felling notch. Apply the chain saw with its spikes directly behind the uncut portion of wood and cut toward the notch (fig. 23). Leave approximately 1/10 of the tree diameter uncut! This is the hinge (fig. 23). Do not cut through the hinge because you could lose control of the direction of the fall. Drive wedges into the felling cut where necessary to control the direction of the fall. Wedges should be of wood, light alloy or plastic - never of steel, which can cause kickback and damage to the chain.

Always keep to the side of the falling tree. When the tree starts to fall, shut off the engine, withdraw the bar and walk away on the pre-planned escape path. Watch out for falling limbs.

WARNING!

Beextremelycarefulwithpartiallyfallentreeswhich are poorly supported.

When the tree hangs or for some other reason does not fall completely, set the saw aside and pull the tree down with a cable winch, block and tackle or tractor. If you try to cut it down with your saw, you may be injured.

Plunge-Cut Method

Timber having a diameter more than twice the length of the guide bar reauires the use of the plunge-cut method before making the felling cut.

First, cut a large, wide notch. Make a plunge cut in the center of the notch.

The plunge cut is made with the guide bar nose. Begin the plunge cut by applying the lower portion of the guide bar nose to the tree at an angle (fig. 25). Cut until depth of the kerf is about the same as the width of the guide bar (fig. 26). Next, align the saw in the direction

in which the recess is to be cut. With the saw at full throttle, insert the guide bar in the trunk (fig. 27).

Enlarge the plunge cut as shown in illustration (fig. 28)

Sectioning Method

WARNING!

Felling a tree that has a diameter greater than the length of the guide bar requires use of either the sectioning or plunge-cut method. These methods are extremely dangerous because they involve the use of the nose of the guide bar and can result in kickback. Only properly trained professionals should attempt these techniques.

2	3
	24

For the sectioning method (fig. 24) make the first cut with the guide bar fanning in toward the hinge. Then, using the bumper spike as a pivot, reposition the saw for the next cut.Avoid repositioning the saw more than necessary. When repositioning for the next cut, keep the guide bar fully engaged in the kerf to keep the felling cut straight. If the saw begins to pinch, insert a wedge to open the cut. On the last cut, do not cut the hinge.

WARNING!

There is an extreme danger of kickback at this point. Extra caution must be taken to maintain control of the saw. To make the felling cut, follow the sectioning method described previously (fig. 29). If you are inexperienced with a chain saw plunge-cutting should not be attempted. Seek the help of a professional.

Limbing

Limbing is removing the branches from a fallen tree.

WARNING!

There is an extreme danger of kickback during the limbing operation. Do not work with the nose of the bar. Be extremely cautious and avoid contacting the log or other limbs with the nose of the guide bar. Do not stand on a log while limbing it - you may slip or the log may roll.

Start limbing by leaving the lower limbs to support the log off the ground (fig. 30). Always cut from the top of the limb. Do not underbuck freely hanging limbs. A pinch may result or the limb may fall, causing loss of control. If a pinch occurs, stop the engine and remove the saw, by lifting the limb.

WARNING!

Be extremely cautious when cutting limbs under tension. The limbs could spring back toward the operator and cause loss of control of the saw or injury to the operator.

Bucking

Bucking is cutting a log into sections.

WARNING!

1.When bucking, do not stand on the log. Make sure the log will not roll down-hill. If on a slope, stand on the up-hill side of the log (see fig. 31).

Watch out for rolling logs.

WARNING!

2. Cut only one log at a time.

WARNING!

3.Shattered wood should be cut very carefully.

Sharp slivers of wood may be caught and flung in the direction of the operator of the saw.

WARNING!

4.When cutting small logs, use a sawhorse (fig.

32). Never permit another person to hold the log. Never hold the log with your leg or foot.

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