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1. Remove: Mains lead - Sewing foot - Machine base - Needle plate.

2. Make sure that there is no axial play on chain looper shaft "a". If necessary, adjust with

stop collar inside shaft "g" in Fig.7 on page 12c.

3. Angular position of chain looper: Insert a new needle (Nm 90) in "L2". Check height and

orientation of needle bar on page 6. Bring chain looper to its extreme right swing position.

Check distance from point of chain looper to chain needle wi th thickness of gauge. If

necessary, loosen screw "c" just enough to adjust the chain looper arm "d" angularly to

obtain a clearnace of 1.5 to 1.8mm. Then tighten screw "c".(Fig.1)

Note: At this step, an easy check of the chain looper timing can be done as follows:

Chain looper motion right to left and the needle bar stroke should start at the same time.

Turn the handwheel towards you, bring the chain looper eye from right to left motion

behind the cover hem needle eye "L0". Check if eye of chain looper matches with eye

of needle (eye to eye).(Fig.2) If not, recheck all the above adjustments and adjust

timing stroke with eccentric "5". See page 4a & 4b for the position of eccentric. The

eccentric "5" is used for both chain and lower looper timing. When adjus ting this

timing, make sure that you also check the adjustment of lower looper stroke. See page

4. Clearance of chain looper: Bring point of looper - from right to left - behind the cover hem

needle "L2", and check if clearance is less than 0.05~0.1mm. Then bring tip of looper

behind the cover hem needle "L0", and check if clearance is less than 0.05~0.1mm.(Fig.3)

5. Clearance of chain needle(s) guard: Bring needle bar to i ts lowest position, turn the

handwheel toward you and make sure that the clearance between both chain needle guard

and needles is less than 0.05mm. If necessary, adjust clearance with screw "e".(Fig.4)

Make sure that the gap between chain needle guard and chain looper is set at 1.0mm.

(Fig.5)

Note: Make sure that the chain needle"L0" is correctly positioned behind the chain looper

in its motion left to right. The (L0) needle tip (motion down) should be positioned at

the beginning of the chain looper hump (back of chain looper). See chain looper

orbital motion on Fig.3.

12b

CHAIN LOOPER : ANGULAR POSITION - CLEARANCE - ORBITAL

TIMING - CLEARANCE OF CHAIN NEEDLES GUARD

Pfaff 4874 User Manual

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