Technical Information · issue 14 of 1999

HT 75, Servicing: Telescopic shaft; Cutting attach

IssueTI 14/1999

Full text

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Technical Information

14.1999
Servicing Model HT 75 Pole Pruners - Series 4138

This Technical Information bulletin supersedes and replaces TI 03.97.
Inspection and servicing work must be performed by properly trained and authorized personnel.

Contents
1. Telescopic tube
2. Cutting attachment
3. Lubrication

Note: Refer to the illustrated parts - Remove the plastic liner and
list for better orientation during the retaining ring.
following operations.

1. Telescopic tube

390RA003 KN
1.1 Drive shaft
4
The drive shaft consists of an
external splined shaft supported in
390RA035 KN

ball bearings in the fixed part of the Pull out external splined shaft (4).
telescopic tube and an internal
splined shaft supported in the Note: If shaft is damaged or has
plastic liner and ball bearing in the . Release clamp screws on turned blue, fit a new shaft
sliding part of the telescopic tube control handle. assembly (external splined shaft
. and internal splined shaft).
As the internal and external splined
shafts are made to very close 2
tolerances, always replace as a
pair.
- Remove the gearbox - see 2.1
390RA002 KN

390RA036 KN

3
. Unscrew fixing screw (2) from 5 1
AV sleeve.
. Release clamp screw (3). - New shafts are pre-lubricated.
- Pull out the drive tube. Only the internal bore of the
390RA001 KN

plastic liner (5) needs to be
1 lubricated.

. Pull out the internal splined
shaft (1). The plastic liner and
retaining ring come out at the
same time.

TI_14_1999_30_01.fm
U
)m~ge 2 Technical Information 14.1999

Important: Apply a uniform coating 1.2 plastic liner and bearings
of grease (0781 120 6602) to the
outside of the drive shaft. Never A
pump grease directly into the drive
tube.

390BA038 KN

390RA006 KN
4
. Push external splined shaft (4)
into the short drive tube as far . Mark the engine end on the
as stop (A = 11 mm). Only the drive tube’s handle hose.
390RA037 KN

square end of the shaft should
be visible. - Remove the drive shaft, see
1.1. The plastic liner comes out
Note: If the drive shafts have to be Check that internal splined shaft is at the same time.
cleaned before installation, pull the not pushed out while you are fitting
shafts apart. Before reassembling, the external splined shaft.
coat the external splined shaft
completely with STIHL synthetic
two-stroke engine oil. Install as
specified.

. Remove screw from clamp
(harness eye).
. Slide the drive tube into position
390RA005 KN

so that the holes line up. A
1 helper may be needed to turn
the drive shaft while the drive
- Slide ring and plastic liner onto tube is being pushed home. If
the internal splined shaft. necessary, use a screwdriver to
- Telescopic tube must be hold the clutch drum steady
completely compressed to during this process.
simplify assembly.
- Tighten down fixing screw to
. Push internal splined shaft (1) 2.5 Nm (1.8 lbf.ft) and clamp
together with plastic liner and screw to 5 Nm (3.7 lbf.ft).
ring into the drive tube as far as . Pull clamp apart and lift it away.
stop. Turn the shaft to and fro - Install the gearbox - see 2.1
during this process to make
sure that the retaining ring does
not snag on the stop or
mounting rivet. Do not use
force to push shaft fully home.
Only the square end of the shaft
should be visible (see illus.).

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Technical Information 14.1999 Page 3

4
1 12
A B
11
B

390RA042 KN

390RA045 KN
390RA039 KN
3
13
2
. Release the star grip nut (1) - Replace worn bearings. In the case of a new drive tube or
and pull out the long drive tube In case of riveted bearings: one that has no marking, determine
(2). The springs are relaxed. the engine end of the outer drive
. Loosen screws (3) on the clamp . Remove blind rivet (12) and pull tube as follows:
(4). off the bearing (13). Looking through the outer drive
. Pull off the clamp (4). tube (11) from the engine end, the
. Pull out the long drive tube (2) rivet (A) must be at the top and the
at the gearbox end. 12 guides (B) on the right.

6
5 14
390RA043 KN
8
13
8
390RA040 KN

. Holes in the bearing (13) and

390RA046 KN
drive tube (14) must line up.
7 . Secure bearing (13) only with 7
. Loosen screws (5, 6) on the original STIHL blind rivet (12).
. Slip the clamp (7) over the short
clamp (7). drive tube (8).
. Pull off the clamp (7).
. Pull out the drive tube (8) at the
engine end. 9
6
9 11
9 10
390RA044 KN

9 10
390RA047 KN

11
10 At marked engine end of drive tube:
7
390RA041 KN

. Push bearing (10), ball bearing
10 end first, and springs (9) into . Slide both parts into the engine
the outer drive tube (11). end of the outer drive tube.
. Remove the springs (9) and . Tighten down screws (6) on the
bearings (10) from the outer clamp (7).
drive tube (11).

TI_14_1999_30_01.fm
)m~ge 4 Technical Information 14.1999

2. Cutting attachment
5 2.1 Gearbox
8 For versions with friction clutch, 6
also refer to service notes in
TI 36.98.

390RA048 KN

390RA016 KN
5
. Pull out the short drive tube (8) . Take pinion (5) out of gearbox
as far as stop. housing (6).
. Tighten down screw (5).

390RA013 KN
Assembly of the remaining parts is 9
now a reversal of the disassembly
sequence. 8
. Release clamp screws on
gearbox.
1.3 Drive tube . Pull gearbox off the drive tube.

390RA017 KN
- Remove the drive shaft 7
- see 1.1. 1
- Remove the plastic liner and . Use pliers (8) 0811 611 8200 to
bearings - see 1.2. remove retaining ring (7).
. Pull ball bearings (9) off the
- Replace damaged drive tube. pinion.
390RA014 KN

- Remove the chain sprocket
cover and chain sprocket. 6
- Remove the oil tank - see 2.2.
. Slide the ring (1) off the 390RA018 KN
shaft (2).
2

. Take shaft (2) out of the
gearbox housing (6).
4
3

11
2
390RA015 KN

. Remove screws (3) from
390RA019 KN

gearbox cover (4).
. Lift away the gearbox cover (4).

. Pull ball bearings (10 and 11) off
the shaft (2).

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Technical Information 14.1999 Page 5

11
5
2 1
10
6

390RA023 KN

390RA026 KN
390RA020 KN
2

. Press ball bearing (10) onto - Fill cavity in gearbox housing . Push the ring (1) onto the
pinion end of shaft (2). for pinion with 8g gear lubricant. shaft (2).
. Press ball bearing (11) onto the . Fit pinion (5) in gearbox - Slide the gearbox onto the
shaft (2). housing (6). drive tube and turn it back and
forth at the same time so that
the square end of the drive
6 shaft engages the square
recess in the drive pinion.
- Push gearbox as far as stop
and line it up properly.
- Tighten down clamp screws
on gearbox to 6.5 Nm
390RA021 KN

390RA024 KN
2 (4.8 lbf.ft).

. Place shaft (2) in the gearbox . Apply thin coating of Dirko 2.2 Oil tank
housing (6). sealant 0783 830 2120 to
mating face on gearbox
housing.
9

7
3

390RA027 KN
390RA022 KN

4
. Remove oil tank filler cap along
390RA025 KN

with cap retainer.
. Press on ball bearings (9).
. Install retaining ring (7).
. Fit the gearbox cover (4).
. Insert screws (3) in gearbox
cover (4) and tighten down all
but the clamp screws (arrows)
to 6.5 Nm (4.8 lbf.ft).
390RA028 KN

. Remove screws from oil tank.

TI_14_1999_30_01.fm
)m~ge 6 Technical Information 14.1999

3. Lubrication
Further testing has resulted in a
change in the use of lubricants.
The following lubricants should be
used:

3.1 Gearbox

390RA032 KN
390RA029 KN

. Swing oil tank counter- . Line up oil pump as shown by
clockwise and lift it away. the symbol next to the bore.
- Installation is a reversal of Slot must point towards engine.
the removal sequence.

390RA049 KN
2.3 Oil pump

Gear lubricant for brushcutters
(0781 120 1117 / 0781 120 1118)
For notes on lubrication see 2.1.
390RA033 KN
3.2 Drive shafts
2 STIHL synthetic two-stroke engine
oil
390RA030 KN

. Screw an M5 screw into the oil
pump and then press home the For notes on lubrication see 1.1.
1 oil pump.
. Remove the M5 screw. 3.3 Drive shaft in plastic liner
- Remove the oil tank - see 2.2
- Installation of the remaining Grease (0781 120 6602)
. Ease the rubber seal (1) out of parts is a reversal of the For notes on lubrication see 1.1.
the gearbox housing. removal sequence.
. Take out the filter screen (2).

2.4 Chain tensioner

See workshop manual for E 14,
E 20 or E 140, 160, 180 C.
390RA031 KN

. Screw an M5 screw (min.
25mm/1” long) into the oil
pump.
. Use the screw to pull the oil
pump out of the housing.
- Clean the oilpassages.

Last Technical Information on model HT 75 pole pruner: 36.98

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