Abstract: A wire wound resistor is vertically disposed in a vessel. The resistor has a former of between 20 mm and 45 mm diameter and resistance wire of a resistance of between 1 and 4 ohms per turn connected in the circuit of an A.C. bridge circuit. Impedance change is indicated on a display unit calibrated to indicate the change in level of liquid e.g. milk in the vessel. The resistance wire is laid on the former by applying ultrasonic sound energy to soften the former which is of polysulfone or polycarbonate and the wire embedded in the softened former material. The vessel is shaped at the lower end to assist in giving linear readings when the level of liquid is low.

Abstract: The tumbler includes a connection between an outer gate ring and an inner drive member of a tumbler wheel together. The gate ring includes a leg on the gate ring with a gripping portion thereon. The leg normally biases the gripping portion to a securing position against the drive member to grip it so that the gate ring and drive member normally rotate together. An opening is provided in the gate ring adjacent the leg having a curved portion about its periphery for receiving a key having a curved portion about its periphery. The key rotates against the curved surface of the opening, and a cam section of the key cams a cam follower portion of the leg when the key is rotated to a releasing position for urging the gripping portion away from the drive member. The camming surface, opening and cam follower are so provided that on rotation of the key in the opening to the releasing position, the biasing effect of the leg is prevented from tending to return the key to the securing position.

Abstract: A double key changeable safety deposit lock includes a movable bolt and associated bolt plate including cam surfaces to be engaged and moved between open and closed positions by turning renter and guard keys in the lock, a plurality of gated tumbler renter key levers to be engaged by the renter key, a plurality of gated tumbler guard key levers to be engaged by the guard key, each of the levers being moved to align their respective gates to receive latch members on the bolt plate upon manipulation of the two keys to allow opening of the lock and wherein pivot means are provided for each lever including a plurality of individually selectable pivots such that the pivotal axis of each lever may be selectively varied to provide for different combinations of lever movement required by an associated key to align the associated gates.

Abstract: A changeable combination key lock for safe deposit boxes and the like, wherein a guard key is insertable into a rotatable guard key plug to set guard key tumblers to permit retracting movement of a bolt, and a renter's key is insertable into a rotatable renter's key plug for engagement with renter's key tumblers to aline them to permit retraction of the bolt. Both the renter's key tumblers and the guard key tumblers are releasable from gate members carried by the bolt and may be set for key configuration for a new renter's key and a new guard key, or either of them, when the lock is conditioned in a change mode to permit adjustment of the lock to operate with different guard keys and renter's keys.

Abstract: A combination lock has a plurality of gated tumbler wheels mounted for rotation relative to a gate entering bar portion of a release lever, blocking a release movement of such lever until gate openings on the tumbler wheels are aligned to said bar and a tumbler locator and lever arm actuator member mounted for both axial and rotative movement relative the axis of rotation of the tumbler wheels. The member has a drive pin engaging, and successively releasable from, drive apertures divided in the tumbler wheels to allow rotation of the tumbler wheels upon rotation of the member and sequential release of located tumbler wheels upon an axial movement of said member relative to said tumbler wheels.