Abstract: A dental chair has an armrest pivoted to a base at an armrest pivot, and a seat back pivoted to the base at a back pivot located forward of the armrest pivot. The seat back includes a support pin for supporting the armrest at a position forward of the seat back pivot. Moving the seat back from an upright position to a reclined position through a large range of angular motion causes the support pin to elevate the armrest by a substantially smaller angular amount.

Abstract: A switch controller having a housing cover with a central ridge and opposed top surfaces which incline downwardly away from the central ridge. The top surfaces also incline on progressing from one end of the housing to the opposite end. A pair of footpads are mounted on the upper surface of the housing and incline consistently with their associated portions of the housing surfaces. The under surfaces of the footpads have spaced apart contact points thereon. Underlying the contact points are associated switches which are actuated by pressing downwardly on selected regions of the footpads. Fulcrum means are disposed between the associated pairs of contact points and switches to inhibit simultaneous actuation of adjacent switches.

Abstract: The chair includes a movable seat and back that are configured to enhance the patient's comfort by providing lumbar support when the chair is in the recumbent position and by minimizing patient sliding within a moving chair. Chair movement is controlled by a microprocessor-based control system that includes sensing mechanisms for precisely monitoring the chair position. The sensing mechanisms are employed in conjunction with a memory device to permit the user to define a particular position into which the chair will move any time the appropriate switch is closed by the user. The chair control system diagnoses malfunctioning chair components and generates and displays data indicating the particular malfunctioning component.

Abstract: The chair includes a movable seat and back that are configured to enhance the patient's comfort by providing lumbar support when the chair is in the recumbent position and by minimizing patient sliding within a moving chair. Chair movement is controlled by a microprocessor-based control system that includes sensing mechanisms for precisely monitoring the chair position. The sensing mechanisms are employed in conjunction with a memory device to permit the user to define a particular position into which the chair will move any time the appropriate switch is closed by the user. The chair control system diagnoses malfunctioning chair components and generates and displays data indicating the particular malfunctioning component.

Abstract: The chair includes a movable seat and back that are configured to enhance the patient's comfort by providing lumbar support when the chair is in the recumbent position and by minimizing patient sliding within a moving chair. Chair movement is controlled by a microprocessor-based control system that includes sensing mechanisms for precisely monitoring the chair position. The sensing mechanisms are employed in conjunction with a memory device to permit the user to define a particular position into which the chair will move any time the appropriate switch is closed by the user. The chair control system diagnoses malfunctioning chair components and generates and displays data indicating the particular malfunctioning component.

Abstract: A labyrinth seal for sealing an impeller shaft within a pump housing. The seal includes inner and outer coaxial, relatively rotatable members secured to the shaft and the housing, respectively. Defined between the two members is a succession of axially extending sleeve-shaped passages of decreasing diameters progressing toward the pump interior, these passages being connected by radially extending disc-shaped passages. Fluid moving through the sleeve-shaped and disc-shaped passages flows into annular grooves formed at the ends of these passages, setting up currents which resist fluid flow through the seal.