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 Tension 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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