Pfaff 918 User manual

296-12-18 759/002
Betriebsanleitung engl. 06.03
Instruction Manual
918 U
938 U
This instruction manual applies to machines from the
following serial numbers onwards:
# 2671899

This instruction manual applies to all versions and subclasses listed under
"Specifications".
Reprinting, copying or translation of PFAFF instruction manuals, whether in whole or in part, is
not permitted without our prior permission and not without written indication of the source.
PFAFF Industrie Maschinen AG
Postfach 3020
D-67653 Kaiserslautern
Königstr. 154
D-67655 Kaiserslautern
Editing/illustrations
HAAS-Publikationen GmbH
D-53840 Troisdorf

Contents
Contents ................................................................................. Chapter – Page
1Safety ............................................................................................................................ 1 - 1
1.01 Regulations ................................................................................................................... 1 - 1
1.02 General notes on safety ................................................................................................. 1 - 1
1.03 Safety symbols ............................................................................................................. 1 -2
1.04 Important notes for the user .......................................................................................... 1 - 2
1.05 Notes for operating and technical staff ........................................................................... 1 - 3
1.05.01 Operating staff ............................................................................................................... 1 - 3
1.05.02 Technical staff ............................................................................................................... 1 -3
1.06 Danger ........................................................................................................................... 1 - 4
2Proper use .................................................................................................................... 2 -1
3Specifications .............................................................................................................. 3 - 1
4Disposal of Machine .................................................................................................... 4 - 1
5Transportation, packing and storage ......................................................................... 5 - 1
5.01 Transportation to customer's premises ......................................................................... 5 - 1
5.02 Transportation inside the customer's premises ............................................................. 5 - 1
5.03 Disposal of packing materials ........................................................................................ 5 - 1
5.04 Storage .......................................................................................................................... 5 - 1
6Explanation of symbols ............................................................................................... 6 - 1
7Controls........................................................................................................................7- 1
7.01 Main switch ..................................................................................................................7- 1
7.02 Keys on the machine head ............................................................................................ 7 - 1
7.03 Pedal ............................................................................................................................. 7 - 2
7.04 Lever for raising presser foot ......................................................................................... 7 - 2
7.05 Adjustment lever for zigzag stitch and needle position ................................................... 7 - 3
7.06 Reverse-feed key .......................................................................................................... 7 - 3
7.07 Stitch length adjustment wheel ..................................................................................... 7 - 4
7.08 Adjustment wheel for multi-stitch and zigzag stitch ....................................................... 7 - 4
7.09 Control panel ................................................................................................................. 7 - 5
7.09.01 Screen displays ............................................................................................................. 7 - 5
7.09.02 Function keys ................................................................................................................ 7 - 5
8Installation and commissioning ................................................................................. 8 - 1
8.01 Installation ..................................................................................................................... 8 - 1
8.01.01 Adjusting the table height .............................................................................................. 8 - 1
8.01.02 Mounting the upper V-belt guard .................................................................................... 8 - 2
8.01.03 Fitting the reel stand ...................................................................................................... 8 - 2
8.02 Mounting the flange motor ............................................................................................. 8 - 3
8.03 Mounting the belt guard of the flange motor .................................................................. 8 - 3
8.04 Connecting the plug-in connections and earth cables ..................................................... 8 - 4

Contents
Contents ................................................................................. Chapter – Page
8.05 Commissioning ............................................................................................................. 8 - 5
8.06 Switching the machine on/off ........................................................................................ 8 - 5
8.07 Basic setting of the machine drive unit .......................................................................... 8 - 6
8.08 Mounting/connecting the start inhibitor .......................................................................... 8 - 8
9Setting up..................................................................................................................... 9- 1
9.01 Inserting the needle ....................................................................................................... 9 -1
9.02 Winding the bobbin thread; adjusting the primary thread tension ................................... 9 - 2
9.03 Removing/inserting the bobbin case .............................................................................. 9 - 3
9.04 Threading the bobbin case, adjusting the thread tension ................................................ 9 - 3
9.04.01 PFAFF 938 without thread trimmer ................................................................................ 9 - 3
9.04.02 PFAFF 938 with thread trimmer ..................................................................................... 9 - 4
9.04.03 PFAFF 918 ..................................................................................................................... 9 - 4
9.05 Threading the needle thread / Adjusting the needle thread tension ................................. 9 - 5
9.06 Setting the zigzag stitch and the stitch position ............................................................. 9 - 6
9.07 Adjusting the stitch length ............................................................................................. 9 - 6
9.08 Adjusting the multi-stitch or the zigzag stitch ................................................................. 9 - 7
9.08.01 Changing from zigzag stitch to multi-stitch .................................................................... 9 - 7
9.08.02 Changing from multi-stitch to zigzag stitch .................................................................... 9 - 7
9.09 Entering the start and end backtacks ............................................................................. 9 - 8
10 Sewing ........................................................................................................................10- 1
10.01 Darning program ...........................................................................................................10 -2
10.02 Counted seam ..............................................................................................................10 -2
10.03 Error messages ............................................................................................................10 -3
11 Care and maintenance ................................................................................................ 11 - 1
11.01 Cleaning ....................................................................................................................... 11 - 1
11.02 Lubricating the hook ..................................................................................................... 11 - 2
11.03 Oiling the zigzag drive ...................................................................................................11 -3
11.04 Cleaning the air filter of the air-filter / lubricator .............................................................11 - 4
11.05 Checking/adjusting the air pressure ..............................................................................11 - 4
12 Adjustment ..................................................................................................................12 - 1
12.01 Notes on adjustment .................................................................................................... 12 - 1
12.02 Tools, gauges and other accessories for adjusting........................................................ 12 - 1
12.03 Abbreviations ................................................................................................................12 - 1
12.04 Check and adjustment aid ............................................................................................12 - 2
12.05 Adjusting the basic machine.........................................................................................12 - 3
12.05.01 Balancing weight ..........................................................................................................12 - 3
12.05.02 Centering the needle in the needle hole (in sewing direction) ........................................ 12 - 4
12.05.03 Parallel guiding of the needle bar ..................................................................................12 - 5
12.05.04 Locking lever ................................................................................................................12 - 6
12.05.05 Zero stitch and zigzag stitch scale ................................................................................12 - 7
12.05.06 Centering the needle in the needle hole (crosswise to sewing direction) .......................12 - 8

Contents
Contents ................................................................................. Chapter – Page
12.05.07 Zigzag stitch width ........................................................................................................12 - 9
12.05.08 Multi-stitch movement .................................................................................................12 - 10
12.05.09 Zigzag movement .........................................................................................................12 - 11
12.05.10 Needle position adjustment lever ..................................................................................12 - 12
12.05.11 Zero position of the bottom feed dog (with closed gear box) .........................................12 - 13
12.05.12 Zeroing the bottom feed (with open gearbox) ................................................................12 - 14
12.05.13 Feeding motion of the bottom feed dog ........................................................................12 - 15
12.05.14 Lifting motion of the bottom feed dog ...........................................................................12 - 16
12.05.15 Drive belt in the gearbox housing ..................................................................................12 - 17
12.05.16 Hook bearing bracket ....................................................................................................12 - 18
12.05.17 Hook lubrication ............................................................................................................12 - 19
12.05.18 Pre-adjusting the needle height ..................................................................................... 12 - 20
12.05.19 Needle rise, hook-to-needle clearance and bobbin case positioning-finger ....................12 - 21
12.05.20 Final adjustment of the needle height ...........................................................................12 - 22
12.05.21 Bobbin case opener position .........................................................................................12 - 23
12.05.22 Bobbin case opener motion ..........................................................................................12 - 24
12.05.23 Bottom feed dog height ................................................................................................12 - 25
12.05.24 Presser foot to needle plate clearance .......................................................................... 12 - 26
12.05.25 Presser foot pressure ...................................................................................................12 - 27
12.05.26 Thread diverter pin ........................................................................................................12 - 28
12.05.27 Limiting the knee lever stroke .......................................................................................12 - 29
12.05.28 Knee lever play .............................................................................................................12 - 30
12.05.29 Bobbin winder ..............................................................................................................12 - 31
12.06 Adjusting the thread trimmer ........................................................................................12 - 32
12.06.01 Axial position of the control cam ..................................................................................12 - 32
12.06.02 Preliminary adjustment of the control cam ...................................................................12 - 33
12.06.03 Position of the thread catcher and cutting test ..............................................................12 - 34
12.06.04 Readjustment of the control cam ..................................................................................12 - 35
12.06.05 Needle thread tension release .......................................................................................12 - 36
12.07 Parameter settings ....................................................................................................... 12 - 37
12.07.01 Selecting the user level .................................................................................................12 - 37
12.07.02 Example of a parameter input .......................................................................................12 - 38
12.07.03 List of parameters ........................................................................................................ 12 - 39
12.08 Reset / Cold start .........................................................................................................12-40
12.09 Explanation of the error signals .....................................................................................12 - 41
12.10 Internet update of the machine software ...................................................................... 12 - 42
13 Wearing parts .............................................................................................................13 - 1
14 Circuit diagrams .........................................................................................................14 - 1

Safety
1 - 1
1 Safety
1.01 Regulations
This machine is constructed in accordance with the European regulations indicated in the
conformity and manufacturer's declarations.
In addition to this instruction manual, please also observe all generally accepted, statutory
and other legal requirements, including those of the user's country, and the applicable pol-
lution control regulations!
The valid regulations of the regional social insurance society for occupational accidents or
other supervisory authorities are to be strictly adhered to!
1.02 General notes on safety
●The machine must only be operated by adequately trained operators and only when the
instruction manual has been fully read and understood!
●All notices on safety and the instruction manual of the motor manufacturer are to be read
before the machine is put into operation!
●All notes on the machine concerning danger and safety must be observed!
●The machine must be used for the purpose for which it is intended and must not be
operated without its safety devices; all regulations relevant to safety must be adhered to.
●When part sets are changed (e.g. needle, presser foot, needle plate, feed dog or bob-bin),
during threading, when the workplace is left unattended and during maintenance work, the
machine must be isolated from the power supply by turning off the on/off switch or
removing the plug from the mains!
●Daily maintenance work must only be carried out by appropriately trained persons!
●Repairs and special maintenance work must only be carried out by qualified technical staff
or persons with appropriate training!
●During maintenance or repairs on the pneumatic system the machine must be isolated
from the compressed air supply! The only exception to this is when adjustments or
function checks are carried out by appropriately trained technical staff!
●Work on the electrical equipment must only be carried out by technical staff who are
qualified to do so!
●Work on parts or equipment connected to the power supply is not permitted! The only
exceptions to this are specified in regulations EN 50110.
●Conversion or modification of the machine must only be carried out under observation of
all relevant safety regulations!

Safety
1 - 2
●Only spare parts which have been approved by us are to be used for repairs! We draw
special attention to the fact that spare parts and accessories not supplied by us have not
been subjected to testing nor approval by us. Fitting and/or use of any such parts may
cause negative changes to the design characteristics of the machine. We shall not ac-cept
any liability for damage caused by the use of non-original parts.
1.03 Safety symbols
Danger!
Special points to observe.
Danger of injury to operating or technical staff!
Electric voltage!
Danger to operating or technical staff!
Caution
Do not operate without finger guard and safety
devices.
Before threading, changing bobbin and needle, cleaning
etc. switch off main switch.
I
1.04 Important notes for the user
●This instruction manual belongs to the equipment of the machine and must be available to
the operating staff at all times.
This instruction manual must be read before the machine is operated for the first time.
●Both operating and technical staff must be instructed on the safety devices of the mach-
ine and on safe working methods.
●It is the duty of the user to operate the machine in perfect running order only.
●The user must ensure that none of the safety devices are removed nor put out of work-ing
order.
●The user must ensure that only authorized persons operate and work on the machine.
For further information please refer to your PFAFF agency.

Safety
1 - 3
1.05 Notes for operating and technical staff
1.05.01 Operating staff
Operating staff are the persons responsible for setting up, operating and cleaning the machine
and for eliminating any malfunctioning in the sewing area.
The operating staff is obliged to observe the following points:
●The notes on safety in this instruction manual must always be observed!
●Any working methods, which adversely affect the safety of the machine, must be
avoided.!
●Loose-fitting clothing should be avoided. No jewellery, such as chains and rings, should be
worn!
●Ensure that only authorised persons enter the danger area of the machine!
●Any changes occurring on the machine, which may affect its safety, must be reported to
the user immediately.
1.05.02 Technical staff
Technical staff are persons who have been trained in electrical engineering/electronics and
mechanical engineering. They are responsible for lubricating, servicing, repairing and adjusting
the machine.
The technical staff is obliged to observe the following points:
●The notes on safety in this instruction manual must always be observed!
●Before carrying out any adjustment or repair work the main switch must be switched off
and measures taken to prevent it from being switched on again!
●Never work on parts or equipment still connected to the power supply! Exceptions are only
permissible in accordance with the regulations EN 50110.
●All safety covers must be replaced after the completion of maintenance or repair work!

Safety
1 - 4
Do not operate the machine without the take-up lever guard 1!
Danger of injury through the movement of the take-up lever.
Do not operate the machine without finger guard 2!
Danger of injury from the needle!
Do not operate machines with integrated motor without start inhibitor 3!
Danger of injury if the machine is started accidentally!
When using an external motor do not operate the machine without belt guard 4!
Danger of injury from the drive belts!
1.06 Danger
A working area of 1 meter is to be kept free both in front of and behind the
machine while it is in operation so that it is always easily accessible.
Never reach into the sewing area while sewing! Danger of injury by the needle!
Never leave objects on the table while adjusting the machine settings!
Objects can become trapped or be slung away!Danger of injury!
Fig. 1 - 01
4
1
92-002
3
2

Proper use
2 - 1
2 Proper use
The PFAFF 918 U is a high-speed zigzag sewing machine with bottom feed, a large hook and
mechanical shift from zigzag to 3-stitch zigzag.
The PFAFF 938 U is a high-speed zigzag sewing machine with bottom feed and mechanical
shift from zigzag to 3-stitch zigzag.
The machines are used for producing zigzag lockstitch seams in the clothing and linen
industry.
Any use of these machines which is not approved by the manufacturer shall be
considered as improper use! The manufacturer shall not be liable for any dam-
age arising out of improper use! Proper use shall also be considered to include
compliance with the operation, adjustment, service and repair measures speci-
fied by the manufacturer!

Specifications
3 - 1
3 Specifications ▲
Stitch type: ........................................................................................ 304 (zigzag lockstitch)
Needle system: .............................................................................................................. 438
Needle size in 1/100 mm:
Model A:.................................................................................................................... 60 - 70
Model B:.................................................................................................................. 80 - 100
Effective balance wheel diameter: ............................................................................ 65 mm
Presser foot clearance: ............................................................................................... 7 mm
Clearance width: .................................................................................................... 260 mm
Clearance height: .................................................................................................... 130 mm
Bedplate dimensions: .................................................................................... 476 x 177 mm
Sewing head dimensions:
Length: ............................................................................................................. ca. 550 mm
Width: ............................................................................................................... ca. 180 mm
Height (above table): ......................................................................................... ca. 300 mm
Max. stitch length:................................................................................................... 4,5 mm
Max. speed:
With 33 mm needle bar stroke: .......................................................................... 4500 spm ◆
Connection data:
Operating voltage: ........................................................................... 230 V ± 10%, 50/60 Hz
Max. power ............................................................................................................. 1,2 kVA
Fuse protection: ............................................................................................. 1 x 16 A, inert
Noise data:
Noise emission level at workplace with a sewing speed of 3600 spm: ... LpA < 78,5 dB(A) ■
(Noise measurement in accordance with DIN 45 635-48-A-1, ISO 11204, ISO 3744, ISO 4871)
Net weight of sewing head: ................................................................................... ca. 46 kg
Gross weight of sewing head: ............................................................................... ca. 54 kg
▲Subject to alterations
◆Depending on the stitch length, the maximum speed is reduced automatically within the max. pre-set value.
■ Kpa = 2.5 dB

Disposal of Machine
4 - 1
4 Disposal of Machine
●Proper disposal of the machine is the responsibility of the customer.
●The materials used for the machine are steel, aluminium, brass and various plastic mat-
erials.
The electrical equipment comprises plastic materials and copper.
●The machine is to be disposed of according to the locally valid pollution control regula-
tions; if necessary, a specialist ist to be commissioned.
Care must be taken that parts soiled with lubricants are disposed of separately
according to the locally valid pollution control regulations!

Transportation, packing and storage
5 - 1
5 Transportation, packing and storage
5.01 Transportation to customer's premises
The machines are delivered completely packed.
5.02 Transportation inside the customer's premises
The manufacturer cannot be made liable for transportation inside the customer's premises nor
to other operating locations. It must be ensured that the machines are only transported in an
upright position.
5.03 Disposal of packing materials
The packing materials of this machine comprise paper, cardboard and VCE fibre. Proper dis-
posal of the packing material is the responsibility of the customer.
5.04 Storage
If the machine is not in use, it can be stored as it is for a period of up to six months, but It
should be protected against dust and moisture.
If the machine is stored for longer periods, the individual parts, especially the surfaces of
moving parts, must be protected against corrosion, e.g. by a film of oil.

Explanation of symbols
6 - 1
6 Explanation of symbols
In this instruction manual, work to be carried out or important information is accentuated by
symbols. These symbols have the following meanings:
Note, information
Cleaning, care
Lubrication
Maintenance, repairs, adjustment, service work
(only to be carried out by technical staff)

Controls
7 - 1
77
-
005
7.02 Keys on the machine head
●As long as key 1is pressed during
sewing, the machine sews in reverse.
●Keys 2and 3can be assigned with the
appropriate parameter settings, see
Motor Instruction Manual.
Fig. 7 - 02
Fig. 7 - 01
7 Controls
7.01 Main switch
●The machine is switched on or off by
turning the main switch 1.
1
04
1
2
3

Controls
7 - 2
7.03 Pedal
0= Neutral position
1= Sewing
2= Raise presser foot
3= Trim thread
Fig. 7 - 03
0
1
23
7.04 Lever for raising presser foot
●The presser foot is raised by turning
lever 1.
Fig. 7 - 04
1

Controls
7 - 3
2
-
006
Fig. 7 - 05
4
M
L
R
2
1
3
7.05 Adjustment lever for zigzag stitch and needle position
●The zigzag stitch adjustment lever 1is
used for adjusting the width of the zigzag
stitch.
●To change the position of the adjustment
lever, the locking lever 2must be pressed
against the adjustment lever 1.
The current zigzag-stitch width
can be seen on scale 3.
●By turning the needle-position adjustment
lever 4the required needle position can be
set.
L= needle-position left
M= needle-position center
R= needle-position right
007
1
Fig. 7 - 06
7.06 Reverse-feed key
●The machine sews in reverse as long as
the reverse-feed key 1is pressed.

Controls
7 - 4
7.07 Stitch length adjustment wheel
●The stitch length can be adjusted by
turning the stitch length adjustment
wheel 1.
The stitch length setting can be
read on scale 2.
008
Fig. 7 - 07
2
1
7.08 Adjustment wheel for multi-stitch and zigzag stitch
Before sewing begins, make
sure that adjustment wheel 1is
locked in position! Only switch
over when the machine is at a
standstill! Danger of machine
damage!
●It is possible to switch between multi
stitch and zigzag stitch with adjustment
wheel 1, see Chapter 9.08 Adjusting the
multi- or zigzag stitch.
Fig. 7 - 08
1

Controls
7 - 5
7.09 Control panel
The control panel consists of display 1and the function keys described below. The display 1
consists of a single-line alpha-numerical, 7 segment LCD display with 8 symbols. The texts 2,
located above and next to the LCD display, show the respective status of the function keys
and the operating status of the machine. The control panels switches on all LCD-segments
and the horn automatically for a short time during the power-on phase, after which the lette-
ring PFAFF appears on the display, until the higher-ranking control unit sends commands to
the control panel.
The function keys are located around the display 1. They are foil-packed without permanent
marking and without contact signal. Fixed functions are allocated to the keys, see Chapter
7.09.02 Function keys.
7.09.01 Screen displays
●Activated functions are displayed with a triangular marking 3below or next to the
respective function key.
●In the sewing mode all relevant sewing data is displayed and can be changed directly,
depending on the status of the machine, see also Chapter 10 Sewing.
●During the parameter input the selected parameter number with the corresponding value is
displayed, see Chapter 12.07.02 Example of a parameter input.
7.09.02 Function keys
The function keys described below are used basically to switch machine functions on and off.
Each time a key is pressed, this must be confirmed by at least one beep tone. Irrespective of
the machine mode a double beep signal is given if invalid keys are pressed or maximum
values reached.
If a corresponding value has to be set for the activated function, this is carried out with the
corresponding +/- key. By pressing and holding the corresponding +/- key, the relevant
numerical value 4is changed slowly to begin with. If the corresponding +/- key is held down
longer, the values change more quickly.
ABCD
3333
1
2
3
SPEED TE ERROR
4

Controls
7 - 6
Start backtacks
●If this key is pressed, the backtacks at the beginning of the seam (start backtacks) are
switched on or off. The number of forward stitches (A) or reverse stitches (B) for the start
backtacks can be changed by pressing the +/- key underneath. To convert from double
backtack to single backtack set the number of stitches for the corresponding seam section
at zero.
End backtacks
●If this key is pressed, the backtacks at the end of the seam (end backtacks) are switched
on or off. The number of reverse stitches (C) or forward stitches (D) can be changed by
pressing the +/- key underneath. To convert from double backtack to single backtack set
the number of stitches for the corresponding seam section at zero.
Needle position
●If this key is pressed the "needle raised after sewing stop" function is switched on or off.
When the function is switched on, the needle positions at t.d.c. after sewing stops.
Foot position after stop
●If this key is pressed the "foot raised after sewing stop" function is switched on or off.
When the function is switched on, the presser foot is raised after sewing stops.
Foot position after trimming
●If this key is pressed the "foot raised after thread trimming" function is switched on or off.
When the function is switched on, the presser foot is raised after thread trimming.
Thread trimmer
●If this key is pressed the thread trimming function is switched on or off.
Darning program
●If this key is pressed the darning program function is switched on or off. The counted
seam function is switched off automatically.
Counted seam
●If this key is pressed the counted seam function is switched on or off. The darning pro-
gram function is switched off automatically.
TE/Speed
●If this key is pressed once the speed limit for the sewing mode is activated.
●If this key is pressed twice (within 5 seconds) the machine changes from sewing to input
mode.