A magnetic coupling is a coupling that transmits torque from one shaft to another, but uses a magnetic field instead of a physical mechanical connection. Electromagnetic couplings are most commonly used in hydraulic pumps and propeller systems because a static physical barrier can be placed between the two shafts to separate the fluid from the electric motor running in the air. Magnetic couplings cannot use shaft seals. The shaft seals will eventually wear out and fail due to the sliding of the two surfaces.
There are many sinker type magnetic couplings on the market today. The magnetic coupling consists of a bearing that contains a magnetic field from an electric motor, which creates a magnetic force to drive the shafts together. The shape and size of the magnetic wave or shape is very important. When two or more sinker type magnetic couplings are placed side by side there should be at least three magnetic waves interlocking with each other. This will keep all of them from slipping when they are not powered up. A magnetic coupling does not use bearings but it can carry high torque due to no friction between shafts