Theory of Machine
To obviate axial thrust, following gear drive is used

Single helical gear in which one of the teeth of helix angle a is more
Mutter gears
Double helical gears having opposite teeth
Double helical gears having identical teeth

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Theory of Machine
A rotor which is balanced statically but not dynamically is supported on two bearings L apart and at high speed of the rotor, reaction on the left bearing is R. The right side of the bearing is shifted to a new position 2L apart from the left bearing. At the same rotor speed, dynamic reaction on the left bearing in the new arrangement will

Become equal to R/4
Become equal to 2R
Become equal to R/2
Remain same as before

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