Stihl 4282 Series, BR 550, BR 600, BR 500 Technical Information
STIH)
Technical Information
New STIHL BR 500, BR 550 and BR 600 backpack blowers – Series 4282
Contents
1. Technical description
2. Specifications
3. Accessories
4. Service accessories and special tools
5. Service notes
08.2005
TI_08_2005_11_01_02.fm
englisch / English
Page 2 Technical Information 08.2005
The new STIHL BR 500, BR 550 and BR 600
backpack blowers are three ideal models for
demanding, professional users.
The BR 500 is especially low-noise yet highly
powerful for use in noise-sensitive areas.
The BR 550 has an attractive price with far aboveaverage blowing strength.
The BR 600 is particularly powerful - one of the
strongest blowers in the world.
The STIHL 4-MIX engine of the new blowers sets
benchmarks in blowing strength, economy and
environmental friendliness.
Comfort is increased with the simplified starting
procedure. This is realised with the newly designed
control handle and central control section that holds
all operating elements required for starting.
Another innovation is the electrostatic arrester in the
blowing system that protects the user from
electrostatic shock.
The devices are equipped with an adjustable
carrying system with breathing padding for superior
wearing comfort.
The holder for the blowing system makes the
devices easier to transport and saves space in
storage.
1. Technical description
1.1 Blowing system with electrostatic arrester
The extremely high flow of air from the new blowers
generates friction in the blower tubes. The friction
can build up an electrostatic charge.
The arrester in the blower tube creates a conductive
link to the engine block to prevent the build up of
electrostatic charges that can lead to sparkover.
. Before starting the blower, check to see if it is
intact and seated correctly. If the arrester is
damaged, replace it (see 5.6).
. Never operate the machine without an arrester.
TI_08_2005_11_01_02.fm
Technical Information 08.2005 Page 3
1.2 Control handle
For simplified starting, the choke does not have to
be set on the control handle.
Since the setting lever does not lock at
"Engine Stop" (0), the ignition system is
continuously ready to operate, and the blower can
be started at any time.
1
2
. Setting lever (1)
. Throttle trigger (2)
Engine stop (0)
. The ignition system is sent a stop pulse to shut
off the blower.
. The setting lever does not lock but rather
springs back – the ignition system is
automatically ready to operate.
1.3 Simplified starting
All operating elements for starting are on a central
control area. Set the starting throttle position with
the choke knob. The choke knob automatically
springs back into operating position after the throttle
trigger is actuated.
. Press the fuel pump bulb at least five times.
. Setting the choke knob:
When the engine is cold l
When the engine is hot n
. Pull the cord until the engine starts; at the latest,
set the choke knob to starting throttle position
n after the third time the cord is pulled.
. Set the choke knob to the starting throttle
position n
. Continue cranking until the engine runs.
Operating position (#)
. The engine is running or can start – the throttle
trigger can be smoothly actuated.
Set locked position (C)
. The throttle trigger can be locked at three levels:
1/3 gas, 2/3 gas and full throttle.
. To release the locked position, set the setting
lever to #.
To switch to idle:
. Pull the throttle trigger - the choke knob
automatically jumps to operating position #
or
. Set the choke knob manually to #
TI_08_2005_11_01_02.fm
Page 4 Technical Information 08.2005
1.4 Blower holder
For storage and transport:
. Affix the Velcro tape to the blower tube, pull the
tab through the cinch.
1.5 STIHL 4-MIX engine
The 4-MIX engine works with mixed lubrication.
Unlike a conventional four-stroke engine, the 4-MIX
engine does not have any supply of oil in the
crankcase. The engine is lubricated entirely with a
mixture of petrol and engine oil.
This design yields the following advantages:
. Same fuel
. Lower fuel consumption
. Can be operated in all positions
. Fewer emissions
. Good acceleration
. Compact size – attractive design
. Advantageous power-to-weight ratio
. Easy maintenance – easy to service
. Pleasanter sound – lower noise level
. Fewer vibrations
. Lower starting force
. Affix the blower tube to the handle opening of
the back plate.
TI_08_2005_11_01_02.fm
Technical Information 08.2005 Page 5
1.5.1 Engine design
Single-cylinder engine with overhead valves.
Cylinder head, cylinder and upper half of crankcase
have been combined into a single unit.
The crankcase is horizontally split along the
crankshaft.
1.5.2 Engine control
7
1
2
6
5
4
3
. Overhead valves (OHV), one exhaust valve (1)
and one inlet valve (2)
. Valve control via crankshaft gear (3),
cam disk (4), lever (5), pushrod (6) and
rocker arm (7)
254TI011 KN
. Crossflow scavenging
(= inlet and exhaust on opposite sides)
TI_08_2005_11_01_02.fm
Page 6 Technical Information 08.2005
1.5.3 Engine lubrication
The engine is lubricated in two phases during each
revolution of the crankshaft.
Phase 1
The piston rises to the top dead centre.
Phase 2
The piston descends to the bottom dead centre.
The increase in volume in the crankcase produces
a vacuum. From the intake duct (1), the air-fuel-oil
mixture is drawn through the bypass port (2), valve
train (3) and timing gear (4) into the crankcase (5).
The oil contained in this mixture lubricates the
crankgear, timing gear, valve train and cylinder wall.
Excess pressure builds up in the crankcase due to
the decrease in volume.
The mixture of air, fuel and oil in the crankcase is
returned to the intake duct via the timing gear, valve
train and bypass bore. This rewets the lubrication
points.
TI_08_2005_11_01_02.fm
Technical Information 08.2005 Page 7
1.6 Decompression system
The automatic decompression system reduces the
compression upon starting and hence the required
pull on the starter rope.
Cam disk at low speed (starting):
. Decompression cam (1) projects and actuates
the lever (2)
. This lengthens the valve opening time, which
reduces the compression
Cam disk when the engine has started:
1.7 Carburetor
. All-position diaphragm carburetor with
independent idle
. The range of the high-speed adjusting screw (H)
and the low-speed adjusting screw (L) is limited
by limiter caps (approx. 3/4 turn). This limitation
ensures greater operating safety and
maintenance of future exhaust emission levels
. Accelerator pump for faster and spontaneous
acceleration (see 5.3).
. Choke knob with integrated starting throttle
position
1.8 Ignition system
. Microprocessor-controlled with ignition timing
adjustment
. Low power-up threshold
1.9 Air filter
. Large-area paper air filter for long filter service
life
. Easily accessible
. The centrifugal mechanism retracts the
decompression cam (1) – this cancels the effect
of the decompression cam
1.10 Muffler
. Two-chamber muffler with spark arresting
screen, depending on the market concerned.
1.11 Flywheel
. Weight-optimised geometry
TI_08_2005_11_01_02.fm
Loading...