How to Calculate the Number of Coils per Inch of the Roving Bobbin

Last Updated on 03/03/2021

Experiment name:
Calculation of no of coils per inch of the roving bobbin.


  1. To know the necessary specification of roving bobbin for calculation.
  2. To know how to calculate the coils/inch of roving bobbin.


We know, coils per minute = Bobbin speed – Spindle speed

Therefore, coils per inch = (Coils per minute / Rate of lift in inches per minute)

Again, rate of lift = RPM of lifter shaft wheel x Teeth of lifter wheel x pitch of the lifter wheel

Rpm of lifter shaft wheel = Motor rpm x (Driver/Driven)

Machine specification:

  1. Rpm of motor pulley = 960
  2. Motor pulley diameter = 5″
  3. Machine pulley diameter = 7″
  4. Cradle wheel = 40T
  5. Cradle carrier wheel = 55 T
  6. No of teeth in TCP = 28T
  7. No of teeth in TCCP = 30T
  8. Diameter of top cone drum = 6.5″
  9. Diameter of bottom cone drum = 3.87″
  10. Bottom cone drum change wheel = 18T
  11. No of teeth of fender wheel = 68T
  12. No of teeth of fender shaft wheel = 30T
  13. Fender swivel bracket carrier wheel = 36T
  14. Top lifter change wheel = 18T
  15. Wheel on stud bevel = 44T
  16. Stud bevel wheel = 22T
  17. Double upright bevel wheel = 22T
  18. Double upright bevel wheel = 18T
  19. Reversing bevel = 70T
  20. Reversing bevel = 70T
  21. Bobbin lifter change pinion = 16T
  22. Socket swivel carrier wheel = 72T
  23. Socket stud wheel = 13T
  24. Differential motion carrier wheel = 57T

Gearing Diagram:

Gearing diagram of speed frame to calculate no of coil per inch of roving bobbin
Fig: Gearing diagram of speed frame to calculate no of coil per inch of roving bobbin


We know,
Bobbin speed = 822
Spindle speed = 749

Therefore, Coils per minute = 822 – 749
= 73

calculation of roving bobbin
No. of coils per inch = 11.

Our teacher and lab assistants are very much helpful to us. Their well teaching and instruction help us greatly to understand this practical. I think this practical will be very helpful in my future career.

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