51) When the axes of the shafts, over which the gears are mounted, move relative to a fixed axis, then the train is known as reverted gear train.

52) The gear train usually employed in clocks is a

53) The process of providing the second mass in order to counter act the centrifugal effect of first mass is called

54) The static balance is also called

55) When the inertia force and couples exerted by the moving parts are in equilibrium among themselves, then the system is said to be in