a ball bearing is a type of rolling-element bearing which uses balls to maintain the separation between the moving parts of the bearing.

Ball Bearing

a ball bearing is a type of rolling-element bearing which uses balls to maintain the separation between…

"When a ball is rolling on a horizontal plane, the centre of gravity is not raised, but moves in a straight line, parallel to the surface of the plane on which it rolls, and is consequently always directly over its centre of gravity." -Comstock 1850

Center of Gravity of a Rolling Ball

"When a ball is rolling on a horizontal plane, the centre of gravity is not raised, but moves in a straight…

"If the plane is inclined downwards, the ball is instantly thrown into motion, because the centre of gravity then falls forward of that motion, or the point on which the ball rests." -Comstock 1850

Center of Gravity of a Ball Rolling on an Incline

"If the plane is inclined downwards, the ball is instantly thrown into motion, because the centre of…

A mill furnished with heavy rollers, through which heated metal is passed, to form it into sheets, bars or rails.

Rolling-mill

A mill furnished with heavy rollers, through which heated metal is passed, to form it into sheets, bars…

A circular frame of hard material that may be solid, partly solid, or spoked and that is capable of turning on an axle.

Sheet Metal Web Wheel

A circular frame of hard material that may be solid, partly solid, or spoked and that is capable of…