A guard is a device designed to prevent injury from rotating machinery.
Three concentric and rotating shafts would be known as a contra-rotating device. Currently, several machines like these are being designed, according to the US Patent Office.
a device that uses a positive means such as a lock to hold an energy isolating device in a safe position and prevent the energizing of the equipment and/or machinery being worked on
A guard is a movable device that provides a physical barrier between you and the point of operation. Guards are commonly used in machinery to protect individuals from potential hazards such as rotating parts or sharp edges.
A weightlifting device that must be prevented from rotating is called a non-rotating or fixed lifting beam. This type of lifter is designed to carry loads in a stable and secure manner without the risk of twisting or turning.
There are lots of device that rotate; one of them is a wheel.
A wheel clamp, is a device that is designed to prevent vehicles from being moved. In it's most common form, it consists of a clamp that surrounds a vehicle wheel, designed to prevent removal of both itself and the wheel.
A tachogenerator is a type of electromechanical device that generates an electrical signal proportional to the rotational speed of a shaft or motor. It typically consists of a rotor attached to the rotating shaft and a stator with coils that produce the electrical signal as the rotor spins. The generated signal can be used to measure and monitor the speed of the rotating machinery.
a propeller
a Propeller
a engine
knuckle joint
propeller.