Abstract: A reversible ratchet wrench has a handle portion and a head portion. The head portion includes a drive member having teeth thereon and a pawl having teeth which selectively engage the teeth on the drive member. The head portion has two partially overlapping cavities formed therein, the cavities being formed from the bottom of the head portion. The top of the head portion has two spaced-apart openings formed therein, each opening communicating respectively with one of the two cavities. The drive member is disposed in the larger cavity and the pawl is disposed in the smaller cavity. A one-piece lever means is provided having a non-cylindrical stem depending therefrom. The stem is received in a cooperating bore in the pawl. A multi-sided shelf is formed on the stem, the shelf being received in a cooperating cavity in the top of the pawl. The top of the head portion of the wrench is received between the top portion of the lever means and the shelf on the stem.

Abstract: A water recycling unit and system for dental operatories for use to supply operating priming water to liquid seal type vacuum pumps and including a conduit connectable to a municipal water supply, a solenoid valve in said conduit operated by a timer to open the valve for very short intervals periodically to furnish fresh makeup water to an air-water separator mounted above the level of the pumps and provided with a discharge to drain that is regulated to maintain a constant supply of contaminated water withdrawn from a patient's mouth and a small amount of the makeup water to comprise priming water delivered to the vacuum pump by gravity flow. The only moving element in the basic system is the solenoid valve and it only passes fresh municipal water free of impurities to insure complete closing of the valve and thereby obviate possible partial opening due to impurities lodged between the valve and its seat.

Abstract: This invention pertains to a water recycling system for economy in water consumption by dental evacuating equipment employing a water seal type pump and includes a storage tank for waste water received from the pump, a fresh water tank above the storage tank, and an air and water separator compactly arranged with said tanks, passage means between said tanks to permit makeup and flushing water to pass from the fresh water tank to the storage tank and flush the latter through syphon mechanism, except residual seal water remaining in the pump. Conduits extend from dental evacuating equipment to the pump and then to the air and water separator to vent air to atmosphere and pass waste water to the storage tank, and an additional waste water conduit extends in gravity-flow manner from the storage tank back to the pump for recycling and economy in water consumption.

Abstract: An operatory chair, such as a dental chair, having an upper supporting member to which the seat and back unit of an operatory chair may be attached, particularly pertaining to the mechanism by which said supporting member for the seat and back is raised and lowered. The preferred construction comprises a pair of sets of pivotally connected links arranged in lazy tong manner, said links being operated by linkage mechanism actuated by a rotatable screw and follower in such manner that the movement of the supporting member for the seat and back is smooth and relatively slow, particularly at the commencement of elevating movement so as not to include sudden and rapid upward movement as is conventional with typical lazy tong structures used in jacks and the like.