Abstract: A bowl for a centrifuge for clarifying or separating mixtures of liquids. The bowl has a valve or slide that is maintained in the closure position by a closure fluid. The closure fluid circulates at the same angular velocity as the bowl. A closure chamber containing the closure fluid is associated with the bowl. To decrease the consumption of closure fluid, the opening motion of the valve or slide is initiated by closure fluids that act on the closure fluid in a direction opposite the one that the bowl is rotating in and that decrease the angular velocity of the closure fluid and hence the closure force exerted on the valve or slide while the bowl continues to rotate at full operating speed.

Abstract: A rotatable tire brush for a vehicle washing apparatus, which brush includes a plurality of abrasive bristles defining a first cylindrical array, and a plurality of nonabrasive bristles defining a second cylindrical array. The abrasive and nonabrasive bristles are dispersed in a uniform pattern throughout the first and second cylindrical arrays, and the outer diameter of the second cylindrical array is greater than the outer diameter of the first array. The tip ends of the nonabrasive bristles are preferably flagged to provide the brush with an outer fluffy layer.