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Pfaff 939 U Adjustment Manual

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Enlarged version
939 U
3704
-2/02
-2/03
ADJUSTMENT MANUAL
This Adjustment Manual is valid for machines
from the following serial numbers onwards:
# 2 660 862
296-12-18 595/002
Justieranleitung engl. 01.13

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Summary of Contents for Pfaff 939 U

  • Page 1 939 U 3704 -2/02 -2/03 ADJUSTMENT MANUAL This Adjustment Manual is valid for machines from the following serial numbers onwards: # 2 660 862 296-12-18 595/002 Justieranleitung engl. 01.13...
  • Page 2 The reprinting, copying or translation of PFAFF Service Manuals, whether in whole or in part, is only permitted with our previous authorization and with written reference to the source. PFAFF Industriesysteme und Maschinen AG Hans-Geiger-Str. 12 - IG Nord D-67661 Kaiserslautern...

  • Page 3: Table Of Contents

    Multi-stitch movement (only on the PFAFF 939U) ............... 14 .05.09 Zigzag stitch movement (only on the PFAFF 3704-2/..) ............15 .05.10 Needle penetration symmetry - left, centre and right (only on the PFAFF 3704-2/..) ... 16 .05.11 Zigzag movement (only on the 939U) .................. 17 .05.12 Target positioning sensor (only on the 939U) ..............
  • Page 4 Bobbin winder ........................48 .05.43 Stitch condensation (only on the PFAFF 3704-2/02) ............49 .05.44 Switching to reverse feed (only on the PFAFF 3704-2/03) ........... 50 .05.45 Thread puller (only on the PFAFF 3704-2/02) ............... 51 Adjusting the thread trimmer -900/24 ................52 .06.01...

  • Page 5: Adjustment

    Justierung Adjustment On the PFAFF 939 U and 3704 do not use a screw clamp on the needle bar! The special coating of the needle bar could be damaged. Please observe all notes from Chapter 1 Safety of the instruction manual! In particular care must be taken to see that all protective devices are refi...

  • Page 6: Check And Adjustment Aid

    Justierung Check and adjustment aid By blocking with holes 1 - 5 the required needle bar positions can be fi xed ex- actly. Fig. 1 - 01 ● Turn the balance wheel until the needle bar has approximately reached the required posi- tion.

  • Page 7: Adjusting The Basic Machine

    Justierung Adjusting the basic machine Balancing weight .05.01 Requirement With the needle bar at bdc the largest eccentricity of the balancing weight 1 must be pointing upwards. Fig. 1 - 02 ● Bring the needle bar to b.d.c. ● Adjust the balance weight 1 (screw 2) in accordance with the requirement.

  • Page 8: Centering The Needle In The Needle Hole (In Sewing Direction)

    Justierung Centering the needle in the needle hole .05.02 (in sewing direction) Requirement With the zigzag setting at "0" and the needle position set at "middle" the needle must enter the center of the needle hole as viewed in the direction of sewing. Fig.

  • Page 9: Parallel Guiding Of The Needle Bar

    Justierung Parallel guiding of the needle bar .05.03 Requirement Guide bar 5 must be parallel to the needle bar. Fig. 1 - 04 ● Bring the needle bar to tdc (hole 2). ● Loosen screws 1,2 and nut 3. ● The largest eccentricity of pin 4 must be facing downwards. ●...

  • Page 10: Locking Lever

    Justierung Locking lever .05.04 Requirement The zigzag stitch adjustment lever 3 must be able to be locked in any position. Fig. 1 - 05 ● Loosen screw 2. ● Press locking lever 1 against the zigzag stitch adjustment lever 3. ●...

  • Page 11: Zero Stitch And Zigzag Stitch Scale

    Justierung Zero stitch and zigzag stitch scale .05.05 Requirement With the zigzag stitch set at "0": 1. the needle bar must not move laterally when the balancewheel is turned and 2. the marking "0" on scale 1 must be at marking 2. Fig.

  • Page 12: Centering The Needle In The Needle Hole (Crosswise To Sewing Direction)

    Justierung Centering the needle in the needle hole .05.06 (crosswise to sewing direction) Requirement With the zigzag stitch set at "0" and the needle position setting at "middle" the needle must enter the center of the needle hole as seen across the direction of sewing. Fig.

  • Page 13: Zigzag Stitch Width

    Justierung Zigzag stitch width .05.07 Requirement At the largest zigzag stitch setting, marking 1 must be at the largest zigzag value on scale 2. Fig. 1 - 08 ● Turn the zigzag stitch adjustment lever 3 in accordance with the requirement. ●...

  • Page 14: Multi-Stitch Movement (Only On The Pfaff 939U)

    Justierung Multi-stitch movement .05.08 (only on the PFAFF 939U) Requirement 1. When the needle, at its b.d.c., penetrates on the right-hand side, the recess 5 on the control cam 3 should be positioned horizontally towards the rear. 2. The lateral movement of the needle bar should have been completed when the needle penetrates the workpiece (carry out a check with the largest zigzag setting).

  • Page 15: Zigzag Stitch Movement (Only On The Pfaff 3704-2

    Justierung Zigzag stitch movement .05.09 (only on the PFAFF 3704-2/..) Requirement When the needle bar, on the right of its throw, is positioned at t.d.c. (adjustment hole "2"), the needle bar should not move laterally when the zigzag stitch adjustment lever is mo- ved to and fro.

  • Page 16: Needle Penetration Symmetry - Left, Centre And Right (Only On The Pfaff 3704-2

    Justierung Needle penetration symmetry - left, centre and right .05.10 (only on the PFAFF 3704-2/..) Requirement When the zigzag stitch is set at "0", the needle should penetrate in the centre of the needle hole. With the maximum zigzag stitch set, the needle should penetrate on the left and right at the same distance from the centre hole.

  • Page 17: Zigzag Movement (Only On The 939U)

    Justierung Zigzag movement .05.11 (only on the 939U) Requirement When the needle bar, moving from its right b.d.c., reaches its t.d.c. (hole 2), it should not carry out any lateral motion when the zigzag stitch width lever 4 is moved to and fro. Fig.

  • Page 18: Target Positioning Sensor (Only On The 939U)

    Justierung Target positioning sensor .05.12 (only on the 939U) Requirement There should be a clearance of 0.2 – 0.3 mm between sensor 1 and control cam 3. Fig. 1 - 13 ● Adjust sensor 1 (screws 2) in accordance with the requirement.

  • Page 19: Needle Position Adjustment Lever

    Justierung Needle position adjustment lever .05.13 Requirement The left and right throws of the needle must be the same size at the largest zigzag stitch setting and at the left or right needle position. Fig. 1 - 14 ● Loosen screws 1 and 2. ●...

  • Page 20: Adjustment Wheels For Differential Feed (Only On The Pfaff 939U)

    Justierung Adjustment wheels for differential feed .05.14 (only on the PFAFF 939U) Requirement With guide pin 3 in the middle of the connecting link and the ends of the toothed racks 4 fl ush with each other, the zero markings on the adjustment wheels 5 must be at marking 6.

  • Page 21: Zeroing The Differentiatio (Only On The Pfaff 939 U)

    Justierung Zeroing the differentiatio .05.15 (only on the PFAFF 939 U) Requirement With the largest stitch length set, the reverse feed control key 12 should be set at its highest position. In addition the stop lug 11 of clamp crank 8 should be touching the top regulating shaft.

  • Page 22: Differential Feed Synchronisation (Only On The Pfaff 3704-2

    Justierung Differential feed synchronisation .05.16 (only on the PFAFF 3704-2/..) Requirement When the stitch length is set at "1.5" and both levers 1 are in the "0" position, the two feed dogs 5 should move the same distance when the balance wheel is turned.

  • Page 23: Position Of The Stitch Length Adjustment Wheel (On The Pfaff 939 U)

    Justierung Position of the stitch length adjustment wheel .05.17 (on the PFAFF 939 U) Requirement When adjustment wheel 1 is turned as far forward as possible, the pointer 4 should be po- sitioned exactly opposite the mark "0" on scale 5.

  • Page 24: Position Of The Stitch Length Adjustment Wheel (On The Pfaff 3704-2

    Justierung Position of the stitch length adjustment wheel .05.18 (on the PFAFF 3704-2/..) Requirement When adjustment wheel 1 is turned as far forward as possible, the marking for "0" on adjustment wheel 1 and the marking on the reverse feed control should match.

  • Page 25: Zeroing The Main Feed (Rear Feed Dog) On The Pfaff 939 U

    Justierung Zeroing the main feed on the PFAFF 939 U .05.19 (rear feed dog) Requirement With the stitch length set at "0", when the balance wheel is turned, there should be no feeding motion of the rear feed dog. Fig. 1 - 20 ●...

  • Page 26: Zeroing The Main Feed (Rear Feed Dog) On The Pfaff 3704-2

    Justierung Zeroing the main feed on the PFAFF 3704-2/.. .05.20 (rear feed dog) Requirement With the stitch length set at "0", when the balance wheel is turned, there should be no feeding motion of the rear feed dog. Fig. 1 - 21 ●...

  • Page 27: Zeroing The Differential Feed (Front Feed Dog) On The Pfaff 939 U

    Justierung Zeroing the differential feed on the PFAFF 939 U .05.21 (front feed dog) Requirement With the stitch length set at "0" and the adjustment wheels set at "0", when the balance wheel is turned, there should be no feeding motion of the differential feed dog 7.

  • Page 28: Zeroing The Differential Feed (Front Feed Dog) On The Pfaff 3704-2

    Justierung Zeroing the differential feed on the PFAFF 3704-2/.. .05.22 (front feed dog) Requirement When the stitch length is set at "0" and both levers 1 set at the "0" position, the differenti- al feed dog 4 should not make any feeding movement when the balance wheel is turned.

  • Page 29: Torsion Spring Of The Reverse Feed Lever (On The Pfaff 939 U)

    Justierung Torsion spring of the reverse feed lever .05.23 (on the PFAFF 939 U) Requirement With the presser foot raised, the longest stitch length set and the adjustment wheels 4 at "0", the reverse feed lever 5 must return automatically to its uppermost point after being activated.

  • Page 30: Torsion Spring Of The Reverse Feed Lever (On The Pfaff 3704-2

    Justierung Torsion spring of the reverse feed lever .05.24 (on the PFAFF 3704-2/..) Requirement With the presser foot raised, the longest stitch length set and the adjustment lever 4 at "0", the reverse feed lever 5 must return automatically to its uppermost point after being activated.

  • Page 31: Torsion Spring Of The Differentiation Regulating Shaft (On The Pfaff 939 U)

    Justierung Torsion spring of the differentiation regulating shaft .05.25 (on the PFAFF 939 U) Requirement With the presser foot raised, the stitch length set at "0", adjustment wheel 4 at + 4.5 and adjustment wheel 5 at "0", guide pin 6 must be touching in connecting link 7.

  • Page 32: Torsion Spring Of The Differentiation Regulating Shaft (On The Pfaff 3704-2

    Justierung Torsion spring of the differentiation regulating shaft .05.26 (on the PFAFF 3704-2/..) Requirement When the presser foot is raised, the maximum stitch length set, lever 4 raised to its top position and lever 5 set at "0", the pointer 6 should be touching lever 4.

  • Page 33: Feeding Motion Of The Main And Differential Feeds

    Justierung Feeding motion of the main and differential feeds .05.27 Requirement With the maximum stitch length set and the needle bar positioned 1.0 after t.d.c. (hole 4), when the reverse stitch key is operated, there should be no feeding motion of the main and differential feed dogs.

  • Page 34: Lifting Stroke Of The Main And Differential Feed Dogs

    Justierung Lifting stroke of the main and differential feed dogs .05.28 Requirement With the stitch length set at "0" and the needle bar positioned at 0.25 after t.d.c. (hole 3), the feed dogs should be at the top of their stroke. Fig.

  • Page 35: Height Of The Main And Differential Feed Dogs

    Justierung Height of the main and differential feed dogs .05.29 Requirement With the stitch length set at "0" and the needle bar positioned at 0.25 after t.d.c. (hole 3): 1. The feed dogs should be in the centre of the needle plate cutout and be touching the feed dog height adjustment gauge over their whole length.

  • Page 36: Drive Belt In The Gearbox Housing

    Justierung Drive belt in the gearbox housing .05.30 Requirement Drive belt 4 must be tightened so that the machine runs freely and the belt sprockets do not have any noticeable play. Fig. 1 - 31 ● Adjust eccentric bearing bush 1 (screw 2) in accordance with the requirement and so that drive belt 4 is in the centre of bobbin opener drive wheel 3.

  • Page 37: Hook Bearing Bracket

    Justierung Hook bearing bracket .05.31 Requirement The hook shaft must be touching the hook bearing bracket adjustment gauge 1 at the top and the side. 438 - 439 Fig. 1 - 32 ● Loosen screw 3. ● Swing the bobbin case opener to the right and remove the hook. ●...

  • Page 38: Hook Lubrication

    Justierung Hook lubrication .05.32 Requirement When the machine is running at full speed, after about 10 seconds a fi ne oil streak should be visible on a strip of paper held over the needle plate cutout. Fig. 1 - 33 ●...

  • Page 39: Pre-Adjusting The Needle Height

    Justierung Pre-adjusting the needle height .05.33 Requirement With the needle bar at tdc (hole 2) the distance between the point of the needle and the needle plate must be 19 mm. 19 mm Fig. 1 - 34 ● Without turning it, adjust the needle bar (screws 1) in accordance with the requirement.

  • Page 40: Needle Rise, Hook-To-Needle Clearance And Bobbin Case Positioning-Fi Nger

    Justierung Needle rise, hook-to-needle clearance and bobbin case positioning-fi nger .05.34 Requirement 1. With the needle position set at "middle", the zigzag stitch setting at "0" and the needle bar position 2.0 past bdc (hole 1) the hook point must be in the middle of the needle and the distance between the needle and the hook point must be 0.05 - 0.1 mm.

  • Page 41: Final Adjustment Of The Needle Height

    Justierung Final adjustment of the needle height .05.35 Requirement With the zigzag stitch set at "0", the needle position set at "left" and the hook point in the middle of the needle, the top edge of the needle eye must be 0.5 mm underneath the hook point.

  • Page 42: Bobbin Case Opener Position

    Justierung Bobbin case opener position .05.36 Requirement 1. There must be a clearance of 0.5 mm between the top edge of the bobbin case opener and the inner edge of the bottom section of the bobbin case. 2. Between the bobbin case opener fi nger and the bottom section of the bobbin case opener there must be a clearance of 0.8 mm.

  • Page 43: Bobbin Case Opener Motion

    Justierung Bobbin case opener motion .05.37 Requirement With the needle bar 2.0 past bdc (hole 1) the bobbin case opener 3 must be at its right point of reversal. Fig. 1 - 38 ● Adjust eccentric 1 (screws 2) in accordance with the requirement.

  • Page 44: Presser Foot To Needle Plate Clearance / Presser Foot Pressure

    Justierung Presser foot to needle plate clearance / Presser foot pressure .05.38 Requirement 1. When the hand lever is raised, the needle should penetrate exactly in the "needle hole centre" of the presser foot and the presser foot to needle plate clearance should be 5 mm. 2.

  • Page 45: Thread Diverter Pin

    Justierung Thread diverter pin .05.39 Requirement With the needle bar at bdc the top edge of the thread guide hole must be at the same height as the bottom edge of the thread diverter. Fig. 1 - 40 ● Move thread diverter 1 (screw 2) in accordance with the requirement, ensuring that it remains parallel to the base plate.

  • Page 46: Limiting The Knee Lever Stroke

    Justierung Limiting the knee lever stroke .05.40 Requirement When the knee lever is pressed the hand lever must drop automatically and the presser foot must be just over 7 mm above the needle plate. Fig. 1 - 41 ● Place the feed dog gauge under the presser foot with its recess facing downwards. ●...

  • Page 47: Knee Lever Play

    Justierung Knee lever play .05.41 Requirement When lightly pressing the knee lever there should be a noticeable play between nut 1 and fork 3. Fig. 1 - 42 ● Adjust nut 1 (lock nut 2) in accordance with the requirement.

  • Page 48: Bobbin Winder

    Justierung Bobbin winder .05.42 Requirement 1. With the bobbin winder engaged the bobbin winder spindle must be turned reliably, but friction wheel 5 must not touch drive wheel 1 when the bobbin winder is switched off. 2. The bobbin winder must disengage automatically when the thread is approx. 1 mm from the edge of the bobbin.

  • Page 49: Stitch Condensation (Only On The Pfaff 3704-2/02)

    Justierung Stitch condensation .05.43 (only on the PFAFF 3704-2/02) Requirement When the stitch condensation function is switched on, the feed stroke of the main and dif- ferential feed dog should be 0.2 – 0.3 mm. Fig. 1 - 44 ● Adjust crank 1 (screw 2) and crank 3 (screw 4) in accordance with the requirement.

  • Page 50: Switching To Reverse Feed (Only On The Pfaff 3704-2/03)

    Justierung Switching to reverse feed .05.44 (only on the PFAFF 3704-2/03) Requirement When the reverse feed function is switched on, the actual length of the reverse stitches should correspond to the set stitch length. Fig. 1 - 45 ● Adjust crank 1 (screw 2) and crank 3 (screw 4) in accordance with the requirement.

  • Page 51: Thread Puller (Only On The Pfaff 3704-2/02)

    Justierung Thread puller .05.45 (only on the PFAFF 3704-2/02) Requirement The thread puller should 1. draw so much thread that a secure seam start is guaranteed at all times and 2. remain in its end front position until the thread trimming operation is fi nished.

  • Page 52: Adjusting The Thread Trimmer -900/24

    Justierung Adjusting the thread trimmer -900/24 Axial position of the control cam .06.01 Requirement 1. Roller 5 should be at a distance of 0.3 mm from the control cam 1. 2. Adjustment ring 3 should be touching the control cam 1. 0,3 mm Fig.

  • Page 53: Preliminary Adjustment Of The Control Cam

    Justierung Preliminary adjustment of the control cam .06.02 Requirement 1. In the needle rise position (hole 1) the roller lever 4 should lock into the corresponding groove of the control cam. 2. The control cam 1 should be touching adjustment ring 3. Fig.

  • Page 54: Position Of The Thread Catcher And Cutting Test

    Justierung Position of the thread catcher and cutting test .06.03 Requirement When the thread trimmer is in its neutral position, the edge of thread catcher 6 should be fl ush with the edge of the mounting plate 4. Fig. 1 - 49 ●...

  • Page 55: Readjustment Of The Control Cam

    Justierung Readjustment of the control cam .06.04 Requirement 1. When the end of the hook guard 3 is level with of the right edge of the bobbin case position fi nger 4, the thread catcher 5 should begin moving forwards. 2.

  • Page 56: Needle Thread Tension Release

    Justierung Needle thread tension release .06.05 Requirement 1. When solenoids 3 are activated, the tensions disks 4 should be at least 0.5 mm apart. 2. When the thread trimmer is in its neutral position and the sewing foot is positioned on the needle plate, the tension should be fully effective.

  • Page 57: Switch Diagrams

    91-191 281-95 Pneumatics-switch diagram Version 01.10.04 Switch diagrams Pneumatics-switch diagram (for the PFAFF 3704)
  • Page 58 Circuit diagrams Referenc list for circuit diagrams Controller P40 ED Control panel S3 Oberteilerkennung (OTE) Initiator zig-zag stitch control (only on the PFAFF 939 U) Sewing lamp LED Stitch counter Main switch Pedal set value transmitter Start inhibitor key (only on the PFAFF 939 U)
  • Page 59 Circuit diagrams 91-191 477-95 PFAFF 939 U Part 1 Version 05.11.03...
  • Page 60 Circuit diagrams 91-191 477-95 PFAFF 939 U Version 05.11.03 Part 2...
  • Page 61 Circuit diagrams 91-191 477-95 PFAFF 939 U Part 3 Version 05.11.03...
  • Page 62 Circuit diagrams 91-191 487-95 PFAFF 3704 Version 03.09.04 Part 1...
  • Page 63 Circuit diagrams 91-191 487-95 PFAFF 3704 Part 2 Version 03.09.04...
  • Page 64 Circuit diagrams 91-191 487-95 PFAFF 3704 Version 03.09.04 Part 3...
  • Page 65 Note...
  • Page 66 PFAFF Industriesysteme und Maschinen AG Hans-Geiger-Str. 12 - IG Nord D-67661 Kaiserslautern Phone: +49 - 6301 3205 - 0 Fax: +49 - 6301 3205 1386 E-mail: info@pfaff-industrial.com Printed in Germany...

This manual is also suitable for:

3704-2/023704-2/03

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