Selecting The Motor Pulley And The Belt; Installing The Motor; Setting The Belt - JUKI MF-7900 Instruction Manual

2. Selecting the motor pulley and the belt

Motor pulley and belt
50Hz
Pulley sze Belt sze Pulley sze Belt sze
Speed of
sttch (st/mn)
4,500 ø 00
4,800 ø 0
5,000 ø 5
5,500 ø 25
5,800 ø 35
6,000 ø 40
6,200 ø 45
6,500 ø 50
When you use a new sewing machine, use
the machine at a speed of 4,500 sti/min or
less for the first 200 hours (approximately
one month). a good result can be obtained in
terms of the durability.

3. Installing the motor

Lower
pulley
40˚
5.5 mm
10 mm
M o t o r
M type V belt
pulley

4. Setting the belt

WarNING :
When replacing the belt, be sure to turn oFF the power to the motor and ascertain that the motor has
totally stopped rotating before starting the work. there is a danger of injury since hands or clothes may
be caught in the belt.
5
60Hz
M-39 ø 85 M-38
M-40 ø 90 M-38
M-40 ø 95 M-39
M-4 ø 05 M-39
M-42 ø 0 M-40
M-42 ø 5 M-40
M-43 ø 20 M-4
M-43 ø 25 M-4
3
2
15 to 20mm
1
4
* The table shows the numbers when a 3-phase
2-pole 400 W clutch motor ( / 2 HP) s used.
* The commercally-avalable motor pulley near to
the counted value s desgnated snce the outsde
dameter of the commercally-avalable motor pulley
counts by 5 mm.
use a motor pulley which is adaptable to this
sewing machine. The sewing speed exceeds
the max. sewing speed of this sewing
machine and machine trouble will be caused
unless a motor pulley which is adaptable to
this sewing machine is used.
Use a clutch motor of 3-phase, 2-pole, 400 W (/2HP).
Use the M type V belt.
) The motor pulley shfts to the left-hand sde when
depressng the pedal. At ths tme, nstall the motor
so that the centers of motor pulley and lower pulley
algn wth each other.
* For the nstallng procedure of the motor pulley, refer
to the Instructon Manual for motor.
2) Install the motor so that the pulley rotates clockwse.
If the machine pulley rotates in the reverse
direction, nomal lubrication cannot be
performed. as a result, machine trouble will
be caused.
) Ft belt 1 to lower pulley 2 .
2) Turnng upper pulley 3 , set the other sde of the belt
to motor pulley 4 .
3) Adjust the belt tenson so that the belt sags 5 to 20
mm when the center of the belt s pressed wth an
approxmate 0N (.02 kgf) load.
4) Securely fix the belt with lock nut 5 when the belt
has been set.
If the deflection of the belt is excessive when
the sewing machine is operated, check again
the belt tension.
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