A speed limited wheel includes a wheel main body defining a cavity, a urethane wheel outer overmolded to the cavity, a brake hub and a plurality of brake elements. The brake hub is disposed in the cavity and includes a cylindrical flange. The wheel main body is rotatable relative to the brake hub about a wheel rotational axis. The plurality of brake elements is disposed in the cavity and is circumferentially surrounded by the cylindrical flange of the brake hub. Each brake element is pivotally mounted to the wheel main body for pivoting between a first position spaced apart from a cylindrical flange of the brake hub and a second position engaging the cylindrical flange of the brake hub for generating friction to reduce a rotational speed of the wheel. The speed limited wheel may be a caster.

A speed limited wheel includes a wheel main body defining a cavity, a urethane wheel outer overmolded to the cavity, a brake hub and a plurality of brake elements. The brake hub is disposed in the cavity and includes a cylindrical flange. The wheel main body is rotatable relative to the brake hub about a wheel rotational axis. The plurality of brake elements is disposed in the cavity and is circumferentially surrounded by the cylindrical flange of the brake hub. Each brake element is pivotally mounted to the wheel main body for pivoting between a first position spaced apart from a cylindrical flange of the brake hub and a second position engaging the cylindrical flange of the brake hub for generating friction to reduce a rotational speed of the wheel. The speed limited wheel may be a caster.

Brake discs, systems, and methods may include a brake disc and a brake drum. In various embodiments, the brake disc includes a central hub, configured to engage with an axial shaft. The brake disc includes protrusions, each of which is coupled to the central hub and extends perpendicularly from the central hub. The brake disc includes expansion components, each of which is coupled to the central hub at two locations. Each expansion component surrounds an outer periphery of one of the protrusions. The expansion components define a segmented periphery configured as a braking surface. The brake drum is configured to have an inner diameter that is larger than an outer diameter of the brake disc. The outer diameter of the brake disc is defined by the segmented periphery, such that an inner surface of the brake drum is concentric around the segmented periphery of the brake disc.

Brake discs, systems, and methods may include a brake disc and a brake drum. In various embodiments, the brake disc includes a central hub, configured to engage with an axial shaft. The brake disc includes protrusions, each of which is coupled to the central hub and extends perpendicularly from the central hub. The brake disc includes expansion components, each of which is coupled to the central hub at two locations. Each expansion component surrounds an outer periphery of one of the protrusions. The expansion components define a segmented periphery configured as a braking surface. The brake drum is configured to have an inner diameter that is larger than an outer diameter of the brake disc. The outer diameter of the brake disc is defined by the segmented periphery, such that an inner surface of the brake drum is concentric around the segmented periphery of the brake disc.

A door operator comprises a rotary shaft, a chain disk for rotating the rotary shaft, and a locking mechanism for locking the rotary shaft. The locking mechanism comprises a bidirectional rotary block, a plurality of push pins and anti-rotation posts. When the chain disk rotates, the push pins urge the bidirectional rotary block to rotate the rotary shaft, and when the rotary shaft rotates, the of anti-rotation posts lock the bidirectional rotary block, and preclude the rotary shaft from rotating.

A door operator comprises a rotary shaft, a chain disk for rotating the rotary shaft, and a locking mechanism for locking the rotary shaft. The locking mechanism comprises a bidirectional rotary block, a plurality of push pins and anti-rotation posts. When the chain disk rotates, the push pins urge the bidirectional rotary block to rotate the rotary shaft, and when the rotary shaft rotates, the of anti-rotation posts lock the bidirectional rotary block, and preclude the rotary shaft from rotating.

A door operator comprises a rotary shaft, a chain disk for rotating the rotary shaft, and a locking mechanism for locking the rotary shaft. The locking mechanism comprises a bidirectional rotary block, a plurality of push pins and anti-rotation posts. When the chain disk rotates, the push pins urge the bidirectional rotary block to rotate the rotary shaft, and when the rotary shaft rotates, the of anti-rotation posts lock the bidirectional rotary block, and preclude the rotary shaft from rotating.

A door operator comprises a rotary shaft, a chain disk for rotating the rotary shaft, and a locking mechanism for locking the rotary shaft. The locking mechanism comprises a bidirectional rotary block, a plurality of push pins and anti-rotation posts. When the chain disk rotates, the push pins urge the bidirectional rotary block to rotate the rotary shaft, and when the rotary shaft rotates, the of anti-rotation posts lock the bidirectional rotary block, and preclude the rotary shaft from rotating.

Brake discs, systems, and methods may include a brake disc and a brake drum. In various embodiments, the brake disc includes a central hub, configured to engage with an axial shaft. The brake disc includes protrusions, each of which is coupled to the central hub and extends perpendicularly from the central hub. The brake disc includes expansion components, each of which is coupled to the central hub at two locations. Each expansion component surrounds an outer periphery of one of the protrusions. The expansion components define a segmented periphery configured as a braking surface. The brake drum is configured to have an inner diameter that is larger than an outer diameter of the brake disc. The outer diameter of the brake disc is defined by the segmented periphery, such that an inner surface of the brake drum is concentric around the segmented periphery of the brake disc.

To provide a braking device that achieves unidirectionality without limiting the direction of rotation of a rotor. The present invention is characterized by being equipped with a housing (10), a rotor (20) provided inside the housing (10), brake shoes (30) provided between the rotor (20) and the housing (10), first protruding parts (40) that move together with the brake shoes (30), and second protruding parts (50) that move in conjunction with the rotation of the rotor (20), with the first protruding parts (40) riding up on the second protruding parts only when the rotor (20) rotates in the normal direction, and thereby generating greater friction between the brake shoes (30) and the housing (10) than the friction that can be generated between the brake shoes (30) and the housing (10) when the rotor (20) rotates in the reverse direction.