Brother LH4-B800E Service Manual download pdf (Page 72)

LH4-B800E

3 - 17

3. ASSEMBLY

Install the two retaining rings q to the upper shaft w. Press-fit the ball bearing e as far as the retaining rings q.

(Upper shaft assembly r)

Place the timing pulley U assembly t, timing belt y, bobbin winder pulley u and set screw collar assembly i onto

the upper shaft assembly r. While pushing the timing pulley U assembly t against the retaining rings q, secure it by

tightening the set screw o. While pushing the bobbin winder pulley u against the timing pulley U assembly t, secure

it by tightening the two set screws !0.

Install the thread take-up crank !1 to the upper shaft assembly r with the screw !2 and the set screw !3.

Secure the set screw collar assembly i to the upper shaft assembly r using the thread take-up crank !1 and the two

set screws !4 so that there is no play.

Provisionally install the tension pulley assembly !5 with the two bolts !6 and the two plain washers !7. Set the phase

between the upper shaft and the lower shaft so that the mating mark (A) on the lower shaft timing pulley !8 is facing

straight down when the upper shaft assembly r is at the needle up stop position. While pushing the tension pulley

assembly !5 with a force of 100 N, secure it by tightening the two bolts !6.

Install the synchronizer assembly H80 !9 to the arm with the screw @0.

Install the pulley assembly @1 with the screw @2 so that the screw stop is at the front, and so that the clearance

between it and the synchronizer assembly H80 !9 is 0.5 mm.

3-9. Upper shaft and tension pulley mechanism

Upper shaft pulley

mating mark

100 N

0.5 mm

(Screw stop side)

(A)

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Brother LH4-B800E Service Manual Page 72