Dürkopp Adler 838 Operating instructions

838
Service Instructions

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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 - 2015

Introduction
This service booklet contains the instructions for setting the sewing machine
head mechanisms.
The directions for putting the machine into operation and for setting the
positioning drive are contained in another publication.
The service booklet is common for all subclasses of the machine and
contains also the instructions for setting optional accessories of the machine,
if this is necessary owing to their complexity. Provided the machine supplied
does not contain some elements, then the respective chapters may be
ignored.
The succession of the setting operations is expressed here by sequencing
the paragraphs of this booklet. When setting, check up, if the setting
operations related to this setting have already been performed.

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.

Index Page
Service Instructions for the Class 838
(Edition 09.2015)
1 General
1.1 Setting gauges ................................................ 5
1.2 Adjusting the handwheel .......................................... 6
1.2.1 Sewingmachinewithminimotor...................................... 6
1.2.2 Sewingmachinewithdirectdrive..................................... 7
2. Bottom feed
2.1 Basic setting for stitch adjustment and stitch length limit ....................... 8
2.2 Stitchuniformityforforwardsandreversestitching.......................... 9
2.3 Adjustingtheleversontherearfeedshaft ............................... 10
2.4 Position of the eccentric tappet for the feed movement ........................ 11
2.5 Position of the eccentric tappet and the feed dog stroke ....................... 12
2.6 Switchingoverthefeedclutch ...................................... 13
2.7 Position of the eccentric tappet for the switch over of the feed clutch ............... 14
2.8 Checkingtheswitchoverofthefeedclutch .............................. 15
2.9 Feeddog.................................................... 16
2.10 Balanceweight................................................ 17
3 Top feed
3.1 Position of the needle holder for single needle sewing machines .................. 19
3.2 Needle bar holder .............................................. 20
3.3 Toproller.................................................... 22
3.4 Liftingthetoproller ............................................. 23
3.5 Fabric holder for double needle sewing machines ........................... 24
4 Setting the needle bar and the hook
4.1 Hookheight.................................................. 25
4.2 Needle bar height, play of needle to hook tip, loop stroke ...................... 26
4.3 Hook tip guard and loop former ...................................... 27
4.4 Bobbin housing release ........................................... 28
4.2 Hooklubrication ............................................... 29
5 Thread setting
5.1 Thread regulator, check spring, bolt for the thread lever mechanism................ 30
5.2 Bobbin winder................................................. 31
6 Thread cutter
6.1 Thread cutter height, position of the counter knife ........................... 32
6.2 Starting position for the thread pulling knife............................... 33
6.3 Controlcam.................................................. 34
6.4 Bobbin thread clamp............................................. 35
EN

Index Page
7. Electronic control and sewing machine drive - positioning motor ............... 36
7.1 Terminals to PCB connections - electromagnetic variant ....................... 37
7.2 Terminals to PCB connections - pneumatic variant .......................... 38

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.
5
EN

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.
1.2.1 Sewing machines with minimotor
–Loosen the handwheel screws witha3mmAllenkey(1).
–Position the needle bar in the upper 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 Allen key (1). Turn the handwheel
to 50° and tighten the second screw with the Allen key (1).
6
1
3
2
4

1.2.2 Sewing machine with direct drive
–Unscrew three fixing screws on the hand wheel (5) and remove it.
–Put the needle in the upper dead point and insert the setting pin
(2), which is a part of the sewing machine accessories and which is
fixed on the oil tray bottom side, into the crank head.
–Loosen two setting screws of the hand wheel flange (4) with the
Allenkey3mm(1).
–Turn the hand wheel flange with the hollow (6) against the sign (3).
–Tighten both setting screws with the key (1) and fix the hand wheel
on again.
7
EN
24
1
36
5

2 Bottom feed
2.1 Basic setting for stitch adjustment and stitch length limit
Rule:
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
open-ended 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”toalignwiththe
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.
–Put the settings dial (2) back on and tighten the screw (1).
Caution: Risk of injury!
Turnthemainswitchoff.
Only carry out this basic stitch adjustment when the machine
is turned off.
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12
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