DURKOPP ADLER 838 Operating instructions

838
Spezialnähmaschine
Serviceanleitung
Service Instructions
Postfach 17 03 51, D-33703 Bielefeld • Potsdamer Straße 190, D-33719 Bielefeld
Telefon +49 (0) 521 / 9 25-00 • Telefax +49 (0) 521 / 9 25 24 35 • www.duerkopp-adler.com
Ausgabe / Edition: Änderungsindex Teile-Nr./Part.-No.:
06/2008 Rev. index: 00.0 Printed in Federal Republic of Germany 0791 838641
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Eigentum der Dürkopp Adler AG und urheberrechtlich geschützt. Jede, auch auszugsweise Wiederverwendung
dieser Inhalte ist ohne vorheriges schriftliches Einverständnis der Dürkopp Adler AG verboten.
All rights reserved.
Property of Dürkopp Adler AG and copyrighted. Reproduction or publication of the content in any manner, even
in extracts, without prior written permission of Dürkopp Adler AG, is prohibited.
Copyright © Dürkopp Adler AG - 2008

General safety instructions
The non-observance of the following safety instructions can cause
bodily injuries or damages to the machine.
1. The machine must only be commissioned in full knowledge of the
instruction book and operated by persons with appropriate training.
2. Before putting into service also read the safety rules and
instructions of the motor supplier.
3. The machine must be used only for the purpose intended. Use of
the machine without the safety devices is not permitted. Observe all
the relevant safety regulations.
4. When gauge parts are exchanged (e.g. needle, presser foot, needle
plate, feed dog and bobbin) when threading, when the workplace is
left, and during service work, the machine must be disconnected
from the mains by switching off the master switch or disconnecting
the mains plug.
5. Daily servicing work must be carried out only by appropriately
trained persons.
6. Repairs, conversion and special maintenance work must only be
carried out by technicians or persons with appropriate training.
7. For service or repair work on pneumatic systems, disconnect the
machine from the compressed air supply system (max. 7-10 bar).
Before disconnecting, reduce the pressure of the maintenance unit.
Exceptions to this are only adjustments and functions checks made
by appropriately trained technicians.
8. Work on the electrical equipment must be carried out only by
electricians or appropriately trained persons.
9. Work on parts and systems under electric current is not permitted,
except as specified in regulations DIN VDE 0105.
10. Conversion or changes to the machine must be authorized by us
and made only in adherence to all safety regulations.
11. For repairs, only replacement parts approved by us must be used.
12. Commissioning of the sewing head is prohibited until such time as
the entire sewing unit is found to comply with EC directives.
13. The line cord should be equipped with a country-specific mains
plug. This work must be carried out by appropriately trained
technicians (see paragraph 8).
It is absolutely necessary to respect the safety
instructions marked by these signs.
Danger of bodily injuries !
Please note also the general safety instructions.

Contents Page:
Service Instructions for the Class 838
(Edition 06/2008)
1. General
1.1 Setting gauges ................................................ 3
1.2 Adjusting the handwheel .......................................... 4
2. Bottom feed
2.1 Base setting for stitch adjustment and stitch length limit ....................... 5
2.2 Stitchuniformityforforwardsandreversestitching.......................... 6
2.3 Adjustingtheleversontherearfeedshaft................................ 7
2.4 Position of the eccentric tappet for the feed movement ........................ 8
2.5 Position of the eccentric tappet and the feed dog stroke ....................... 9
2.6 Switchingoverthefeedclutch....................................... 10
2.7 Position of the eccentric tappet for the switch over of the feed clutch ............... 11
2.8 Checkingtheswitchoverofthefeedclutch............................... 12
2.9 Feeddog.................................................... 13
3. Top feed
3.1 Positioning the needle holder for single-needle sewing machines ................. 14
3.2 The needle feed ............................................... 16
3.3 Toproller.................................................... 18
3.4 Liftingthetoproller ............................................. 19
3.5 Press pad for the double-needle sewing machine ........................... 20
4. Adjusting the needle bar and the hook
4.1 Hookheight.................................................. 21
4.2 Needle bar height, play of needle to hook tip, loop stroke ...................... 22
4.3 Protection for the hook tip and loop former ............................... 23
4.4 Bobbin housing lift .............................................. 24
4.5 Hooklubrication ............................................... 25
5. Adjusting the thread
5.1 Thread regulator, thread take-up lever, bolt for the thread lever mechanism ........... 26
5.2 Bobbin Winder ................................................ 27
6. Thread trimmer
6.1 Height of the thread trimming blade. Position of the counter-knife ................. 28
6.2 Startingpositionforthethreadtake-upknife.............................. 29
6.3 Controlcam.................................................. 30
6.4 Bobbin thread clamp............................................. 31
7. Electronic control and machine drive – positioning drive .................... 32

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1. General
These service instructions describe the adjustments that can be made
to the Class 838 special sewing machine.
CAUTION!
The operations described in these service instructions may only be
carried out by qualified staff or other appropriately trained persons!
Caution: Risk of Injury!
Turn the main switch off for repair, conversion and maintenance work
and separate the machine from the pneumatic supply line.
Any adjustment work and functional testing with the machine running
should be conducted only under observance of all safety measures
and with the greatest possible caution.
These service instructions describe the adjustment of the sewing
machine in a logical order. Please observe that various setting
positions are dependent on each other. Thus it is essential that the
settings be conducted while keeping to the order described.
For all adjustments of parts involved in the stitch formation, a new
undamaged needle must be inserted.
This text does not specifically mention any machine covers or panels
which must be removed or re-mounted in order to conduct inspections
or adjustments.
Note
Some shafts on the special 838 machine are provided with flat
eccentric surfaces. This significantly simplifies machine adjustments.
For all adjustments on flat surfaces, the first screw screwed in the
direction of the eccentric surface.
1.1 Setting gauges
The retention pin required for adjusting the machine in included with all
units. It is located with the machine accessories and can be attached
so that it is easily accessible below the oil tray.

1.2 Adjusting the handwheel
Rule:
The handwheel (4) is labelled with degree numbers.
Certain adjustments are made with these marked handwheel positions.
–Turn the handwheel until the degree value specified in the
instructions is aligned with the pointer (3).
–Proceed with the adjustment described.
When the needle bar is at top dead centre, the pointer (3) should be
aligned with“0” degrees.
–Loosen the handwheel screws with a 3-mm hexagon socket
wrench (1).
–Position the needle bar in the top dead centre position. Use the
retention pin (3 mm diameter) to peg the position (2).
–Turn the handwheel so that the pointer (3) points to 0 degrees on
the rotary scale.
–Tighten the first screw with the wrench (1). Turn the handwheel
to 50° and tighten the second screw with the wrench (1).
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2. Lower (bottom) feed
2.1 Base setting for stitch adjustment and stitch length limit
Rules:
1. When setting the stitch length at “0”, the stitch regulator gear should
have as little play (clearance) as possible when you press down on
the bartacking lever.
2. The maximum stitch length is limited to 8 mm.
–Loosen screw (1) and take off the settings dial (2).
–Turn the screw (3) as far as needed to the right using a 10-mm
spanner wrench. Verify that the stitch regulator gear is without
motion by pressing down on the bartacking lever. This fulfils rule 1.
–Set the scaling ring (4) with stitch length 0 to align with the circular
mark (5).
–Limit the stitch length according to rule 2. For this, screw the
retention pin (6) into the proper hole. The holes are marked with
numbers which indicate the maximum stitch length.
–If a maximum stitch length of 7 mm is required, unscrew the screw
(6) for 2.5 mm. Another end stop is available for this length.
–Put the settings dial (2) back on and tighten the screw (1).
Caution: Risk of Injury!
Turnthemainswitchoff.
Only carry out this stitch adjustment when the machine is turned off.
ATTENTION: Danger of breakage!
If the set stitch length is larger than allowed by the sewing equipment
in use, then the needle will hit against the throat plate insert.
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2.2 Stitch uniformity for forwards and reverse stitching
Rules:
1. When making a rough-scale adjustment to the stitch regulator gear,
the machine should not feed when the stitch length is set to 0.
2. When making a fine-scale adjustment to the stitch regulator gear,
the forwards and reverse stitch lengths should only deviate in value by
a half stitch.
–Set the stitch length to “0”.
–Loosen screw (1) and turn the grooved (3) eccentric tappet (2)
according to the illustration. Fasten with screw (1).
–Loosen screw (4) on the clamping lever. Turn the settings frame (5)
so that the shackles (6) are parallel. Tighten screw (4). This then
fulfils rule 1.
–The next step is to match up the forwards and reverse stitch
lengths. Sew ten stitches forwards. Press the bartacking lever and
then sew ten stitches backwards. Rotate the eccentric tappet (2) so
that rule 2 is met.
–Clockwise = enlarge forward stitch, decrease reverse stitch.
–Counter-clockwise = decrease forward stitch, enlarge reverse stitch.
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