Application Of Belts And Pulleys - Mitsubishi Electric JR Series Instruction Manual

(4) Chain drive
Adjust the chain length so that a slight slackness is formed when the gears are aligned. The
shaft-to-shaft distance should be larger than the diameter of the larger gears plus the diameter of
the smaller gears.
Consult with the chain manufacturer for the max. speed and chain lubrication, etc.
(5) Coupling with internal shaft by key
If the shaft is fitted loosely in the hole, rotary eccentric load will be generated, and creep may occur
on the fitting surfaces of the motor bearing. It is recommended that the gap between the fitting
surfaces be 0.03 mm or less as a difference in diameter.
(6) Other precautions
a. The balance of the items fixed to the motor shaft such as the pulley, coupling and gears must be JIS
B 0905 (balance of rotation devices) Within Class G2.5 when measured with a balancing machine
(vibration measuring instrument). The motor will abnormally vibrate if the balance is incorrect.
(Note) 1. Rusting of the outer bearing ring and wearing of the housing is caused by repeated fine
friction of the bearing engagement section. This is caused by an unbalance.
2. Take note to the tolerable center runout of commercial flexible couplings.
b. If the pulley or coupling is hammered hard to fit it to the motor shaft, the bearing may be
damaged. When the shrinkage margin with the shaft is large, shrink-fit it. To fit the shaft end key,
use a vinyl hammer. (An iron hammer will give a high impact and may damage the bearing.)
c. If a rust preventive agent with high rust prevention ability has been applied to the motor output
shaft and attached key, remove the agent prior to use.
d. When the attached key has a shape of bilge on one side, fit the key with the bilge side in the key
seat (downward).

6. APPLICATION OF BELTS AND PULLEYS

If the selection of the belt and belt tensioning method are mistaken when coupling the motor and
partner machine with a belt, an excessive force could be applied on the shaft end and bearings, the life
may be shortened and damage could occur. Observe the following points when making the selection
and installing.
(1) The application of the motor side V-pulley and V-belt is as shown in Table 4. If the pulley diameter
is smaller or the No. of belts larger than the values given in Table 4 or if the stepped section of the
motor shaft and the rim edge of the pulley are not on the same plate, confirm that the belt load is
lower than the motor's tolerable radial load. If the belt load is larger than the motor's tolerable radial
load, reselect motor or the pulley and belt combination.
The relation of the force applied on pulley and motor shaft is as follows.
Relation of force applied on pulley diameter and shaft
..... The larger the diameter is, the smaller the force
applied on the shaft will be.
Relation of force applied on pulley width and shaft
stepped section
..... The larger the width is, the greater the force
applied on the shaft stepped section will be.
Relation of force applied on pulley axial center and shaft
stepped section
..... The greater the clearance between the center and
shaft stepped section is, the greater the force
applied on the shaft stepped section will be.
(Install so that the motor shaft stepped section and
pulley rim edge is on the same plate.) (Refer to Fig. 5.)
[Supplement] Formula for estimating axial load Fs by belts
Fs ＝ 2×N×(16×Td-Y) ×sin(φ/2)
N : Number of belts
Td : Deflection load (N/belt) (Refer to Table 4.)
Y : Coefficient according to kind of V-belt A(14.7), B(19.6), C(29.4), D(58.8), 3V(19.6),
5V(49)
φ : Contact angle (Refer to Table 3.)
Remarks 1. For more information, refer to Technical Data No.108 issued by The Japan
2. For the allowable radial load at the shaft end, refer to "Technical Information" in
Electrical Manufacturers' Association.
the general catalog.
Motor
shaft
Fig. 5 Installation of pulleys
- 5 -
V-pulley
PW
Ventilation hole
PW
t =
2
Load point