Singer 189 User Manual

ML189-3A

CLINTON'S

MODEL 189

UNDERBED TRIMMER

FOR

SINGER 591

SERVICE

MANUAL

40-0152-01

ML1889-25B

TABLE OF CONTENTS

THREAD TRIMMER SECTION

SECTION I - GENERAL IN FORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A P PLICATI O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TRIMMER COMPON E NTS . . . . . . . . . . . . . . . . . . . . . . . .

SECTION II - INSTALLAT ION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

SECTION III - AIR CIRCUIT OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

NEEDLE C OOLER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TRIM VALVE AND PILOT VALVE . . . . . . . . . . . . . . . . . . .

FOOTLIFT, FOLDER OPENER & THREAD BLOWER . .

1 1 1

2 2 3

SECTION IV - ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

TRIMMER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

THREAD P ULLOFF CYC L E TIME . . . . . . . . . . . . . . . . . .

TRIM CYL INDER SPEED . . . . . . . . . . . . . . . . . . . . . . . . .

NEEDLE THREAD BLO WER BLAST TIM E . . . . . . . . .

SECTION V - TROUBLE SHOO TING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

SECTION VI - PARTS DRAWINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-18

3 4 4 4

GENERAL INFORMA TION

A. INTRODUCTION

The air Operated Underbed Trimmer contains a trimming system that cuts both the needle and bobbin threads simultaneously . A movable and a stationary blade, mounted on the throat plate are used in combination to pick up and cut the threads.

Solid state electronics are used to sense the position of the needle and to trigger the trimming mechanism at the proper time as well as to control footlifting and backtacking operations.

B. APPLICATION

The underbed Trimmer/Positioner enables the operator to automatically control the position of the needle in or out of the work, thereby eliminating the need for hand positioning. In addition, the top and bottom threads are automatically cut beneath the throat plate after positioning. This eliminates the need for hand trimming.

ML1889-26

C. TRIMMER COMPONENTS

The trimmer components, which can be either pre-installed on the sewing machine head and factory tested, or field installed, include:

1. Standard Components a. Thread Cutter Assembly b. T ension Release Assembly c. Needle Thread Pulloff Assembly d. Needle Thread Blower and Needle Cooler Assembly e. Foot Lifter f. Folder Opener g. Solenoid Air V alve Control Unit

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II.

INSTALLATION

A. Install the solenoid air valve assembly under the table as shown in drawing INS-1954. B. The treadle air valve is used in place of the treadle rods for the needle cooler. Refer to

speed control installation on page 7.

C. The folder opener air valve is installed as shown in (INS-1955). This should be placed in

a position convenient to the operators right knee. D. Set the machine head in the table and install the "V" belt. E. Connect all electrical cables tot he control box. F. Connect all air lines as shown in circuit diagram drawing INS-1939-1.

Note: Do not connect the air supply at this time. G. Thread the machine and sew on material being used for the operation. H. When heeling the treadle observe the 6 o'clock positioning of the thread across the hook.

If it is not between 5 and 6 o'clock readjust as described under synchronizer timing page

11.

I. Connect the air supply then sew and operate the trimmer. Refer to section III for air

circuit operations and section IV for adjustments.

III. AIR CIRCUIT OPERA TION

A. NEEDLE COOLER

Air is distributed throughout the circuit as shown in INS-1939-2. When the treadle is

pushed forward for sewing the treadle valve is opened and air flows to the needle cooler

tube. B. TRIM VALVE AND PILOT VALVE

At the end of the sewing operation the brake is applied and the needle positioner is

activated. The needle positioner will stop with the needle thread across the hook in the 6

o'clock position. The trim solenoid valve will energize. (See INS-1939-3). The trim

cylinder operates. The pilot valve actuator is pressurized shifting the pilot valve. There is

no air flow through the pilot valve since there is no pressure at the input.

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ML1889-28

The needle is raised to the up position and the trim valve is deenergized. (See INS-1933-4). The flow control in the pilot valve actuator circuit leaks the air slowly from the actuator keeping the valve shifted. Air is applied to the IN port through the NC port, now open, to the thread pulloff cylinder, tension release cylinder and throat plate blower tube.

The pilot valve returns (INS-1939-5). Air is applied to the trim cylinder to return the blade. The rate or speed of return is controlled by the flow control which controls the air exhausting from the trim cylinder. This control is used to minimize bobbin spin.

C. FOOTLIFT, FOLDER OPENER andTHREAD BLOWER

While the treadle brake is still applied the foot lift solenoid valve will energize (see INS-1939-5). Air is applied to the foot lift cylinder and the folder opener . The folder can be operated independent of the footlifter at any time in the cycle with a knee oper ated air valve.

At the same time air is applied to the double pilot valve actuators. One actuator has a larger piston than the other. The larger piston will have more force than the smaller one at the same pressure. The air flow to the larger piston is restricted by the flow to the larger piston is restricted by the flow control When air is first applied the smaller piston will shift the valve and open the port to the shuttle valve. Air will flow to the needle thread blower. Pressure is slowly increasing in the larger piston until it overcomes the other and shuts off the air supply to the blower.

IV. ADJUSTMENTS

A. TRIMMER

1. Cutter Assembly In the cut position the cutting edge of the movable blade should pass the cutting

edge of the stationary blade about 1/16". If adjustment is required loosen the lock nuts on the cylinder shaft and adjust as required.

The pickup position on the movable blade is controlled by the stroke length of the cylinder and proper positioning of the cutting edge as above.

2. Thread Pulloff and T ension Release No adjustment is required for the Thread Pulloff and Tension Release assemblies for

trimmer operations. If check spring adjustment is required for stitch formation, remove the assembly from the machine, loosen the stud lockscrew, adjust spring tension, tighten lockscrew and replace assembly.

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ML1889-29

B. THREAD PULLOFF CYCLE TIME

The flow control in this circuit determines the time these cylinders have to complete their stroke. Too much time will show a noticeable hesitation before return of the pulloff cylinder. If the time is short the cylinder will not complete its stroke. Turning is (cw) will increase time, turning out (ccw) will decrease time.

C. TRIM CYLINDER SPEED

Turning the flow control needle in (cw) will slow down the cylinder and reduce spin. Turning out (ccw) will increase cylinder speed. If cylinder speed is too slow the presser foot will rise before the thread is cut and the operator could start removing the garment too soon. If this happens the cylinder speed should be increased and some mechanical device such as star springs used in conjunction with the flow control to reduce spin.

D. NEEDLE THREAD BLOWER BLAST TIME

The duration of this blast is controlled by the flow control mounted to the larger actuator. Turning in (cw) increases time turning out (ccw) decreases time. About one second is enough to give the operator time to remove the garment and blow the thread above the foot. Should the operator be delayed in removing the garment the thread will remain under the foot. If the foot is lowered and again raised the above sequence will repeat.

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ML1889-30A

TROUBLE SHOOTING

PROBLEM CAUSES CORRECTIVE ACTION

Defective PC Board Replace board

Needle thread not cut. Bobbin thread is cut

Both thread s not cut not picked up

Both threads picked up, not cut

Movable blade missed needle loop

Binds in trimmer linkage Locate and remove bind. A

Defective movable blade Replace Water in air lines Check filter. Remove water

Defective solenoid air valve or air cylinder

Defective PC board Replace board Binds in trimmer linkage Locate and remove bind Defective movable or

stationary blad e Stroke misadjusted failing

to reach cutting position

Check synchronizer timing to see that trimmer is fired at correct time

light bind would slow it enough to miss needle loop

from air lines Repair or replace

Replace

Readjust

Needle thread cut short Pulloff cylinder improperly

adjusted

Long tail left on top side at start of sewing

Bobbin thread is cut short

Blower not operating causing thread to be trapped under pre sser foot . Operator not removing garment fast enough

Bobbin tension too tight L oos en b obbin tension as

Bobbin thread slipped out of hook on case

Bobbin case without hook being used

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Readjust

Check blower circuit qand flow control adju stment . If blower time is short readjust flow control to increase

much as possible Run Bobbin thread through

hook Replace with correct bobbin

case

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