Pfaff 3734 -12 User manual

Instruction Manual
3734-12/21
296-12-18 750/002
Betriebsanleitung dtsch. 09.03
This instruction manual applies to machines from the
following serial numbers onwards:
# 2648486

This instruction manual applies to all versions and subclasses listed under
"Specifications".
The reprinting, copying or translation of PFAFF Instruction Manuals, whether in whole or in
part, is only permitted with our previous authorisation and with written reference to the
source.
PFAFF Industrie Maschinen AG
Postfach 3020
D-67653 Kaiserslautern
Königstr. 154
D-67655 Kaiserslautern
Redaktion / Illustration
HAAS-Publikationen GmbH
D-53840 Troisdorf

Contents
Contents ..................................................................................Chapter - Page
1Safety ............................................................................................................................ 1- 1
1.01 Directives ...................................................................................................................... 1 - 1
1.02 General notes on safety ................................................................................................. 1 - 1
1.03 Safety symbols ............................................................................................................. 1 -2
1.04 Important points for the user .......................................................................................... 1 - 2
1.05 Operating and specialist personnel ................................................................................ 1 - 3
1.05.01 Operating personnel ....................................................................................................... 1 - 3
1.05.02 Specialist personnel ....................................................................................................... 1 - 3
1.06 Danger ........................................................................................................................... 1 - 4
2Proper use .................................................................................................................... 2 -1
3Specifications .............................................................................................................. 3 - 1
3.01 PFAFF 3734-12/21 ......................................................................................................... 3 - 1
3.02 Model, needles and threads ........................................................................................... 3 - 2
4Disposal of machines .................................................................................................. 4 - 1
5Transport packaging and storage ............................................................................... 5 - 1
5.01 Transport to the customer’s premises ........................................................................... 5 - 1
5.02 Transport within the customer’s premises ..................................................................... 5 - 1
5.03 Disposal of the packaging .............................................................................................. 5 - 1
5.04 Storage .......................................................................................................................... 5 - 1
6Explanation of the symbols ........................................................................................ 6 - 1
7Controls .................................................................................................... 7- 1
7.01 On/off switch ................................................................................................................. 7 - 1
7.02 Pedal ............................................................................................................................. 7 - 1
7.03 Knee switch ..................................................................................................................7- 2
7.04 Lever for raising the feed band ...................................................................................... 7 - 2
7.05 Control panel ................................................................................................................. 7 - 3
7.05.01 Displays on the screen .................................................................................................. 7 - 3
7.05.02 Function keys ................................................................................................................ 7 - 3
8Mounting and commissioning the machine .............................................................. 8 - 1
8.01 Mounting ....................................................................................................................... 8 - 1
8.01.01 Adjusting the table-top height ........................................................................................ 8 - 1
8.01.02 Fitting the tilt lock .......................................................................................................... 8 -2
8.01.03 Fitting the machine cover .............................................................................................. 8 - 2
8.02 Mounting the flange motor ............................................................................................. 8 - 3
8.02.01 Mounting the flange motor to the bearing plate .............................................................. 8 - 3
8.02.02 Mounting the flange motor to the machine .................................................................... 8 - 3
8.02.03 Connecting the plug-in connections and earth cables..................................................... 8 - 4
8.02.04 Mounting the belt guard of the flange motor .................................................................. 8 - 5

Contents
Contents ..................................................................................Chapter - Page
8.02.05 Connecting the safety switch ........................................................................................ 8 - 6
8.02.06 Checking the function of the start inhibitor .................................................................... 8 - 6
8.02.07 Basic position of the machine drive unit ........................................................................ 8 - 7
8.03 Fitting the reel stand ...................................................................................................... 8- 8
8.04 Commissioning ............................................................................................................. 8 - 8
8.05 Switching the machine on/off ........................................................................................ 8 - 8
9Setting up..................................................................................................................... 9- 1
9.01 Inserting the needle ....................................................................................................... 9 -1
9.02 Winding the bobbin thread, adjusting the thread tension ................................................ 9 - 2
9.03 Removing / Inserting the bobbin case ............................................................................ 9 - 3
9.04 Threading the bobbin case / Adjusting the bobbin thread tension ................................... 9 - 3
9.05 Threading the needle thread / Adjusting the needle thread tension ................................. 9 - 4
9.06 Entering the stitch length ............................................................................................... 9 - 5
9.06.01 Entering the standard stitch length ................................................................................ 9 - 5
9.06.02 Entering a second stitch length or amount of fullness .................................................... 9 - 5
9.06.03 Entering the fullness area for the pedal adjustment ....................................................... 9 - 6
9.07 Entering the start and end backtacks ............................................................................. 9 - 7
9.08 Entering/changing the code number ............................................................................... 9 - 8
9.09 Switching on/adjusting the bobbin thread control with reverse stitch count .................. 9 - 10
10 Sewing ........................................................................................................................10- 1
10.01 Manual sewing .............................................................................................................10 -1
10.02 Programmed sewing ....................................................................................................10 - 2
10.03 Altering seam programs ...............................................................................................10 - 3
10.04 Error messages ............................................................................................................10 -4
11 Care and maintenance ...............................................................................................11 - 1
11.01 Cleaning .......................................................................................................................11 - 1
11.02 Oiling the hook ............................................................................................................. 11 - 2
11.03 Checking the oil levels .................................................................................................11 - 2
11.04 Lubricating the bevel gears ...........................................................................................11 - 3
12 Adjustment ..................................................................................................................12 - 1
12.01 Notes on adjustment ....................................................................................................12 - 1
12.02 Werkzeuge, Lehren und sonstige Hilfsmittel ................................................................. 12 - 1
12.03 Abbreviations ................................................................................................................12 - 1
12.04 Adjusting the basic machine .........................................................................................12 - 2
12.04.01 Positioning the needle in the direction of sewing........................................................... 12 - 2
12.04.02 Positioning the needle across the direction of sewing ...................................................12 - 3
12.04.03 Preadjusting the needle height ...................................................................................... 12 - 4
12.04.04 Needle rise, hook-to-needle clearance, needle height and needle guard ........................ 12 - 5
12.04.05 Height and stroke of the bobbin case opener ................................................................12 - 7
12.04.06 Height of the feed wheel ..............................................................................................12 - 8
12.04.07 Clearance between feed band and feed wheel .............................................................12 - 9

Contents
Contents ..................................................................................Chapter - Page
12.04.08 Adjusting the feed band ................................................................................................12 - 10
12.04.09 Changing the feed band ................................................................................................12 - 11
12.04.10 Automatic presser foot lift ............................................................................................12 - 12
12.04.11 Retainer ........................................................................................................................12 - 13
12.04.12 Tension release and tension control .............................................................................12 - 14
12.04.13 Thread check spring ..................................................................................................... 12 - 15
12.04.14 Bobbin winder .............................................................................................................12 - 16
12.04.15 Feed band pressure ......................................................................................................12 - 17
12.04.16 Locking the set value transmitter .................................................................................12 - 18
12.04.17 Lubrication ....................................................................................................................12 - 19
12.04.18 Re-engage safety coupling ...........................................................................................12 - 20
12.05 Adjusting the thread trimmer –900/81 ...........................................................................12 - 21
12.05.01 Resting position of the roller lever / radial position of the control cam ...........................12 - 21
12.05.02 Position of the thread catcher holder .............................................................................12 - 22
12.05.03 Distance between thread catcher and needle plate .......................................................12 - 23
12.05.04 Position of the thread catcher ....................................................................................... 12 - 24
12.05.05 Knife position and knife pressure ..................................................................................12 - 25
12.05.06 Bobbin thread retaining spring .......................................................................................12 - 26
12.05.07 Manual cutting test ..................................................................................................... 12 - 27
12.06 Parameter settings ....................................................................................................... 12 - 28
12.06.01 Overview of the parameter functions ...........................................................................12 - 29
12.06.02 Parameter input example ..............................................................................................12 - 29
12.06.03 List of parameters ........................................................................................................12 - 30
12.07 Explanation of the error messages ...............................................................................12 - 33
12.08 Warning messages ......................................................................................................12 - 33
12.09 Carrying out a cold start ............................................................................................... 12 - 34
12.10 Internet update of the machine software ......................................................................12 - 35
13 Wearing parts .............................................................................................................13 - 1
14 Circuit diagrams .........................................................................................................14 - 1

Safety
1 - 1
1 Safety
1.01 Directives
This machine is constructed in accordance with the European regulations contained in the
conformity and manufacturer’s declarations.
In addition to this Instruction Manual, observe also all generally accepted, statutory and other
regulations and legal requirements and all valid environmental protection regulations!
The regionally valid regulations of the social insurance society for occupational accidents or
other supervisory organisations are to be strictly adhered to!
1.02 General notes on safety
●This machine may only be operated by adequately trained operators and only after having
completely read and understood the Instruction Manual!
●All Notes on Safety and Instruction Manuals of the motor manufacturer are to be read
before operating the machine!
●The danger and safety instructions on the machine itself are to be followed!
●This machine may only be used for the purpose for which it is intended and may not be
operated without its safety devices. All safety regulations relevant to its operation are to be
adhered to.
●When exchanging sewing tools (e.g. needle, roller presser, needle plate, or bobbin), when
threading the machine, when leaving the machine unattended and during maintenance
work, the machine is to be separated from the power supply by switching off the On/Off
switch or by removing the plug from the mains!
●Everyday maintenance work is only to be carried out by appropriately trained personnel!
●Repairs and special maintenance work may only be carried out by qualified service staff or
appropriately trained personnel!
●Work on electrical equipment may only be carried out by appropriately trained personnel!
●Work is not permitted on parts and equipment which are connected to the power supply!
Exceptions to this are only to be found in the regulations EN 50110.
●Modifications and alterations to the machine may only be carried out under observance of
all the relevant safety regulations!
●Only spare parts which have been approved by us are to be used for repairs! We
expressly point out that any replacement parts or accessories which are not supplied by
us have not been tested and approved by us. The installation and/or use of any such
products can lead to negative changes in the structural characteristics of the machine. We
shall not be liable for any damage which may be caused by non-original parts.

Safety
1 - 2
1.03 Safety symbols
Danger!
Points to be observed.
Danger of injury for operating and specialist personnel!
1.04 Important points for the user
●This Instruction Manual is a component part of the machine and must be available to the
operating personnel at all times.
●The Instruction Manual must be read before operating the machine for the first time.
●The operating and specialist personnel is to be instructed as to the safety equipment of the
machine and regarding safe work methods.
●It is the duty of the user to only operate the machine in perfect running order.
●It is the obligation of the user to ensure that none of the safety mechanisms are removed
or deactivated.
●It is the obligation of the user to ensure that only authorized persons operate and work on
the machine.
Further information can be obtained at your PFAFF agent.
Caution
Do not operate without finger guard and safety devices.
Before threading, changing bobbin and needle, cleaning
etc. switch off main switch.
I

Safety
1 - 3
1.05 Operating and specialist personnel
1.05.01 Operating personnel
Operating personnel are persons responsible for the equipping, operating and cleaning of the
machine as well as taking care of faults arising in the sewing area.
The operating personnel is obliged to observe the following points and must:
●always observe the Notes on Safety in the Instruction Manual!
●never use any working methods which could limit the level of safety in using the machine!
●not wear loose-fitting clothing or jewellery such as chains or rings!
●also ensure that only authorized persons have access to the potentially dangerous area
around the machine!
●always immediately report to the person responsible any changes in the machine which
may limit its safety!
1.05.02 Specialist personnel
Specialist personnel are persons with a specialist education in the fields of electrics,
electronics and mechanics. They are responsible for the lubrication, maintenance, repair and
adjustment of the machine.
The specialist personnel is obliged to observe the following points and must:
●always observe the Notes on Safety in the Instruction Manual!
●switch off the On/Off switch before carrying out adjustments or repairs and ensure that it
cannot be switched on again unintentionally!
●never work on parts which are still connected to the power supply! Exceptions are
contained only in the regulations EN 50110.
●replace the protective coverings and close the electrical control box after all repairs or
maintenance work!

Safety
1 - 4
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 or in the needle plate area while adjusting the
machine settings! Objects can become trapped or be slung away! Danger of
injury!
Do not operate the machine without support 1!
Danger due to top-heavy sewing head!
Machine can tip over backwards when tilted!
Do not operate the machine without its take-up-lever guard 2!
Danger of injury due to the motion of the take-up lever!
Do not operate the machine without cover 3!
Danger of injury from moving drive belts!
Do not operate the machine without tilt lock 4!
Danger of crushing between sewing head and table top!
23
4
Fig. 1 - 01 63-021
1

Proper use
2 - 1
2 Proper use
The PFAFF 3734-2/21 is a high-speed, single needle, postbed sewing machine (post to the
right of the needle) with forwards and reverse feeding feed-wheel and roller presser.
This machine is used for sewing lockstitch seams in the clothing industry.
Any and all uses of this machine which have not been approved of by the
manufacturer are considered to be inappropriate! The manufacturer cannot be
held liable for any damage caused by the inappropriate use of the machine! The
appropriate use of the machine includes the observance of all operational,
adjustment, maintenance and repair measures required by the manufacturer!

Specifications
3 - 1
3 Specifications
3.01 PFAFF 3734-12/21▲
Stitch type: ................................................................................................ 301 ( lockstitch )
Roller presser clearance: ............................................................................................ 9 mm
Clearance width: .................................................................................................... 245 mm
Clearance height: .................................................................................................... 115 mm
Post height: ............................................................................................................ 180 mm
Sewing head dimensions:
Length: ....................................................................................................... approx. 615 mm
Width: ......................................................................................................... approx. 240 mm
Height ( above table ): ................................................................................ approx. 500 mm
Bed-plate dimensions: ...................................................................................518 x 177 mm
Max. speed: ................................................................................................... 3500 s.p.m. ◆
Connection data:
Operating voltage: ........................................................................... 230 V ± 10%, 50/60 Hz
Max. power consumption: ....................................................................................... 1,2 kVA
Fuse protection: ............................................................................................. 1 x 16 A, inert
Noise data:
Emission sound level at the workplace at a speed of 2700 spm: ......................... 80 dB(A)■
( Noise measurement in acc. with DIN 45 635-48-A-1, ISO 11204, ISO 3744, ISO 4871 )
Net weight of sewing head: ............................................................................ approx. 61 kg
Gross weight of sewing head: ........................................................................ approx. 71 kg
▲Subject to alternation
◆Varies according to material, work process and stitch length
■KpA = 2,5 dB
3.02 Model, needles and threads
Model: ............................................................................................................................... A
Needle system: ......................................................................................................... 134-35
Needle size in 1/100 mm: ................................................................................................. 80
Max. thread size synthetic *: .................................................................................... 60 - 60
*Or comparable thicknesses of other thread types

Disposal of machines
4 - 1
4 Disposal of machines
●The proper disposal of machines is the responsibility of the customer.
●The materials used in the machines are steel, aluminium, brass and various plastics.
The electrical equipment consists of plastics and copper.
●The machine is to be disposed of in accordance with the locally valid
environmental protection regulations. If necessary, a specialist is to be commissioned.
Special care is to be taken that parts soiled with lubricants are separately
disposed of in accordance with the locally valid pollution control regulations!

Transport packaging and storage
5 - 1
5 Transport packaging and storage
5.01 Transport to the customer’s premises
All machines are delivered completely packed.
5.02 Transport within the customer’s premises
The manufacturer bears no liability for transport within the customer’s premises or to the indi-
vidual locations of use.
Always ensure that the machine is only transported upright.
5.03 Disposal of the packaging
The packaging of these machines consists of paper, cardboard and VCE fibre.
The proper disposal of the packaging is the responsibility of the customer.
5.04 Storage
The machine can be stored for up to 6 months if not in use. During this time it should be
protected from dust and moisture.
For longer storage the individual parts of the machine, especially the moving parts, should be
protected against corrosion, e.g. by a film of oil.

Explanation of the symbols
6 - 1
6 Explanation of the symbols
In the following section of this Instruction Manual, certain tasks or important pieces of
information are accentuated by symbols.
The symbols used have the following meanings:
Note, information
Cleaning, care
Lubrication, greasing
Servicing, repairing, adjustment, maintenance
(only to be carried out by specialist personnel)

Controls
7 - 1
7.02 Pedal
0= Neutral position
1= Sewing
2= Raise roller presser
3= Trim thread and raise roller presser
1 + 4 = Variable application of fullness
8
7-004
77
-
005
Fig. 7 - 01
7Controls
7.01 On/off switch
●Turn the machine on/off by turning
On/Off switch 1.
Fig. 7 - 02
4
01
3
2
1

Controls
7 - 2
87-006
87-004
7.04 Lever for raising the feed band
●Raise the feed band by turning lever 1.
Fig. 7 - 04
7.03 Knee switch
●By operating knee switch 1it is possible
to select 2pre-set values for fullness.
Fig. 7 - 03
1
1

Controls
7 - 3
7.05 Control panel
The control panel consists of display 1and the function keys described below. Display 1
consists of a two-row, alpha-numerical display with 16 symbols per row. The special
symbols 3and texts 4 show the respective status of the function keys and the operating
modes of the machine.
During the power-on phase the control panel automatically switches on all LCD segments
and a beep tone for a short time. Afterwards the lettering PFAFF appears on the display, until
the higher-ranking control unit sends commands to the control panel.
7.05.01 Displays on the screen
●Activated functions are shown with a triangular symbol 2below or next to the respective
function key.
●In sewing mode all relevant sewing data is displayed and can be changed directly
depending on the machine status, also see Chapter 10 Sewing.
●When entering the parameters, the selected parameter number with the corresponding
parameter value is displayed, see Chapter 12.06 Parameter settings.
7.05.02 Function keys
The function keys described below are used basically to switch the machine functions on and
off.
If a value must be given for the activated function, this is entered with the relevant +/- key.
By pressing down the relevant +/- key the corresponding value 5is changed slowly. If the +/-
key is held down longer, the values change more quickly.
Start backtacks
●By pressing this key, the backtacking function at the beginning of the seam (start
backtacks) is switched on or off. The number of forward stitches (A) or reverse stitches
(B) for the start backtacks can be changed in each case by pressing the +/- key
underneath. To convert from double backtacks to single backtacks the relevant number of
stitches for the seam segment is set at zero.
●When entering the code number, the key corresponds to the number 1.
2.5 2.5
PM
5
341 2

Controls
7 - 4
End backtacks
●By pressing this key, the backtacking function at the end of the seam (end backtacks) is
switched on or off. The number of reverse stitches (C) or forward stitches (D) can be
changed in each case by pressing the +/- key underneath. To convert from double
backtacks to single backtacks the relevant number of stitches for the seam segment is
set at zero.
●When entering the code number, the key corresponds to the number 2.
Needle position
●By pressing this key the function "Needle raised after sewing stop" is switched on or off.
When the function is switched on, the needle positions at t.d.c. after sewing stops.
●When entering the code number, the key corresponds to the number 3.
Foot position after stop
●By pressing this key the function "Foot raised after sewing stop" is switched on or off.
When the function is switched on, the sewing foot is raised after sewing stops.
●When entering the code number, the key corresponds to the number 4.
Foot position after trimming
●By pressing this key the function "Foot raised after thread trimming" is switched on or off.
When the function is switched on, the sewing foot is raised after sewing thread trimming.
●When entering the code number, the key corresponds to the number 5.
Thread trimmer
●By pressing this key the thread trimming function is switched on or off.
●When entering the code number, the key corresponds to the number 6.
●When entering the code number, the key corresponds to the number 7.
●When entering the code number, the key corresponds to the number 8.
●When entering the code number, the key corresponds to the number 9.
Stop
●By pressing this key the corresponding function is switched on or off. If the function is
activated, the feed band and feed wheel drive are switched off, in order to e.g. fill the
bobbin thread spool outside the sewing operation.
●When entering the code number, this key corresponds to the number 0.
This key has no function.
This key has no function.

Controls
7 - 5
TE/Speed
●By pressing this key once the speed limitation for sewing mode is activated.
By pressing the key twice ( within 5 seconds ) the machine switches to parameter input mode.
In the parameter input mode the lettering "TE" is displayed on the control panel. In the alpha-
numerical section of the display the parameters are listed with their corresponding values, see
Chapter 12.06 Parameter settings.
Scrolling
●When this key is pressed, it is possible to scroll through the input menus on the display.
PM
●By pressing this key the Programmed Sewing function is switched on or off. When the
function is switched on, the lettering “PM“ appears in the display of the control panel.
The parameters of the programs are shown in the alpha-numerical section of the display.
F1
This key has no function.
F2
This key has no function.
F3
This key has no function.
F4
●After this key has been pressed, the next bartack will not be sewn.

Mounting and commissioning the machine
8 - 1
8 Mounting and commissioning the machine
The machine must only be mounted and commissioned by qualified personnel!
All relevant safety regulations are to be observed!
If the machine is delivered without a table, it must be ensured that the frame
and the table top which you intend to use can hold the weight of the machine
and the motor, even while sewing.
8.01 Mounting
The necessary electricity supply must be available at the machine’s location.
There must be a stable and horizontal surface and adequate lighting at the
machine’s location.
Due to reasons of packaging, the table top is lowered for transport.
The following is a description of how to adjust the height of the table top.
8.01.01 Adjusting the table-top height
●Loosen screws 1and 2and set the desired table-top height
●Tighten screws 1well.
●Adjust the position of the pedal so that you can operate it comfortably and
tighten screw 2.
Fig. 8 - 01
87
-
007
1
1
2
2