Stihl Sr 420 Instruction Manual Download Page 7

Watch out for obstacles: Be careful of refuse,

tree stumps, roots and ditches which could

cause you to trip or stumble
Be particularly alert and cautious when wearing

hearing protection because your ability to hear

warnings (shouts, alarms, etc.) is restricted.
Take breaks when you start getting tired or feel‐

ing fatigue – risk of accidents!
Work calmly and carefully – in daylight conditions

and only when visibility is good. Proceed with

caution, do not put others in danger.
Do not work on a ladder or in unstable locations.
When working in open ground and gardens take

special care to avoid harming small animals.
To reduce the risk of electrocution, never operate

this power tool in the vicinity of live wires or

power cables.
Always clean the spray container and hose sys‐

tem before changing to a different plant protec‐

tion product.

As soon as the engine is running, the

power machine generates toxic

exhaust gas.As soon as the engine is

running, the power machine gener‐

ates toxic exhaust gas. These gases

may be odorless and invisible and

may contain unburned hydrocarbons

and benzene. Never work with the

machine in closed or poorly ventilated

rooms.

To reduce the risk of serious or fatal injury from

breathing toxic fumes, ensure proper ventilation

when working in trenches, hollows or other con‐

fined locations.
Stop work immediately if you start suffering from

nausea, headaches, impaired vision (e.g. your

field of vision gets smaller), impaired hearing,

dizziness, or impaired concentration – these

symptoms may possibly be the result of too-high

exhaust gas concentration – Risk of accidents!
Operate your power tool so that it produces a

minimum of noise and emissions – do not run the

engine unnecessarily, accelerate the engine only

when working.
To reduce the risk of fire, do not smoke while

operating or standing near your power tool. Com‐

bustible fuel vapor may escape from the fuel sys‐

tem.
If your power tool is subjected to unusually high

loads for which it was not designed (e.g. heavy

impact or a fall), always check that it is in good

condition before continuing work – see also

"Before Starting". Check the fuel system for

leaks and make sure the safety devices are

working properly. Do not continue operating your

power tool if it is damaged. In case of doubt, con‐

tact a dealer.

2.13

After finishing work

Close the valve lever.
Always shut off the engine before taking the

power tool off your back.
After finishing work, put the power tool down on

a level, non-flammable surface. Do not place the

machine near easily flammable materials (e.g.

wood chips, bark, dry grass, fuel) – risk of fire!
Check all parts of the power tool for leaks.
After finishing work, thoroughly clean the power

tool and wash your hands, face and, if neces‐

sary, your clothes.
Keep other people and animals away from the

areas that have been sprayed and do not walk

on them until the plant protection chemical has

dried.

2.14

Vibrations

Prolonged use of the power tool may result in

vibration-induced circulation problems in the

hands (whitefinger disease).
No general recommendation can be given for the

length of usage because it depends on several

factors.
The period of usage is prolonged by:

Hand protection (wearing warm gloves)

Work breaks

The period of usage is shortened by:

Any personal tendency to suffer from poor cir‐

culation (symptoms: frequently cold fingers,

tingling sensations).

Low outside temperatures.

The force with which the handles are held (a

tight grip restricts circulation).

Continual and regular users should monitor

closely the condition of their hands and fingers. If

any of the above symptoms appear (e.g. tingling

sensation in fingers), seek medical advice.

2.15

Maintenance and Repairs

Service the machine regularly. Do not attempt

any maintenance or repair work not described in

2 Safety Precautions and Working Techniques

English

0458-372-0121-C

7

Summary of Contents for Sr 420

Page 1: ...SR 420 Instruction Manual 2 25...

Page 2: ...e machine or its individual components 1 3 Engineering improvements STIHL s philosophy is to continually improve all of its products For this reason we may modify the design engineering and appearance...

Page 3: ...use of the increased risk of accidents and damage to the power tool The product must not be modified in any way this may also lead to accidents or damage to the unit 2 3 Accessories and replacement pa...

Page 4: ...fumes or explo sive solutions Do not mix different plant protection products unless such a mixture is approved by the man ufacturer 2 5 2 Filling the Solution Container Stand the power tool securely...

Page 5: ...l quantities of fuel 2 8 Before starting Check that your power tool is properly assem bled and in good condition especially if it has been subjected to unusually high loads for which it was not design...

Page 6: ...charges Do not operate your machine on a non conduc tive surface e g plastic asphalt Never operate your machine with a missing or damaged discharge system Follow the mounting instructions supplied wi...

Page 7: ...r your power tool Com bustible fuel vapor may escape from the fuel sys tem If your power tool is subjected to unusually high loads for which it was not designed e g heavy impact or a fall always check...

Page 8: ...service or store your machine near open flames Check the fuel filler cap for leaks at regular inter vals Use only a spark plug of the type approved by STIHL and make sure it is in good condition see...

Page 9: ...4 to secure hose 1 and hose 3 to the stubs on the stop cock Close the stop cock move lever to vertical position Fill up with water and check all hose connec tions for leaks 3 4 Adjusting the Control...

Page 10: ...n lead to severe engine damage The engine seals fuel lines and fuel tank may be damaged if low quality gasoline or engine oil is used 5 2 1 Gasoline Use only high quality gasoline with an octane rat i...

Page 11: ...ilt up in the canister open it carefully The fuel tank and the canister in which fuel mixture is stored should be cleaned thoroughly from time to time Residual fuel and the liquid used for cleaning mu...

Page 12: ...r if the engine is not shut off in the idle position The throttle cable reconnects itself automatically when the setting lever is moved to the idle posi tion 8 Starting Stopping the Engine 8 1 Startin...

Page 13: ...ainst the base plate to prevent it slipping Hold the starter grip with your right hand Pull the starter grip slowly until you feel it engage and then give it a brisk strong pull NOTICE Do not pull out...

Page 14: ...ops simply multiply the length of the field by its width The surface area of high growing plants is calcu lated approximately by measuring the length of the rows and the average height of the foliage...

Page 15: ...ers by the time in minutes gives you the walking speed in meters per minute m min Example The distance covered in one minute is 10 meters Walking speed 10 m 10 m min 1 min 9 5 Determining discharge ra...

Page 16: ...666 1 747 1 700 2 2 928 2 896 2 864 ULV metering knob Discharge rate in l min Blower tube angle Knob set ting 30 0 30 0 5 0 142 0 132 0 128 0 65 0 216 0 212 0 203 0 8 0 352 0 403 0 377 10 5 Checking...

Page 17: ...06 KN Spray solution is finely atomized short broad and dense spray mist 12 2 Deflector Screen 372BA007 KN Diverts spray jet at an angle for under leaf treatment of low growing crops 12 3 Dual Deflect...

Page 18: ...lace if nec essary Check the spark arresting screen not in all models country specific in the muffler and clean or replace if necessary H L 373BA043 KN Carefully turn both adjusting screws counter clo...

Page 19: ...esting Screen in Muffler WARNING To reduce the risk of fire caused by hot particles escaping from the machine never operate the machine without a spark arresting screen or with the spark arresting scr...

Page 20: ...16 2 Checking the Spark Plug 000BA039 KN A Clean dirty spark plug Check electrode gap A and readjust if neces sary see Specifications Rectify the problems which have caused foul ing of the spark plug...

Page 21: ...ifficult cutting conditions extensive dust etc Before starting work At the end of work and or daily Whenever tank is refilled Weekly Monthly Annually If faulty If damaged As required Complete machine...

Page 22: ...sports or competitive events Consequential damage caused by continuing to use the product with defective components 19 1 Maintenance Work All the operations described in the Maintenance Chart must be...

Page 23: ...3 5 bhp Idle speed 3 100 rpm Engine blower speed dur ing operation 7 500 rpm 22 2 Ignition System Electronic magneto ignition Spark plug resistor type Bosch WSR 6 F NGK BPMR 7 A Electrode gap 0 5 mm 2...

Page 24: ...ribed in this User Manual The oper ating license shall be void if the engine is modi fied in any way 23 Maintenance and Repairs Users of this machine may only carry out the maintenance and service wor...

Page 25: ...ured in com pliance with the following standards in the ver sions valid on the date of production ISO 12100 EN 55012 EN 61000 6 1 EN ISO 28139 Technical documents deposited at ANDREAS STIHL AG Co KG P...

Page 26: ...English 25 EC Declaration of Conformity 26 0458 372 0121 C...

Page 27: ...25 EC Declaration of Conformity English 0458 372 0121 C 27...

Page 28: ...www stihl com 04583720121C 04583720121C 0458 372 0121 C 0458 372 0121 C...

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