Changing The Lower Stepping Motor - Pfaff expression 2014 Service Manual

37. Changing the lower stepping motor

Note:
The feed stepping motor is only exchanged complete.
Removal:
Remove the machine's power plug.
Remove the detachable work support.
Remove the housing according to the service manual.
Remove tension spring 3 (fig. 107).
Unscrew and remove fastening screw 4.
Remove clamping plate 21.
Turn the handwheel until the lobe of feed eccentric 5 is positioned at the rear.
Fold feed regulator 6 downwards and remove this and link 7 from the connecting bar rod to the left.
Remove slide block 8 with the spring to the right.
Unscrew and remove both screws 15 of the stepping motor.
Remove the complete stepping motor 17.
Fitting:
Insert feed stepping motor 17 complete with the bracket (fig. 107).
Insert and slightly tighten upper fastening screw 15.
Insert and slightly tighten clamp spring 137 with the lower screw 15.
Push slide block 8 with spring onto the bolt and set it in the guide slot in the correct curve radius.
Check that the slide block moves freely, but without play or binding, in the guide slot.
Push guide lever 16 complete with stepping motor 17 carefully to the left, until there is a clearance of
0.05 mm between the slide block 8 and the connecting bar 19.
Tighten screws 15 and check that the slide block moves freely, but without play.
Push link 7 complete with feed regulator 6 to the right onto the connecting bar pin.
Insert fastening screw 4 in clamping plate 21 and tighten it a little.
Shift fulcrum stud 20 laterally so that link 7 and connecting bar 19 still have a slight play and can
move freely.
Tighten screw 4.
Attach tension spring 3.
Mount the housing according to the service manual.
After a running-in time of 10 - 15 min. check the adjustment of equal forward and reverse stitch length
according to section 21 of this service manual.
Carry out an electrical safety test in accordance with VDE 0701 using testing appliance Metra-
watt 5013.
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