228) Torsional vibrations are said to occur when the particles of a body moves

229) A body is said to vibrate with simple harmonic motion if its acceleration is proportional to the distance from the mean position.

230) For the isochronous Porter governor, the controlling force curve is a straight line passing through the origin.

231) The virtual or equivalent eccentric for the Meyer's expansion valve is defined as an eccentric having such a length and angle of advance that will cause cut-off to take place at the same position, as is caused by the combined effect of main eccentric and e

232) The uniform pressure theory gives a higher frictional torque than the uniform wear theory.