11. The copper drive bands of the rounds were poorly machined, and constant firing was damaging the gun rifling. 12. The wider driving bands resulted in an increased weight to 10.4 kilograms for the PzGr . 39 / 43. 13. Over this, the expected barrel wear combined with the narrow driving bands could lead to a loss of pressure. 14. :The CVT consumes power in flexing the big rubber drive band which makes it a somewhat inefficient drive mechanism. 15. Other than minor differences with the projectiles driving bands , all German 75 mm guns used the same 75mm projectiles. 16. Because of the three wide equal width driving bands , the total bearing surface is half the length of the bullet. 17. While the spinner is making new yarn, the bobbin and the flyer turn in unison, driven by the single drive band . 18. The drive band turns the flyer, which is the horse-shoe shaped piece of wood surrounding the bobbin, as well as the bobbin. 19. Generally the speed difference or " ratio " is adjusted by the size of the whorls and the tension of the drive band . 20. Because of the three wide equal width driving bands , the total bearing surface is greater than half the overall length of the bullet.
