Technical Information · issue 3 of 2010

New STIHL HT 56 C-E Pole Pruner

IssueTI 3/2010

Full text

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STIH)

Technical Information 03.2010

New STIHL HT 56 C-E Pole Pruner – Series 4139

Contents
1. Technical Description
2. Specifications
3. Special Accessory
4. Servicing Accessories
5. Note on Assembly
6. Spare Parts
7. Repairs

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)m~ge 2 Technical Information 03.2010

1. Technical Description 1.2 Choke lever

The new HT 56 C-E is the latest addition to the
STIHL line of pole pruners. It can prune branches up
to a height of 13 feet.
The cutting attachment of the HT 56 C-E is driven
by the powerful and fuel-efficient 4144 series
engine.
The unit features a split drive tube (boom) which
1
provides plenty of reach and helps with
transportation and storage.

546TI001 KN
The overall concept has been designed for
reliability, ruggedness and low maintenance.
The ergonomically designed controls, comfortable To start the engine, the choke lever (1) has to be
full-length handle hose, favorable power-to-weight pressed in and turned to g (cold start) or <
ratio and easy starting system ensure simple (warm start). After the engine starts, the choke lever
handling and less fatigue during operation. returns automatically to F (normal run position) as
soon as the interlock lever and throttle trigger are
1.1 Function of stop switch and the ignition operated. It is not necessary for the user to move
the choke lever to F (normal run position).

1.3 Starter mechanism with STIHL
1 Easy2Start™
The STIHL Easy2Start™ starter mechanism is
designed for a low cranking effort and a low, uniform
cranking speed. This ensures jerk-free starts and
requires less pulling effort.
546TI000 KN

The stop switch (1) is normally in the Run position:
The ignition is switched on – the engine is ready to
start. The ignition is switched off when the stop
switch is moved to the 0 position. The ignition is
switched on again automatically after the engine
stops.

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Technical Information 03.2010 Page 3

1.4 Engine with Stratified Scavenging The fuel-air mixture (1) and pure air (2) flow via the
carburetor into different ports. There are control
1.4.1 Method of operation recesses (3) at both sides of the piston skirt. The
piston's control recesses open and close the
connection between the pure air port and the
transfer port (4). No additional components are
required to control the flow of pure air.
An air buffer (fuel-free air) separates the fuel-air
mixture and exhaust gas. The air buffer flows into
the cylinder ahead of the fuel-air mixture. When the
exhaust/transfer stroke starts, fuel-free air flows
initially from the transfer ports into the combustion
chamber and flushes the exhaust gas into the
exhaust port. The air buffer prevents the
3 subsequent charge of fuel-air mixture from escaping
through the exhaust port. This helps minimize
2 4 harmful emissions by reducing scavenging losses
containing fuel and also reduces fuel consumption.
1
546TI002 KN

1.4.2 Carburetor

2 3

2 6 3 5

1
546TI003 KN

a) Full load, b) Idle c) Cold start d) Warm start
part load

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Full load and part load Cold start
The air filter (1) divides the intake air into two The choke shutter is closed for the cold start. The
streams. The choke shutter (2) and throttle throttle shutter is opened slightly. The required
shutter (3) are open. The incoming air flows through volume of air for an optimum starting mixture is
the carburetor (4) above and below the choke and drawn through the holes in the choke shutter – the
throttle shutters. Fuel is drawn into the upper part of required volume of fuel is drawn from the idle and
the carburetor and flows through the venturi – main jets.
a fuel-air mixture is created. Warm start
In the spacer flange (5) the fuel-air mixture is
diverted into the crankcase and the pure air into the The choke and throttle shutters are opened to a
transfer ports. defined angle for a warm start so that the engine
receives an ideal fuel-air mixture for the start.
In the carburetor there is a partition (6) between the
choke and throttle shutters which separates the fuel-
1.5 Cutting attachment
air mixture and pure air paths at full throttle.
The 1/4" STIHL Rapid™ Micro™ Special (13 RMS)
Idle is a low vibration chain with smooth cutting behavior,
The choke shutter is open. The throttle shutter is excellent start-of-cut and control characteristics.
closed to a point that leaves only a narrow gap Furthermore, used in combination with the STIHL
between it and the carburetor body. Rich fuel-air Duromatic C guide bar, it has a high plunge-cutting
mixture is drawn in from the idle bore next to this capacity, ensures easier plunge cuts and reduces
gap. Air is drawn in through the two small holes in the load on the bar nose.
the throttle shutter and the gap – which dilutes the The tapered bar and the very small nose radius
rich fuel-air mixture to produce an optimum fuel-air allow convenient cutting between closely spaced
mixture for idle. branches.

2. Specifications

2.1 Engine

Single cylinder two-stroke engine
Displacement: 1.66 cu. in. (27.2 cc)
Bore: 1.34 in. (34 mm)
Stroke: 1.18 in. (30 mm)
Engine power to ISO 8893: 1.1 bhp (0.8 kW)
Torque: 0.99 lb.ft. (1.35 Nm)
Idle speed: 2,800 rpm
Cut-off speed
(rated): 10,000 rpm
Rewind starter: Two pawl system
– Starter rope: 0.11 in. diameter, 39.8 in. long
(2.7 mm diameter, 1010 mm long)
– Rewind spring reserve: 1.25 – 2.25 turns

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Technical Information 03.2010 Page 5

2.2 Fuel System
Carburetor: All position diaphragm carburetor with integral fuel pump.

Setting data
High speed screw H (basis setting)
– without limiter cap, service shop: Open 11/2 turns
– with limiter cap, user: 3/4 turn counterclockwise
Low speed screw L
(standard setting): 3/4 turn counterclockwise
Idle speed screw LA: as required, the chain must not turn

Fuel tank capacity: 11.5 fl.oz. (0.34 l)
Fuel mixture: See instruction manual
Fuel mix ratio: 50:1

2.3 Ignition System
Ignition module: Electronic magneto ignition
Spark plug (resistor
type): NGK CMR 6 H
Electrode gap: 0.020 in. (0.5 mm)

2.4 Chain Lubrication
Fully-automatic speed-controlled oil pump with rotary piston
Oil tank capacity 7.4 fl.oz. (0.22 l)

2.5 Cutting attachment
STIHL Duromatic™ C guide bar
Cutting length 10 in. (25 cm)
Pitch 1/4" (6.36 mm)
Groove width 0.050 in. (1.3 mm)

STIHL 1/4" Rapid™ Micro™ Special (13 RMS) chain
Pitch 1/4" (6.36 mm)
Drive link gauge 0.050 in. (1.3 mm)

Chain sprocket
8-tooth for 1/4" (spur sprocket)

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2.6 Weight
Weight (dry, without bar and chain)
HT 56 C-E 14.8 lbs. (6.7 kg)

2.7 Length
with cutting attachment
HT 56 C-E about 9.2 ft. (280 cm)

3. Special Accessory
30° angle drive

1 2

386TI003 KN
The 30° angle drive 4138 640 0201 is available for For cutting vertical branches and bushes
applications in which an angled cutting attachment horizontally (position 1) or for a better view and
offers advantages. control of the cutting attachment (position 2).

4. Servicing Accessories

4.1 Special servicing tools
Special servicing tools are listed in the STIHL Series
4144 Powerhead, STIHL Series 4144 Components
and STIHL KombiTools shop manuals. No
additional special servicing tools are required for the
HT 56 C-E.

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Technical Information 03.2010 Page 7

4.2 Servicing aids

Description Part No. Application
Starter rope, 39.8 in. (1010 mm) 4237 195 8200 Rewind starter

Carburetor parts kit 4241 007 1002 Zama C1M-S145

STIHL lubricating grease
– 8 oz. (225 g) tube 0781 120 1111 Driver in drive tube

STIHL gear lubricant for
hedge trimmers Shaft in drive tube and hub of clutch drum
– 3 oz. (80 g) tube 0781 120 1109
– 8 oz. (225 g) tube 0781 120 1110

STIHL assembly paste Paste contains molybdenum sulfide and
– 1.8 oz. (50 g) tube 0781 130 1014 graphite; for lubricaton between crankshaft
stub and clutch drum
STIHL special oil Rewind spring
– 3.4 fl.oz. (100 ml) bottle 0781 417 1315 Bearing bore in rope rotor

Standard commercial solvent-based Cleaning crankshaft stubs and flywheel taper
degreasant containing no chlorinated or (see TI 25.2005)
halogenated hydrocarbons

5. Note on Assembly
The pole pruner comes from the factory with the two
halves of the drive tube (boom) packed separately in
the carton and must be completely assembled
before it is used – see also "Assembling the Unit" in
the instruction manual.
Use only the drive tube with splined coupling
supplied with the unit.
KombiTools cannot be mounted to the unit.

6. Spare Parts
Separate spare parts documentation will be
available for the market launch of the HT 56 C-E.

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7. Repairs

7.1 Service manuals
The following service manuals can be used for
repairs to the HT 56 C-E pole pruner:

Engine (4144 Powerhead) Gearbox and
and rear drive tube front drive tube
Service manual Service manual Service manual
Series 4144 Powerhead Series 4144 Components KombiTools
0455 938 0123 0455 545 0123 0455 227 0123

Additional repair procedures are described in this
document.

7.2 Tightening torques 7.4 Service Notes
The tightening torques are listed in the service
manuals. 7.4.1 Hose barb connectors on carburetor

7.3 Starting after a long period of storage
Problems with starting may be experienced if the
machine is stored for several months at
temperatures below 40°F (5°C).
In such a case, press the manual fuel pump several
times to prime the carburetor. Then wait a few
minutes before attempting to start the engine.
Recommendation: Before storing for a prolonged

546TI009 KN
period, always run the engine until the carburetor is
dry. This helps to maintain the integrity of the
carburetor diaphragms – see also chapter on
"Storing the Machine" in the instruction manual. The carburetor has two hose barb connectors
(arrows) for the fuel hoses. Observe the following
procedures to guarantee the tightness of the fuel
system:
. To avoid damaging hose barb connectors, pull
off and push on fuel hoses in line with the
connector by hand where possible – do not use
sharp-edged pliers, screwdrivers, etc. and do
not cut open fuel hoses with a knife or similar
tools.
. Do not re-use fuel hoses after removal. Always
replace with new hoses – fuel hoses may be
over-stretched during removal.
. Fit new fuel hoses dry or with the aid of OH 723
press fluid – 0781 957 9000. Other press fluids
are not approved and may result in damage to
the fuel hoses.
. Coat the ends of the hose and the connectors
with OH 723 press fluid and push the new hoses
onto the hose barb connectors.

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Technical Information 03.2010 Page 9

Note on OH 723 press fluid 7.4.3 Lubricating the clutch drum
OH 723 press fluid produces a lubricating film which The hub of the clutch drum must be re-lubricated as
simplifies assembly. The lubricant evaporates after necessary with gear lubricant for hedge trimmers
a short period – the hose is then tight. 0781 120 1109 or 0781 120 1110 in order to avoid
an increased rate of wear in the clutch drum.
Never use fuel, oil or grease as a lubricant for this
purpose. Fuel, oil and grease do not evaporate – the
hose may loosen or become detached.

7.4.2 Mounting the clutch drum

4907TI007 KN
Lubricate the hub at the point marked (arrow) with
0.01 - 0.02 oz. (0.3 - 0.6 g) grease.
546TI010 KN

7.4.4 Front drive tube
Disassembling
The crankshaft stub (arrow) must be lubricated with
assembly paste 0781 130 1014 before mounting The drive shaft runs in a flexible liner in the drive
the clutch drum (1). tube. The upper end of the drive tube is sealed with
a plug and the lower end with a sleeve.
. Remove the gearbox – see STIHL KombiTool
service manual.

a 2
3

2
546TI011 KN

1
4907TI001 KN

Coat the area of the crankshaft stub (2) marked
"a" = 0.4 in. (10 mm) with assembly paste.
Note on using assembly paste: If no assembly
paste is applied to the crankshaft stub or the . Loosen the star knob (1) and pull the drive
carburetor is not properly adjusted, the cutting tube (2) out of the rear drive tube's coupling
attachment may run while the engine is idling. sleeve (3).
If the cutting attachment continues to run when the
engine is idling, check that carburetor is properly
adjusted and make sure assembly paste has been
applied to the crankshaft stub.

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4907TI002 KN

4907TI004 KN
6 9

. Press down the lug (4) and hold it there. . Pull the flexible liner (9) out of the drive tube.
. Pull the polymer sleeve (5) out of the drive tube.
. Pull the drive shaft (6) out of the drive tube. Assembling
If the drive shaft has turned blue, always install a
new one.
a

7 2

4907TI005 KN
4907TI021 KN

. Push the flexible liner (1) into the drive tube (end
with plug) until it is recessed "a" = 0.80 in.
. Heat the metal sleeve (7) with a hot air blower (20 mm).
and remove it. . Fit the plug (2).

3
4907TI022 KN
4907TI003 KN

. Pull the plug (8) out of the drive tube. . Heat the metal sleeve (3) to about 120°F
(50°C), push it on to the drive shaft (4) and
press it on to the knurling (arrow).
Before installing the drive shaft, coat it with STIHL
gear lubricant for hedge trimmers. Apply the
lubricant uniformly to the drive shaft. Do not pump
lubricant directly into the drive tube.

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Technical Information 03.2010 Page 11

4
3

4907TI008 KN
4907TI018 KN
. Push the drive shaft (4) into the flexible . Loosen the screw (1).
liner (arrow). . Pull the coupling sleeve (2) off the drive
tube (3).

6 5
4907TI006 KN

4907TI009 KN
4
. Press down the lug (5) and push home the
polymer sleeve (6) as far as stop.
. Pull the drive shaft (4) out of the drive tube.
The lug must engage properly, turn the sleeve back
and forth if necessary.
. Install the gearbox – see STIHL KombiTool
service manual.
5
. Check operation – rotate the drive shaft, the saw
chain at the other end must rotate too.

7.4.5 Rear drive tube
Disassembling
4907TI010 KN

. Remove front drive tube – see b 7.4.4
. Remove the drive tube – see STIHL Series 4144
Components service manual. . Pry the plug (5) out of the drive tube.

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2
1

4907TI011 KN

4907TI014 KN
6

. Pull the flexible liner (6) out of the drive tube. . Fit the washer and push the bushing (1) onto the
driver (2) as far as stop.

7
8
3
4
4907TI012 KN

4907TI015 KN
. Grip the collar and pull the complete bushing (7)
out of the drive tube. . Fit the washer (3).
Do not apply tool to polymer lug (8) since it might . Fit the E-clip (4).
break.

1
11 5

10
9
4907TI016 KN
4907TI013 KN

. Fit the bushing (1) in the drive tube, engage the
. Remove the circlip (9). lug (5) in the notch (arrow) and push the
. Remove the washer (10), bushing (11) and the bushing fully home.
second washer.

Assembling
. Coat needle bearing in bushing and shank of
driver with STIHL lubricating grease.

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Technical Information 03.2010 Page 13

b
9

10
6

4907TI017 KN

4907TI020 KN
. Push the flexible liner (6) into the end of the . Fit the coupling sleeve (9) on the end of the
drive tube with the cross hole (arrow) until it is driver. The gap in the clamp must point down.
recessed "b" = 0.90 in. (23 mm). Slide the coupling sleeve onto the drive tube as
. Push the plug (7) into the drive tube as far as far as stop.
stop. . Tighten down the screw (10) firmly.
The drive shaft is supported in the flexible liner . Install the drive tube – see STIHL Series 4144
inside the drive tube. If the drive shaft has turned Components service manual.
blue, install a new one.
Make sure the setscrew that secures the drive tube
Before installing the drive shaft, coat it with STIHL in the engine housing is properly engaged. The
gear lubricant for hedge trimmers. Apply the holes in the drive tube and engine housing must be
lubricant uniformly to the drive shaft. Do not pump in alignment – see STIHL Series 4144 Components
lubricant directly into the drive tube. service manual.

7.5 Serial number

8
4907TI019 KN

546TI005 KN

. Push the drive shaft (8) into the flexible
liner (arrow) until it engages the driver.
The serial number is applied to the underside of the
. Check operation – rotate the drive shaft, the
engine housing in the two positions shown in the
driver at the other end must rotate too.
illustration.

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7.6 Repair Times
Code Type of Repair HT 56 C-E
The specified repair times assume that the work is
performed by trained personnel in a properly 2 Replace crankcase, crankcase 50
equipped service workshop. gasket or re-seal crankcase.
Includes air leak test.
Repair times are quoted in minutes.
3 Replace crankshaft main 50
The following table for the HT 56 C-E can be added bearing(s). Includes air leak
to the STIHL repair times tables. test.
4 Replace crankshaft seal(s). 50
Includes air leak test.
5 Perform engine air leak test. 30
6 Replace cylinder and/or piston. 50
Includes air leak test and repair
of components causing failure.
7 Replace ignition module or 30
flywheel. Includes stop circuit
test.
8 Replace fuel tank line, tank 20
vent, or fuel pick-up body.
9 Replace intake manifold or 20
intake flange.
10 Repair or replace carburetor. 30
Includes fuel system testing.
11 Repair throttle control. 20
12 Repair or replace rewind starter. 15
13 Repair or replace clutch, clutch 30
shoes or clutch springs.
14 Replace muffler. 15
15 Replace air filter or filter 15
housing.
16 Repair or replace stop switch. 25
Includes circuit testing.
17 Replace clutch housing. 20
18 Replace drive shaft and/or drive 30
tube assembly.
19 Replace bearings or liner in 20
drive tube.
20 Replace chain sprocket. 15
21 Replace gearbox assembly. 15
22 Replace fuel tank or oil tank. 20
26 Replace gears and/or bearings 30
in gearbox.
27 Repair or replace oil pump. 25
Includes oil output test.
40 Miscellaneous repairs and other 15
repairs not listed.
45 Handling allowance only-no 10
labor
50 No Labor 0

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