Abstract: A magnetorheological fluid clutch apparatus comprises an input(s) having an input shear surface(s). An output(s) is rotatably mounted about the input for rotating about a common axis with the input, the output(s) having output shear surface(s), the input shear surface and the output shear surface separated annular space(s), with magnetorheological fluid, configured to generate a variable amount of torque transmission between the sets of input rotor and output rotor when subjected to a magnetic field. An electromagnet(s) delivers a magnetic field through the magnetorheological fluid, the electromagnet configured to vary the strength of the magnetic field, whereby actuation of the electromagnet results in torque transmission from the input to the output. A member(s) defining at least one of the shear surfaces is made of a low-permeability material.

Abstract: A magnetorheological fluid clutch apparatus comprises an input(s) having an input shear surface(s). An output(s) is rotatably mounted about the input for rotating about a common axis with the input, the output(s) having output shear surface(s), the input shear surface and the output shear surface separated annular space(s). with magnetorheological fluid, configured to generate a variable amount of torque transmission between the sets of input rotor and output rotor when subjected to a magnetic field. An electromagnet(s) delivers a magnetic field through the magnetorheological fluid, the electromagnet configured to vary the strength of the magnetic field, whereby actuation of the electromagnet results in torque transmission from the input to the output. A member(s) defining at least one of the shear surfaces is made of a low-permeability material.