3. Head of the sewing machine .............................................................................................................................................. 2
3. 1 Hook and hook box .................................................................................................................................................................. 2
3.1.1 Description
3.1.2 Height setting of the hook
3.1.3 Setting the distance of the hook from the needle
3.1.4 Angular setting of the hook (timing)
3.1.5 Protection of the needle and of the hook point
3.1.6 Setting of the bobbin case opener
3.1.7 Setting the regulation of the hook lubrication
3.1.8 Replacement of the hook
3.1.9 Setting the gear
3.1.10 Dismantling of the hook box
3.2Needle and thread mechanism ................................................................................................................................. 5
3.2.1 Description
3.2.2 To check the handwheel angular adjustment
3.2.3 Height setting of the needle bar
3.2.4 Angular setting of the pin of the thread mechanism
3.2.5 Side setting of the needle bar holder
3.2.6 Setting the needle (the needle bar holder) in the direction of sewing (fine setting)
3.3.2 Mounting and removing the throat plate and its insert
3.3.3 Setting the throat plate and its insert
3.4Thread tensioners and limiter ................................................................................................................................. 8
3.4.1 Description
3.4.2 Setting the tension of main and auxiliary tensioners
3.4.3 Setting the tensioning mechanism of the main tensioner
3.4.4 Setting the adapting spring
3.4.5 Setting the thread limiter
3.5Feeding mechanism of the needle feed and of the lower feed wheel ....................................................................10
3.5.1 Description
3.5.2 Stitch length mechanism
3.5.2.1Setting the upper eccentric
3.5.2.2Setting the prop
3.5.2.3 a Forward and rearward stitch length distribution (rough)
3.5.2.3 b Forward and rearward stitch length distribution (fine)
3.5.2.4Setting of the control knob (including the stitch length limitation)
3.5.3 Setting the needle feed (rough)
3.5.4 Lower feed wheel
3.5.4.1Feeding clutches
3.5.4.1.1 Description
3.5.4.1.2 Setting the lever of the second step of feeding(angle, position)
3.5.4.1.3 Setting of the lower eccentric
3.5.4.1.4 Setting the engagement and disengagement of the clutches
3.5.4.2Wheel feeder and its post
3.5.4.2.1 Height setting of the feeder
3.5.4.2.2 Replacement of the feeder
3.5.5 Setting the top roller (pressing force, height)
3.6Feeding mechanism of the top roller ....................................................................................................................15
3.6.1 Description
3.6.2 Side setting of the indented lower pulley
3.6.3 Side setting of the indented upper pulley
3.6.4 Setting the tensioning roller
3.6.5 Replacement of the indented belt
3.6.6 Setting the feeding difference
3.6.7 Replacement of the friction wheels of the drive conversion unit
3.6.8 Top roller
3.6.8.1 Selection of the top roller diameter
3.6.8.2 Forward, rearward and side setting
3.6.8.3 Setting the gear clearance
3.6.8.4 Replacement of the top roller
3.7Setting the presser foot lift .................................................................................................................................... 19
3.10 Indented belt transmission ................................................................................................................................... 21
3.10.1 Setting the tensioning roller of the indented belt
3.10.2 Replacing the indented belt
3.11 V-belt, motor - head .............................................................................................................................................. 22
4.7 Setting the retaining spring of the hook thread
4.8 Setting switching of the electromagnets
5. Lifting the top roller by electromagnet ........................................................................................................................... 26
5.1 Description
5.2 Setting the electromagnet pin
5.3 Setting the electromagnet current
5.4 Assembly of the top roller lifting electromagnet
6. Backtacking using electromagnet .................................................................................................................................... 27
6.1 Description
6.2 Electromagnet height setting
6.3 Setting the position of push-buttons
6.4 Change of the function of push-buttons
7. Connecting the electric elements on the machine head ................................................................................................ 28
8. Drive, control panel, position sensor ........................................................................................................................... 28
10. Maintenance (table of operations) ................................................................................................................................. 29
11. Setting the machine according to the sewing category .................................................................................................. 29
11.1 Introduction
11.2 Table of setting the machine according to the sewing category
1.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 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, top roller, needle plate, feed dog and bobbin) when treading, 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 the machine must be disconnected from the compressed air supply system.
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 directiv es.
It is absolutely necessary to respect the safety instructions marked by these signs.
Danger of bodily injuries !
Please note also the general safety instructions.
IMPORTANT WARNING
In spite of all safety measures made on the machines, inappropriate actions of the operator may lead to dangerous situations. In industrial
sewing machines Minerva, attention should be paid to the following still remaining possible sources of injury:
1. Moving sewing needle
- risk of injury when sewing with raised pressure foot or top roller, because the finger guard is then positioned too high.
2. Moving thread take-up lever
- risk of injury when inadvertently or intentionally inserting the finger(s) between the thread take-up lever and its guard.
3. Moving pressure member
- risk of injury when holding sewn work in immediate vicinity of the pressure member and beginning to insert under the pressure
member a considerably thicker sewn work portion,
- risk of injury when sinking the pressure member.
4. When switched off, the clutch motor slows down by inertia but would be reactivated by an accidental treading down of the
motor treadle. To avoid such risk, it is advised to hold the handwheel by hand and slightly to depress the motor treadle.
2.Introduction
This service book contains instruction for regulating the mechanisms of the sewing machine head.
The instructions for use and for putting the machine into operation and for the control of the stopmotor are not included in this service
book, but they are supplied as separate publications.
This service book is universal for all subclasses of the machine - it contains setting procedures for all elements which may be placed on
the machine of the given class. When the supplied subclass of this machine does not include some element, then it is possible to leave out
the respective parts of the instructions. The optional equipments of the machine and the respective configurations of the subclasses of
the machine are given in the operating instructions.
This sewing machine disposes of a large extent of its use. The machine should be set with respect to the parameters of the sewn material,
the sewing thread etc. The setting for the individual categories is given in the chapter 11.2.
For setting the machine, simple setting aids are used which are included in the accessory of the machine. Besides these aids, universal
measuring devices are used, such as slide calliper, feeler gauges and dynamometer for measuring the thread tension.
1
10
15
5
14
12
3. Head of the sewing machine
8
7
6
16
1
9
14
13
2
4
3
11
3.1 Hook and the hook box
3.1.1 Description
The hook (1) is mounted on the shaft (2) and is driven by the gear
(3) from the shaft (4).
The shaft of the hook (2) is mounted on the top in a sliding bearing
and, on the bottom, in a needle bearing.
The hook is provided with a lever (6) which is tilted when removing
the bobbin (7). The protecting sheet (8) protects against the
collision of the needle with the hook point. The bobbin case opener
(9) is driven by the eccentric (10) on the shaft (2).
The lubricating tube (11), on which a lubricating wick is fastened
in the tube (12), feeds oil for lubricating the sliding bearing (5) of
the eccentric (10) and the hook path.
The screws (13) serve for taking up the clearance of the gear. The
screws (14) fasten the hook box to the bedplate.
The lubricating felt (15) is connected by the wick (16) with the
main lubricating system and serves for lubricating the gear (3).
2
1
7
max. 0,1
A
3.1.2 Height setting of the hook
The designated distance A should be 6.1 mm.
1
4
- Remove the slide plate (1).
- Loosen both screws (2).
- By turning the screws (3 and 4), set the required distanceA.
3
5
2
After having set it, tighten carefully the screws.
- By axial shifting of the gear wheel (5), set the axial clearance
in such a way that this clearance is the least possible, but
sufficient for turning easily the hook.
- Tighten carefully the screws (2). Caution ! One of these
screws must bear on the flat of the shaft 6).
Caution! Danger of injury!
Switch off the main switch ! Before starting the setting
operation, wait until the motor stops!
6
3.1.3 Setting the distance of the hook from
the needle
The hook point (1) is set up to the maximum distance of 0.1
mm from the bottom of the needle recess (2). For the sewing
categories 1 and 2, the needle size 100 is set, for the sewing
categories 3 and 4, it is the needle size 160.
Caution! Danger of injury!
Switch off the main switch ! Before starting the setting
operation, wait until the motor stops!
4
5
6
- Shift the plate (3).
- Loosen only one screw (4).
- Loosen the screws (5) and tighten them only slightly.
- Shift the hook box (6) at the determined distance between
the needle and the hook point.
- Tighten the screw (4).
- Tighten duly the screws (5).
- Check up the setting with magnifying glass and proceed to
the eventual correction of setting.
4
5
3
Caution!
When changing substantially the sewing category, the protecting sheet of the hook (7) should be
set up.
2
3.1.4Angular setting of the hook (timing)
2
1
57
3
o
205
4
6
The hook is to be angularly set in such a way that the hook
point (1) is opposite the needle at the moment, when the
needle shifts by 2.5 mm from its bottom dead center. This
corresponds to the 2O5° on the scale of the handwheel (3).
Caution! Danger of injury!
Switch off the main switch! Before starting the setting
operation, wait until the motor stops!
- Remove the throat plate.
- Turn the handwheel (3) to the 2O5° and fix it with the screw
(4) which is component part ot the accessory of the machine
(tighten it carefully).
- Loosen the screws (5) of wheel (6).
- Turn the hook into the required position.
- Set the gearing of the wheel (6) at the centre of the wheel
(7).
- Tighten to the maximum the screws (5).
3.1.5 Protection of the needle and of the hook point
The protecting sheet (1) is to be set up in such a way that the
clearance between the protecting sheet and the needle (2) is the
3
least possible.
Caution ! Danger of injury!
Switch off the main switch! Before starting the setting
operation, wait until the motor stops!
- Remove the throat plate and the movable trimming knife.
- Unscrew the screw (3).
2
5
1
- Put the screwdriver into the hole of the screw (3) and, using the
regulating screw, set up the required clearance between the
needle (2) and the protecting sheet (1). When turning to the
right, the protecting sheet shifts out from the groowe and inversely.
- Check up the protecting effect in pushing against the needle in
the sense of the arrow (5). The hook point must not catch the
needle. If so, set up the protecting effect, correct eventually the
setting of the distance of the hook point from the needle according to the paragraph 3.1.3.
- Screw in the screw (3).
3.1.6 Setting of the bobbin case opener
6
7
3
4
The bobbin case opener (1) is to be set in such a way that, at the
moment when the opener is in its dead centre, there would be a
clearance A between the opener (1) and the projection (2),
whereas the finger (3) bears on the projection (4), A = 0.7 mm
for the sewing category 1 and 2, A = 0.3 mm for the sewing
category 3 and 4.
Caution ! Danger of injury!
Switch off the main switch! Before starting the setting
operation, wait until the motor stops!
1
2
A
o
295
- Remove the slide plate.
- On the handwheel (5), set the angle of 295° (the hook is in
its dead centre).
- Loosen the screw (6).
- Turn the eccentric (7) in such a way that the required clearance
between the elements (1) and (2) is attained.
- Tighten duly the screw (6).
5
3
0,4
3
546
7
11
10
1
1
2
8
o
15
9
3.1.7 Setting the regulation of the hook lubrication
By turning the lubricating tube (1) in the sense of the arrow
(2), the size of the contacting surface between the wick (3)
and the felt insert (4) is regulated. In this way, the speed of the
capillary lift of oil into the felt insert (5) is influenced, from
which oil is wiped on the surface (6) and is driven by centrifugal
force into the hook path (7).
Setting of full lubrication
- Turn the screw (8) into the position (9).
Setting of limited lubrication
- Turn the screw (8) into the position (10).
After having ended the regulation, set the height of the lubricating
tube (1) at 0.4 mm from the eccentric (11).
3.1.8 Replacement of the hook
1
2
3
4
5
- Remove the throat plate and the trimming knife.
- Unscrew the screws (1) and remove the gib (2).
- After having suitably turned a bit the hook, remove the bobbin
case (3).
- Unscrew thorougly the screw (4).
- Remove the body of the hook (5) upwards.
- When mounting, the procedure is inverse.
Caution! Danger of injury!
Switch off the main switch ! Before starting the setting
operation, weit until the motor stops!
3.1.9 Setting the gear
The mutual angular orientation of the gear wheel (1) relative to
the gear wheel (2) should ensure the accessibility of the screw (5)
51
910
4
2
3
9
10
8
6
o
205
at the moment when the hook point comes to lie opposite the
needle (4). The wheel (2) is to be set with its gear rim symmetrically
to the centre of the gear wheel (1). The clearance between the
gear wheels is to be the least possible.
Caution ! Danger of injury!
Switch off the main switch! Before starting the setting
operation, wait until the motor stops!
- Set the angle of 2O5° on the handwheel (6) and lock it with the
screw (7).
- Remove box of the hook (8), according to the paragraph
3.1.10, the hook point (3) is to be turned a bit according to
the illustration.
- Turn the gear wheel (2) into the suitable position and insert
the box of the hook into the machine. Check up, whether
the screw (5) is acces-sible and, if not, repeat the procedure.
- Set the the distance of the hook from the needle according
to the paragraph 3.1.3.
- Set the precise angular displacement of the hook according to
the paragraph 3.1.4.
- The screws (10) tighten slightly.
- Set the clearence in the gear in turning the screws (9). Check
up, whether the gear has a clearance during the whole revolution
of the hook. Turn the handwheel step by step by 15° and, with
each step, grasp the hook and try, if there is an angular dead
travel. Tighten carefully the screws (9).
- Tighten duly the screws (10) and try anew the clearance of the
gear.
7
4
3.1.10 Dismantling of the hook box
When dismantling the box (1), the supplies of lubricating oil
are to be disconnected first, the fastening screws unscrewed
2
3
1
5
6
4
5
6
and, thereafter, the post is removed.
Caution ! Danger of injury!
Switch off the main switch! Before starting the setting
operation, wait until the motor stops!
- Disconnect the lubricating tubes with the wicks (2) and (3)
from the lubricating box (4).
- Loosen only one screw (5).
- Unscrew the screws (6).
- Shift the hook box in the sense of the arrow and remove it
out from the machine.
- When mounting it, proceed inversely. Make sure that the
wicks in the tubes (2) and (3) are in contact with the other
wicks leading oil into the box (4).
12
1
10
11
2
3
3
8
7
2
13
1
9
4
6
3.2Needle and thread mechanism
3.2.1 Description
The take-up lever (1) is mounted in ball bearings, both at the spot
of its suspending on the connecting rod (2) and in the mounting
on the loop (12). The take-up lever is of aluminum and is provided
with a stuck-in eye for two threads. The connecting rod (2) is
mounted on the eccentric pin (3). The needle bar holder (4) is
mounted through the pin (5) in a rotating way in the arm (6).
In its top part, the holder is guided by the guide pin (7). The
movement for the needle feed is given to it by the connecting
rod (8) driven by the feeding shaft (9). The connecting rod (8)
is mounted by eccentric pin (13) with needle bar holder (4).
The connecting rod (10) of the needle bar (11) on the loop (12) is
mounted in a ball bearing and it is slidingly mounted on the needle
bar carrier. The mechanism is lubricated by means of a centralwick lubricating system.
5
3.2.2 To check the handwheel angular adjustment
The handwheel (5) must be situated in its precise position
relative to the needle and thread mechanism. This position is
given by a pin (2), which locks the connecting rod of the
needle rod (1) through a hole in the arm (3). In this position,
the indicator (6) of the handwheel must show O. The position
is fixed by the handwheel screw (4) contacting a small flat
surface provided on the upper shaft.
The correct adjustment of the angular position has been carried out at the producers.
5
4
o
0
Caution ! Danger of injury!
Switch off the main switch! Before starting the setting
operation, wait until the motor stops!
6
5
3.2.3 Height setting of the needle bar
1
1
At the moment, when the hook point passes around the needle,
the upper edge of the needle eye must be about 1 mm below
the hook point. In an opposite case, it is necessary to set the
height of the needle bar as follows:
Caution ! Danger of injury!
Switch off the main switch! Before starting the
setting operation, wait until the motor stops!
- Remove the front guard.
- Loosen the screw (1) of the needle bar carrier
- Set the correct height of the needle bar and tighten anew the
screw (1).
Caution !
An incorrect setting of the needle bar height may
cause the striking of the hook point against the needle.
1
34
3.2.4 Side setting of the needle bar holder
In the correct position of the needle bar holder, the distance
A between the needle axis on the left side and the axis of the
aperture in the throat plate is 0,1 mm.
Caution! Danger of injury!
Switch off the main switch! Before starting the setting
operation, wait until the motor stops!
- Loosen the screw (1) of the pin (2).
- Loosen the screw (3) of the guide pin (4).
- In shifting the pin (2) set the needle bar holder on the measure
A = 0.1 mm /at the same time the pin (4) shifts/.
- The guide pin (4) is to be set in such a way that the needle
bar holder moves easily.
- Tighten the screws (1 and 3).
A
2
3.2.5 Setting the needle (the needle bar holder)
in the direction of sewing (fine setting)
244
1
o
When shifting out the needle from the throat plate insert,
5
at the moment, when the needle eye is at the level of the top
surface of the throat plate insert, the distance between
3
the needle and the wall of the throat plate insert must be A =
0.2 mm.
2
- Shift the insert (4) up to the stop in the sense of the arrow.
- Set the maximum allowed stitch length.
4
A
- Set the handwheel to the angle of 244°.
- Loosen the screw (3) of the eccentric of the needle bar
holder.
- By turning the eccentric (6), set the required distance A" =
0.2 mm.
- Tighten up the screw (3) and check up the setting.
Caution ! Danger of injury!
Switch off the main switch! Before starting the
setting operation, wait until the motor stops!
Caution!
A faulty setting may cause bending or breaking of
needles against the throat plate insert.
6
244
1
o
5
3
- Shift the insert (4) up to the stop in the sense of the arrow.
- Set the maximum allowed stitch length.
2
- Set the handwheel to the angle of 244°.
- Loosen the screw (3) of the eccentric of the needle bar
holder.
- By turning the eccentric (6), set the required distance A" =
0.2 mm.
- Tighten up the screw (3) and check up the setting.
4
Caution ! Danger of injury!
Switch off the main switch! Before starting the
setting operation, wait until the motor stops!
Caution!
A faulty setting may cause bending or breaking of
needles against the throat plate insert.
A
3.3 Throat plate
3.3.1 Description
The throat plate (1) is universal for all categories of sewing. In
2
1
4
3
2
the throat plate there is mounted an exchangeable insert (2).
The machine is supplied with several types of inserts differing
in the width of their needle aperture (3), see tab. in the par.
11.2).
For ensuring a good function of the thread trimming device,
the insert can be set in various positions in the sense of arrows
in such a way that the rear edge of the hole in the throat plate
(4) prevents unthreading the thread from the sewn material
when forming the first stitches at the beginning of the seam.
3.3.2 Mounting and removing the throat plate and
6
When mounting the throat plate (1), the finger (2) must engage
into the recess (3). To remove the throat plate insert (4), screw
out the screw (5), take out the washer (7), loosen the screw
1
8
9
5
7
4
2
3
(8), and remove the inlay (4) by oblique upward movement
shown by the arrow.
- Turn the finger (2) in the sense towards the throat plate (1).
- Mount the throat plate (1).
- Screw in the screws (6).
- Slide in the insert under the washer (9) in the oblique rear-
- Mount the insert (7) and screw in the screw (5).
- Tighten the screw (8).
- When removing the insert, proceed in an inverse sequence.
its insert
Caution! Danger of injury!
Switch off the main switch! Before starting the
setting operation, wait until the motor stops!
ward sense (4).
3.3.3 Setting the throat plate and its insert
The insert of the throat plate should be set in the machines
with the trimming device in such a way that the edge (1) is at
the distance A = 1 to 2 mm before the spot of interlacing of
the threads (2). For the stitches up to the length of 2/3 of the
maximum length, the insert is to be set in its extreme front
position in the sense of the arrow. For long stitches, it should
3
1
2
3
A
be in its extreme rear position, against the sense of the arrow.
With the machines without the trimming device, the insert is
in its extreme rear position.
Caution! Danger of injury!
Switch off the main switch! Before starting the
setting operation, wait until the motor stops!
- Loosen the screws (3).
- By applying a heavy pressure of the screwdriver, shift the
insert in its required position.
- Tighten the screws (3).
7
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