Patent ID: 8016210

Claim:
A nozzle assembly for mounting to a source of a high pressure fluid to spray the fluid, the nozzle assembly comprising: a housing having an inlet end for mounting to a source of high pressure fluid, an outlet end, an outer surface, and an inner surface defining an interior cavity; a shaft having an axis of rotation, an exterior surface, a fluid inlet end and an outlet end, said shaft having a central passage to conduct fluid axially from said inlet end of the housing axially from and through the inlet end of the shaft to said outlet end of the shaft and having a second passage between the central passage of the shaft and the exterior surface of the shaft, the shaft rotatably mounted within the interior cavity of the housing; at least a portion of the inner surface of the housing and at least a portion of the exterior surface of the shaft defining a pressure cavity chamber and further defining a regulating passage to allow a portion of the fluid to flow through the pressure cavity chamber and between the exterior surface of the shaft and the interior surface of the housing, the shaft further including an annular stepped shoulder portion joining the pressure cavity chamber; wherein fluid under pressure in the pressure cavity chamber causes a balancing force on the shaft in a direction substantially parallel to the axis of the shaft to counteract any axial force exerted by high pressure fluid from the source flowing into the inlet end of the shaft; and a spray head attached to said outlet end of the shaft to spray the fluid.