Abstract: The present invention is a valve system for exhausting air from a brakepipe in a remote portion of a train. It has a pressure containment structure having a cylindrical bore and a piston mounted in the bore. A first valve chamber is on one side of the piston and a second valve chamber on a second side. A diaphragm seals between piston and bore, the diaphragm having an annular fold for permitting movement of the piston within the bore. The system has a first brakepipe pressure passageway for conveying air from the brakepipe to the first valve chamber and a control pressure connection for conveying air from a control chamber to the second valve chamber. A biasing means is provided for urging the piston toward the first valve chamber.

Abstract: The present invention provides an adapter member for attaching a pressure transducer to a housing member which has a fluid pressure communication passageway. The pressure transducer has a threaded fitting having a fluid pressure communication passageway for connection to a fluid communication line, such as an air hose. The pressure transducer has a mounting arrangement for attachment to a surface, such as a panel. The adapter member has a first body portion having a threaded fitting for mating with the threaded fitting of the pressure transducer and the adapter member has a fluid pressure communication passageway. A portion of the adapter member has an axisymmetric external surface portion for sealing against an inner surface of the fluid pressure communication passageway in the housing member.

Abstract: A method for fabricating a dual element head is disclosed. One embodiment includes first depositing a first head element upon a substrate and second depositing a second head element upon the first head element. Each of the depositing steps includes a tolerance that is independent of the other. In the second depositing step, the functional width of the second head element (i.e., the write width if the second head element is a write element) is made wider than a desired functional width for the second head element. The second head element is then trimmed to substantially achieve the desired functional width while using a portion of the first head element as a reference to reduce errors associated with the independent nature of the first and second tolerances. For instance, the portion of the first head element used as a reference can be an edge of a magnetoresistive (MR) read element that defines the read width of the read element.

Abstract: Choke for connection to a fluid flow passage for controlling fluid flow through the passage in a predetermined direction. The choke has structure for attachment to the fluid passage. It also has an internal fluid flow passage, which has at least one constriction. One or more mesh filters are located in the internal fluid flow passage of the choke, upstream of the constriction, to remove debris from the fluid which would otherwise interfere with fluid flow through the orifice.

Abstract: Adaptive channel optimization in a disk drive is achieved by selecting a track of the recording medium and then writing a first data pattern to opposite sides of the selected track. The first data pattern is written a certain percentage off-track in relation to the centerline of the selected track. A second data pattern is then written directly on the selected data track and the off-track margin is determined as a function of how far the recording head can be positioned away from the center of the selected track during reading of the second data pattern while meeting a specified error rate. The off-track margin test is repeated iteratively using a combination of channel variable settings in order to find a set of variable settings which provides an optimal performance criteria for the drive.

Abstract: The present invention relates to circuitry for processing an analog read signal, such as a signal produced by a magnetoresistive head, in a magnetic data storage system. The circuitry processes the analog signal before the signal reaches the detector which converts the analog signal into a digital signal representative of the data originally stored on the magnetic medium. In one embodiment, the invention comprises circuitry for equalizing the amplitudes of the positive and negative pulses in the analog read signal. In another embodiment, the invention comprises circuitry for reducing the baseline shift of the analog read signal. The invention may be used in magnetic data storage systems using any conventional data detection method.

Abstract: A dual element head is provided that includes a read element and a separate write element, wherein the read width of the read element is greater than the write width of the write element. The head also includes an erase notch for creating an erase strip along the edge of data written by the write element during a write operation. The width of the erase strip is optimized so that undesired data on the track, that could otherwise be read by the wider read element during a subsequent read operation, is removed during the write operation.

Abstract: The present invention is directed to a disk drive that employs a proximity recording interface in which a slider that carries a head is designed to remain in contact with the disk during data transfer operations to achieve a high data density. In particular, the present invention is directed to cleaning debris from a pad on the slider that carries the head. The debris, if allowed to accumulate, can reach a depth at which the head is spaced from the disk at a distance which adversely affects the transfer of data with the disk. In one embodiment, the spin motor of the disk drive is caused to rotate at a lower angular velocity than during normal data transfer operations while the actuator of the disk drive is used to radially displace the slider and associated head. For a constant angular velocity of the disk, the change in radial position causes different areas of the pad to be contacted and cleaned by the disk.

Abstract: A resonant frequency control circuit communicates with a head of a disk drive and the preamplifier of a read channel. The resonant frequency control circuit is useful in achieving peaking of a readback signal generated by reading data from a magnetic disk. The read channel also includes an equalizer circuit for enhancing equalization of the readback signal. A controller communicates with the read channel and the resonant frequency control circuit for, in one embodiment, selectively adding capacitance to that capacitance which is present in the read element of the head and the preamplifier. By controlling the resonant frequency, this desired signal peaking can be achieved, which is related to the frequencies of the coded data on the disk.

Abstract: A magnetic head that creates erase bands on the outer edges of a track. The magnetic head has a trailing edge pole that is separated from a leading edge pole by a gap. The leading edge pole has a width that is less than the width of a center section of the trailing edge pole. The thinner leading edge pole creates a saturation of the magnetic field at the outer edges of the leading pole. Saturation at the outer edges of the leading pole prevents a full magnetization of the disk along the outer edges of the track. The poorly magnetized outer track portions will not generate a significant amount of noise in a head located above an adjacent track. The saturated outer leading pole edges in effect create an erase band along the outer edges of the track.

Abstract: A magnetic head that vertically records information on a disk and which creates erase bands between the disk tracks. The head has a single pole that has a pair of erase band segments which extend from a center pole section. When the head is writing information, the erase band segments create erase bands at the outer edges of the track by not fully magnetizing the disk and/or increasing the azimuth angle of the magnetized outer edges. The azimuth angle can be increased by constructing the outer segments of the pole to extend at an angle from the center pole section. The reduction in field strength in the outer track edges can be accomplished by making the outer pole segments thinner to cause a saturation of the outer magnetic field. The weaker, angled outer track portions do not generate a significant magnetic field in a head located on an adjacent track, thereby in effect creating erase bands in the disk.

Abstract: There is provided a method for producing erase bands of varying width between tracks of information on a recording medium. In accordance with the method, a magnetic head having a write gap and trailing pole with non-parallel portions is produced. In the preferred embodiment, the magnetic head combines an inductive write head with a magneto-resistive read head in a single head structure. The inductive head includes a leading write pole and a trailing write pole which are separated by a recording gap. The write gap is formed with a central portion writing data in a desired orientation, positioned between two non-parallel side portions having divergent angles with respect to the central portion. In the recording process, the side portions write transitions on the recording medium which are oblique or angled with respect to the data transitions written on the medium by the central portion.

Abstract: A method of constructing a ferrite magnetic head that can be used for vertical recording. The head is created by first bonding a non-magnetic shoe to the legs of a C-Shaped magnetic core to create a block assembly. A pole surface of the block is then lapped and sputtered with a magnetic pole material. A layer of alumina is then sputtered onto the magnetic pole material. After sputtering, the block is ground to create air bearing grooves and a plurality of poles. The bearing surface of the block is then lapped to the apex of an oblique interface between the shoe and core to create the throat of the pole. The block is cut into individual transducer cores which are then wrapped with a wire coil and attached to a flexbeam.

Abstract: The present invention provides a method for producing erase bands of varying width between tracks of information on a recording medium. In accordance with the invention, a magnetic head having a write gap and trailing pole with non-parallel portions is produced. In the preferred embodiment, the magnetic head combines an inductive write head with a magneto-resistive read head in a single head structure. The inductive head includes a leading write pole and a trailing write pole which are separated by a recording gap. The write gap is formed with a central portion writing data in a desired orientation, positioned between two non-parallel side portions having divergent angles with respect to the central portion. In the recording process, the side portions write transitions on the recording medium which are oblique or angled with respect to the data transitions written on the medium by the central portion.

Abstract: The present invention discloses texturing of the slider air bearing surfaces of the magnetic heads in disk drives to reduce stiction that retards take-off and displaces critical lubricant in a magnetic head system. One embodiment of the present invention utilizes nonuniform etching of chemically identical components of a ferrite slider material due solely to random crystal orientation relative to the exposed surface. Another embodiment of the present invention utilizes a photoresist of a type used in making printed circuit boards, to form a pattern. Subsequently, the surface may be etched to form the antistiction properties. A variety of controlled and reproducible patterns as well as a controlled depth of pattern may be utilized.

Abstract: The present invention discloses texturing of the slider air bearing surfaces of the magnetic heads in disk drives to reduce stiction that retards take-off and displaces critical lubricant in a magnetic head system. One embodiment of the present invention utilizes nonuniform etching of chemically identical components of a ferrite slider material due solely to random crystal orientation relative to the exposed surface. Another embodiment of the present invention utilizes a photoresist of a type used in making printed circuit boards, to form a pattern. Subseqeuntly, the surface may be etched to form the antistiction properties. A variety of controlled and reproducible patterns as well as a controlled depth of pattern may be utilized.

Abstract: An apparatus for loading and unloading a magnetic head assembly on a magnetic recording surface which permits separation of function between load/retract and flying and which produces a predictable pitch to the magnetic head assembly in the static condition and no pitch bias in the dynamic flying condition. The present invention improves on the IBM type 3370 by adding to the single piece spring/load beam element a pair of wings which extend laterally on each side thereof and a pair of stationary cam members positioned on opposite sides of the element. The arrangement of the torque wings and cams permits unrestricted retraction of the slider. The placement of the wings results in a favorable ratio of lift point to load beam bending point and more control of load zone accuracy.

Abstract: In a magnetic disc drive, there is disclosed a method for cleaning the magnetic disc surfaces and the heads. The heads are loaded and caused to fly on the disc surfaces. The spindle motor speed is reduced to a speed where the heads fly at approximately 50% of the normal flying height and the head support structure drive motor is commanded to sweep the heads across the disc surfaces, forward and reverse, for several cycles, to remove any particles down to an elevation that is 50% of the normal flying height. The heads are then positioned over unused tracks on the disc surfaces and the spindle motor speed is reduced to a speed where the heads fly at approximately 25% of the normal flying height so as to scrub off any particles left on the heads. The spindle motor speed is then returned to normal speed and a 25% margin of interference-free operation has been assured.