Abstract: In a preferred embodiment, a computer key-punch work-station structure having a copy support shelf mounted behind a key board shelf's forward portion and above a rearward portion thereof, mounted adjustably of height at its rearward edge and thereby varable of tilt of the copy support shelf, and a video display-screen support shelf being mounted behind the copy support shelf and being adjustable of both height and tilt angle. This combination is mounted on bilateral unified leg structures having separate forward and rearward upright legs connected at their bases and connected at their upper portions by a horizontal weight-distributing support, with the tops of the leg structures being braced against sideward wobbling.

Abstract: In a preferred embodiment, a seating structure for a dental instrument, provided with a forward port for retractably receiving a dental instrument into the seat and provided with a rearward port for travel of an air tube connected operably to the dental instrument, has an open top with a minor overhang and with a narrowed width at the rearward port, and a forwardly mounted arched channel structure defining a through space of a height sufficient for travel of the air tube above the overhang, and including the air tube with a slidable retainer ring mounted thereon and axially adjustable to and fro to alternate positions as might be desired, with the retainer ring having a width greater than width of the open top adjacent the overhang but of a dimension sufficiently small to be retracted through the forward port into the seat beneath the overhang, the arched channel structure providing a guide track within which the tube may be flipped when the retainer ring is forward of the forward port, in orderto cause the r

Abstract: A fan drive system comprises a constant pressure ring main circuit from a motor driven pump to, for example, three variable capacity motors driving three fans. The motors are connected in parallel with each other and in series circuit with the pump and each has a piston and cylinder device supplied with pressure from the ring main. A variable restrictor controlled by a temperature probe sets the pressure acting on each piston and cylinder device so that each fan is speed controlled in accordance with temperature.

Abstract: In a preferred embodiment, a base structure affording upright support for a substantially horizontally mounted tray providing for movement of the tray slidably forwardly and backwardly intermittently optionally to desired degrees, and providing for forward and backward slant and for slant in either direction intermittently to desired degrees optionally, the tray having an upper surface defining a plurality of parallel grooves open at the forward ends thereof with the forward opening structure of at least one of the grooves defining a constriction in the groove and thereafter a forward widening thereof terminating as an abrupt step, and there being a mechanized tool of dentistry attached to a tubular connector having a forward end defining a downward projection such that the downward projection engages the step when the tubular connector is in a withdrawn state and there being an outer casing having a spiral ridge on the outer surface thereof mounted slidably over a portion of the tubular connector and definin