Abstract: A self-tracking recording tape is disclosed. The invention is primarily directed to thin base magnetic recording tape. However, the concepts of this invention are equally applicable to other recording tapes or film. Instead of a flat base tape, the tape of this invention is corrugated to form a plurality of V-shaped tracks across the width of the tape. The tape reels, the transport mechanisms, and the playback-reproduce heads utilized with the tape of this invention are all designed to accommodate the V-shaped grooves in the tape. In this manner, the tape becomes essentially self-tracking. That is, no auxiliary or additional guide means such as the edge guides normally used with magnetic tape recorders, are required to properly guide the tape across the head. In addition to the self-tracking feature, tapes designed in accordance with this invention can accommodate a large number of tracks across a given width of tape.

Abstract: A building block laying level indicating device adapted for use with a building block of general rectangular configuration wherein the block has a top and a bottom, front and rear walls and end faces. The front and rear walls of the block are connected by webs spaced from each other to provide a plurality of holes extending from the top through the bottom. The device has a planar base with three support members mounted thereon which are adapted to rest on the top of the block. A level indicating means is mounted on the base for visually indicating the level condition of the block. A positioning member is affixed to the planar base and extends downwardly therefrom so as to maintain the level in operating position when placed on the building block.

Abstract: Apparatus for mounting cabinets such as kitchen cabinets is disclosed. In addition, apparatus to provide for the mounting of trim panels above cabinets is disclosed. The cabinet mounting structure disclosed includes interlocking channel apparatus for mounting cabinets to walls and apparatus for mounting one cabinet to another cabinet with an adjustable space between the cabinets. The structure disclosed for accommodating trim panels above the cabinets comprises channel apparatus having formed therein channels for slidably housing the trim panels. The apparatus of this invention provides for a complete cabinet installation.

Abstract: A two piece check valve assembly comprising a retainer and a valve assembled thereto, the assembly having primary usage in hydraulic and pneumatic systems operating at a low differential pressure of fractions of ounces to over a hundred pounds per square inch. The check valve assembly comprises a retainer and a valve including a dome-shaped element and is adapted for use in a tubular member wherein the retainer grips the inner face of the tubular wall to position the valve assembly and the dome-shaped element fits against the inner wall of the tubular member. Pressure within the dome element causes it to expand and snugly engage the inner wall of the tubular member to cut off flow.

Abstract: A rail head re-form grinding machine is provided with an annular grinding wheel whose lower flat face is adapted to engage and grind the rail head. A circular feeler device fits within the annular grinding wheel and is also engaged by the rail head. The feeler device is vertically movable by a hydraulic piston arrangement the movement of the feeler device being sensed and indicated by a sensing and indicating assembly. The housing which mounts the grinding wheel and feeler device is pivotally carried so that an arcuate surface may be ground on the rail head.

Abstract: Method and apparatus for enhancing the directional content of information recorded or transmitted as four separate channels on a medium having only two independent tracks or channels and subsequently decoded into four signals each of which contains predominantly information pertaining to one of the four original channels but also information pertaining to others, in such a way that the resultant output signals when amplified and presented to four separate loudspeakers give the listener the illusion of four separate sources of sound.

Abstract: A clamp adapted for mounting on a flexible tube to control flow therethrough, said clamp having a pair of parallel legs connected by a spring element whereby the legs may swing toward and away from each other, a flexible catch arm on one leg having a catch adapted to engage a latch on the other arm, cooperating cam means on the catch arm and latch to swing the catch arm away from the latch upon movement of the latch carrying leg toward the other leg whereby the catch is cleared by the latch which allows the catch arm to swing toward the latch and engage same to retain the legs in close position, this movement causing confronting clamping elements on the legs to compress the tubing therebetween to close off flow. Openings are provided in the catch arm and spring element to frictionally receive the flexible tube and retain the clamp on the tube thereby.

Abstract: Ground fault detection circuitry for sensing ground fault currents is disclosed. If ground fault occurs in a line conductor(s) in a distribution system supplying AC power to a load, the circuitry senses this ground fault and provides a signal in response to the sensing of the ground fault. The circuitry also senses the grounding of a neutral conductor, or in some systems the shorting of a line conductor by a parallel conductive path and provides a signal in response to the grounding of the neutral or the parallel conductive shorting path. The signals provided by the circuitry in response to these sensed conditions may be used to provide a visual or audible alarm, or may be used to remove power from the load.