Mitsubishi Electric JR Series Instruction Manual page 9

(b) Obtain the center of t, apply a perpendicular load to the V-belt at this center point, and
obtain the deflection force Td (N) where the deflection amount  at that point is the
following value.
 = 0.016  t (mm) (Refer to Fig. 4.)
For example, the deflection amount for a distance of 1m between the belt contact would be
0.016  1000 = 16 (mm).
(c) Obtain the deflection force Td (N) for each belt, and adjust the belt tension so that the
average value enters the range of the values given in Table 4.
1. When using multiple V-belts, use a matched set that has the same belt lengths.
2. When running the motor after mounting a new belt, the belt will elongate after two to
eight hours and become loose. Thus, adjust with the retensioning deflection force (Td)
according to Table 4.
3. Always adjust the belt after it has been replaced. If an old belt is used for the
replacement, adjust with the retensioning deflection force (Td).
D
e. If the belt slackens during use, adjust the tension with the adjusting bolt on the motor's slide
base. If the flat belt slips, apply a small amount of belt wax. Do not use wax for the V-belt.
f. The pulley selection is often a problem for using the belt drive, so refer to the section "6.
APPLICATION OF BELT AND PULLEY. "
g. The deflection force Td given in Table 4 is the value for when the contact angle between the
belt and V-pulley is 140°C. If the contact angle changes, multiple the deflection force in Table 4
by the compensation coefficient K in Table 3, and obtain the deflection force for each.
Example : 0.4kW, 4-pole, standard V-belt, contact angle 180° :
Contact angle ø
K
h. When using a V-belt or V-pulley other than that shown in Table 4, the deflection force Td (N)
must be calculated separately. Refer to the catalog issued by the belt maker or the Japan
Electrical Manufacturers' Association Technical Document No. 108 "V-belt tension and
application" for the calculation method.
(3) Gear coupling
Engage the gears when the motor and partner machine shafts are parallel. Check the following
points to confirm that the gears are correctly engaged. Note that if the gear diameter is small,
bending load may be applied to the shaft.
There is a possibility of generation of high frequency vibration as large as the number of teeth of gear
× rotation speed (nZ component). Check the vibration (speed/acceleration) to confirm that it is within
the standard range. (Also in the case of use of timing belt, high frequency vibration may occur.)
a. Check the centers of both gears aligned.
b. If possible, apply a light coat of red iron oxide, and rotate the gears to confirm that the teeth are
contacted.
c. Check any abnormal noise during the rotation.
d. Check the backlash an appropriate value when the thickness is measured with a thickness
gauge.
t

d
Td
C
Deflection force Td (180°) = K  Td (140°) = 0.9  (6.9 to 7.8)
Table 3 contact angle compensation coefficient
140°
1.0
D : Large V-pulley diameter (mm)
d : Small V-pulley diameter (mm)
C : Shaft-to-shaft distance (mm)
Td : Deflection force (N/belt) (Refer to Table 4)
ø
ø : Contact angle
Fig. 4
.
. 6.2 to 9.0 (for new belt tensioning)
=
150° 160°
0.98 0.94
- 4 -
170° 180°
0.91 0.9