A rotational speed control device includes a housing containing a viscous fluid and a shaft disposed in the housing and rotatable relative to the housing. A rotor may be movable axially on the shaft depending on the rotating speed of the shaft. The rotor is biased in a low torque direction. A braking torque between the rotor and the housing and/or between the rotor and a drive control ring is varied according to an axial position of the rotor on the shaft. The device may incorporate bypass channels to control a circulating pressure of the viscous fluid.

An apparatus for retarding rotation of a nozzle includes a hollow housing, a rotary shaft within the housing, a rotatable rotor on the rotary shaft free to move axially along the shaft, and a cam assembly coupling the rotor and shaft together in the housing such that rotor rotation on the shaft causes the cam assembly to displace the rotor axially on the shaft in a first direction. A set of springs on the shaft biases the rotor in a second direction opposite the first direction on the shaft. Finally, a viscous fluid disposed between the rotor and the housing generates a drag on rotor rotation with the shaft. Relative rotation of the rotor with respect to the shaft in conjunction with a variable gap between the rotor and housing are used to slow and thus control rotary nozzle speed.

A rotational speed control device maintains a shaft rotation speed. The device includes a housing containing a viscous fluid and a shaft disposed in the housing and rotatable relative to the housing. A rotor is coupled with the shaft for rotation in the viscous fluid. The rotor is axially displaceable along the shaft between a low-shear position and a high-shear position. A spring mechanism is disposed in the housing and biases the rotor toward the low-shear position. The rotor may be designed to cooperate with the housing or other nonrotating features within the housing to vary a shear gap according to the axial position of the rotor. The rotor, housing and spring mechanism can be designed to cooperate to create large changes in braking torque in response to small changes in shaft rotational speed. This allows the rotation speed to be controlled within a relatively narrow range.

A rotational speed control device includes a housing containing a viscous fluid, a shaft disposed in the housing and rotatable relative to the housing, a hub assembly secured to the shaft for rotation with the shaft, and a rotor coupled with the shaft by a frictional engagement with the hub assembly. A spring is disposed in the housing and acts on the rotor to bias the rotor axially on the shaft in a low torque direction. A braking torque between the rotor and the housing is varied according to an axial position of the rotor on the shaft.

A rotational speed control device maintains a shaft rotation speed. The device includes a housing containing a viscous fluid and a shaft disposed in the housing and rotatable relative to the housing. A rotor is coupled with the shaft for rotation in the viscous fluid. In one arrangement, the rotor is axially displaceable along the shaft between a low-shear position and a high-shear position. A spring mechanism is disposed in the housing and biases the rotor toward the low-shear position. In another arrangement, the rotor may be designed to cooperate with the housing or other nonrotating features within the housing to vary a shear gap according to radially expanding components of the rotor. The rotor, housing and spring mechanism can be designed to cooperate to create large changes in braking torque in response to small changes in shaft rotational speed. This allows the rotation speed to be controlled within a relatively narrow range.

A brake system includes a series of rotors for operatively coupling to a shaft and stators for operatively coupling to a frame. A service brake system includes a singular annular service piston extending continuously around the series of rotors and stators and a parking brake system includes a singular annular parking piston positioned to extend continuously around the series of rotors and stators. The service piston nests with the parking piston, under a spring bias, such that the parking piston and service piston continuously engage together around the series of rotors and stators to thereby create the parking brake forces. Springs act on the parking piston to drive the parking piston and nested service piston to engage for parking brake forces. Pressurization of the parking piston deactuates the nested pistons. Then separate pressurization of fluid acts on the service piston to overcome the spring bias and separate the service piston from the parking piston to create service brake forces.