Belt 2 runs over pulleys 4 and 5 which rotate about axes A and B. Links 6 and 7 turn about fixed axes C and D. Belt 2 is tensioned by screw device 8 with elastic element a. Disk 1 rotates about axis C of link 6. Attached to disk 1 is unbalanced mass m. When disk 1 rotates, belt 2 being tested is subjected to a pulsating load due to the action of unbalanced mass m and spring 3. Screw device 9 regulates the tension of spring 3.
$1972$FL,M$