Festo Belt Drives 2, Industrial Maintenance

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Job Sheet 3 – Variable-Speed Belt Drives
© Festo Didactic 54977-3C
51
41. Measure the speed of the driven pulley (
𝑛𝑛
2
) using the photo-reflective
tachometer.
Driven pulley speed (
𝑛𝑛
2
) : ____________
Driven pulley speed (
𝑛𝑛
2
): about
289 rpm
42. Stop the motor and turn off the system.
43.
Remove the lockout device from the padlock eyes and open the safety
guard.
Wait for the motor to completely stop before removing the lockout device and
opening the safety guard.
44. Perform the Lockout/Tagout procedure.
a
Refer to Appendix B if necessary.
45. Using your measured speed values, calculate the speed ratio
�
𝑛𝑛
1
𝑛𝑛
2
�
.
Speed ratio: ____________
Speed ratio: approximately 0.7
Modification of the speed ratio
You will set the variable-pitch pulley to the open position to modify the speed
ratio.
46. Make sure there is no tension on the belt.
47. Loosen the pillow block bearings screws and move the pillow block bearings
closer to the motor mounting base.
48. Perform the following steps to adjust the variable-pitch pulley to the opened
position:
 Remove the part of the belt wrapped around the variable-pitch pulley.
 Loosen the setscrew used to lock the threaded hub into position.
 Hold the variable-pitch pulley with one hand and turn the mobile flange
counterclockwise six turns.
 Align the setscrew with the flat surface of the pulley threaded hub.
 Tighten the setscrew on the flat surface of the threaded hub.
 Wrap the A48 V-belt around the variable-pitch pulley.