Abstract: In an automatic train-line air brake pressure monitoring system, a peak detector and hold circuit determines the peak voltage of an input signal representing the air pressure in the air brake system. A signal representing the present peak voltage of the input signal from the previously detected peak voltage is subtracted from the presently detected peak voltage to provide a subtraction output signal such that signals representative of the air brake pressure can be generated. The monitoring system may provide emergency air brake condition signals, as well as a number of programmable monitoring signals representative of different pressures within the air brake pressure system.

Abstract: A method and apparatus for sensing air pressure in pneumatic suspension units for a vehicle, such as a motorcycle, comprising: air pressure sensors capable of sensing air pressures in pneumatic suspension units to generate an output signal when the air pressures are below a predetermined level; a vehicle speed sensor capable of sensing vehicle speed to generate an output signal when the vehicle speed exceeds a predetermined level; a signal processor adapted to receive output signals from the pressure sensors and the vehicle speed sensor and generate an output when the air pressures in the pneumatic suspension units are below a predetermined level while the vehicle speed continues to be in excess of a predetermined level for more than a predetermined period of time. An indicating device produces an indicating signal when it receives an output signal from the signal processor.

Abstract: A burglar alarm system to detect the breaking of a pane of a sealed multiple pane panel comprises in one embodiment a sensor responsive to the humidity intermediate the panes of the panel, a burglar alarm, and a microprocessor or detector operably connected to the sensor and alarm, the detector being adapted to actuate the alarm when the sensor detects a change in the humidity. In a preferred embodiment the system comprises a sensor responsive to an atmospheric parameter (such as humidity or pressure) intermediate the panes of the panel, a burglar alarm, a slow leak warning device, and a detector operably connected to the sensor on the one hand and the alarm and warning device on the other hand.

Abstract: A crack indicator based on a piping system consisting of cold-embrittling plastics pipes imbedded in a gas container insulation. A warning gas is subjected to an excess pressure in the piping system. In the event of a crack or other damage to the insulating material, a leak is produced in the piping system at this point so that warning gas flows out into the tank interior. In this case, an indicator responding to the issuing warning gas produces an alarm signal. The alarm emitter can consist, for example, of an analysis instrument for the specific gas. However, an indicator based on a pressure measuring system which is connected upstream of the piping system and produces an alarm signal when a predetermined pressure difference is exceeded is simpler.

Abstract: A liquid activatable alarm device for providing continuous monitoring of the presence or absence of a patient in a hospital bed. When the patient attempts to leave the bed, a pressure sensitive switch responds sounding an alarm warning the hospital staff.

Abstract: A self-resetting warning actuator (42) for a vehicle brake system includes a housing (27) having a bore (44) which defines a recess (58). A pair of pressure responsive pistons (50, 54) are received in the housing bore and each is exposed to the pressure in one brake circuit. A roller member (48) is disposed in the housing recess and between the pistons. When the brake system is operating normally, the pressures in the two brake circuits are substantially equal and the pistons define a neutral position. Should one of the circuits fail, the pistons are shifted from their neutral position by the resulting pressure difference between the circuits. The housing recess defines a ramp which forces the roller member between the pistons when the pistons shift from their neutral position. A signaling device, by its response to the movement of the pistons, provides a warning to the vehicle operator.

Abstract: A detector for providing an audible indication of the vacuum condition for use in promoting the economic operation of a vehicle including a vacuum detector for detecting the magnitude of the vacuum condition in the manifold vacuum line of a vehicle to effect a switch closure which energizes an audible alarm. The vacuum detector comprises a piston reciprocally mounted within a piston chamber and movable responsive to changes in vacuum. A piston rod is arranged between combination switch and guide means for maintaining the axial alignment of the piston rod and for cooperating with conductive means arranged along the piston rod for establishing a conductive path for energizing the audible alarm when a predetermined vacuum condition is present. The contact design provides automatic silencing of the alarm when the engine is turned off or upon demand of engine power beyond a predetermined value. The small size allows for an out-of-sight dashboard mount without affecting operator recognition of the alarm.

Abstract: Tire pressure monitors are incorporated in vehicles having penumatic tires (14) to continuously or periodically measure the air pressure within the tires and to alert the driver should the pressure in one of the tires fall below a predetermined value. A self-contained battery powered rf transmitter unit (10) is affixed within the drop center (22) of each wheel (12) and includes a pressure sensing switch (84). The battery is contained within a housing (20) mounted to the external surface of the wheel adjacent a fill valve (30) through which electrical wires (50) are routed to the transmitter (11). The transmitter emits a pulse every 33 seconds when the air pressure within the tire is above a prescribed value. A receiver (13), located in the passenger compartment of the vehicle, receives the signal(s) from the transmitters and counts the number of signals received over a given time period established by an internal pulse generator.

Abstract: A self-contained, electrically-isolated patient call device is provided which permits use by quadriplegic or partially paralyzed patients which includes an extremely sensitive, adjustable, non-sealed, pneumatic, pressure transducer activated by the patient which in turn produces a simultaneous movement of an actuation transducer which actuates an electronic circuit. The switch and electronic circuit can produce both an audible alarm signal and activation of electrical contacts to simultaneously operate a nurse call system. The transducer activated by the patient can be actuated by a minor flexation of a muscle or skin area or can be the result of air pressure created by the breath or blowing against the transducer. This device permits electrical isolation of the patient to prevent shock and allows pneumatic activation of the system mounted directly on or close to the patient to eliminate the necessity for extended movement or positional adjustments which are usually impossible for the patient.

Abstract: A leak detection apparatus (18) is provided in a pressurized assembly (10) to signal a loss of pressure or vacuum downstream from a source of pressure or vacuum. A rod (60,160,260) is carried on a valve (62,162) and a diaphragm (38,138) which seals the source of pressure or vacuum from the system. A loss of pressure or vacuum downstream of the valve (62,162) and diaphragm (38,138) moves the rod (60,160,260) to a signalling position to alert an interested party that the system is lacking pressure or vacuum.

Abstract: A pressure sensing device has a light source, and an optical sensor for externally sensing a predetermined change in the pressure within a sealed system which has a conventional gauge. Illumination from the light source is reflected off of the gauge dial and detected by the optical sensor. When the pressure in the sealed system changes a predetermined amount, the needle on the gauge moves so as to interrupt the illumination reaching the optical sensor. The optical sensor in turn produces a voltage that can be used to turn on a light or other indicator.

Abstract: A diaphragm type actuator with a breakage condition detecting function which comprises a diaphragm member partitioning a casing into a first chamber filled with a high pressure and a second chamber exposed to air, and a breakage detecting switch supported by a displaceable partitioning member, such as, bellows, provided on the inner wall of the first chamber so as to define a third chamber filled with a high pressure, whereby if there occurs breakage in the diaphragm, the breakage detecting switch mounted on the bellows moves towards the diaphragm member to become in contact with an actuating rod supported by the diaphragm member to detect the breakage in the diaphragm member.

Abstract: A switch mechanism includes a fixed contact bar on which two or more contacts may be mounted. A movable contact is associated with each of the fixed contacts. Two independent toggle mechanisms are provided, each responsive to a different pressure-responsive displacement actuator for selectively actuating one or more of the movable contacts. In one embodiment having two normally open and one normally closed set of contacts, one toggle mechanism is connected by a sliding yoke to the movable contacts of one normally open set and the normally closed set, and the other toggle mechanism is connected by a second, independent sliding yoke to the movable contacts of the other normally open set and the normally closed set. Hence the normally closed contacts (which may be used to de-energize a compressor motor) are opened if either pressure limit is exceeded, but only the normally open set is disclosed which is associated with the tripped toggle mechanism. This may be used to indicate an alarm.

Abstract: A pressure relief indicator including a housing connected in fluid communication with a fluid system to be relieved, a pair of rupturable diaphragms extending in closing relation across the housing and combining to define a closed chamber, the diaphragm adjacent to the system rupturing at a predetermined desired relief pressure and the other diaphragm rupturing at a lesser pressure, a pressure supply maintaining a control pressure in the chamber of a value between atmospheric pressure and the lesser diaphragm rupturing pressure, and an annunciator responsive to change in pressure differential between the chamber and atmosphere as upon rupture of the diaphragms.

Abstract: An electrical switch assembly is shown as having a housing carrying three electrical terminals with first and second of such terminals respectively terminating in first and second fixed electrical contacts and the third of such terminals being electrically connected to a conductive spring; a further third fixed electrical contact, spaced from the first and second fixed contacts of the first and second terminals, has an aperture formed therein permitting the extension therethrough of an actuator which in turn carries a movable contact which is situated generally between the third fixed contact and the first and second fixed contacts with the spring engaging and urging the movable contact and actuator in a direction whereby the movable contact is moved toward the third fixed contact; a pressure responsive diaphragm situated generally at a side of the third fixed contact operatively engages the actuator and upon sensing sufficient pressure is effective to move the actuator and movable contact against the spring

Abstract: An elongated cylindrical member, such as an axle, a bolt, stud, rivet, supporting column, etc., has means for the in situ detection and indication of cracks therein. The member is generally solid and includes, in accordance with the invention, a cavity extending inwardly from at least one end of the member and terminating in a bottom surface of the cavity. A plurality of holes extend inwardly from the bottom surface of the cavity and are disposed in circular arrangement around the bottom surface of the cavity and adjacent to the periphery of the member. A ring member is disposed in the cavity, the bottom surface of the ring member being spaced from the bottom surface of the cavity to define a chamber therebetween. An opening extends through the ring member from the top surface to the bottom surface thereof, and valve means are inserted in the opening to permit the insertion of gas under pressure into the chamber and into the holes.

Abstract: An overpressure device is disclosed for use in a liquid infusion set for the purpose of detecting excessive pressures which may occur during infusion. The device comprises a tubular member with an inlet and an outlet, a closed pressure chamber and a bridging portion containing a small bore passage which connects the pressure chamber with the tubular member. In a preferred form, the interconnecting passage takes a tortuous path. An optical sensor positioned on the pressure chamber will detect the presence of liquid at a predetermined position in the chamber, when the liquid rises as a result of excessive pressure in the set, and respond by stopping the flow of liquid in the set.

Abstract: The invention concerns a device indicating a state due to the pressure modification, in particular an overpressure or a vacuum pressure switch for the indication of the fullness of the dust bags in household or industrial vacuum cleaners with a diaphragm exposed on one side to the variable pressure and with a contacting action between two contact elements as caused by the diaphragm's movement.

Abstract: A system to warn an aircraft pilot of a hazardous wind shear condition in which the rate of change of airspeed is compared to the ability of the aircraft to respond thereto. Any difference therebetween that exceeds a predetermined threshold is used to activate a suitable alarm or compensation device. Additional refinements include correcting the inertial speed inputs for vertical components and autopilot induced throttle changes, and correcting the air speed inputs for short term fluctuations.

Abstract: Pressure drop detectors are provided which are suitable for use in pressurized fluid fire alarm systems. The pressure drop detectors have pressurized fluid circuits provided as channels in the surface of a block of material, including one channel connected to a source of fluid pressure. The channels are associated with valve regions by means of which, with a first diaphragm pressed thereagainst, a required one or more of the channels can be closed off.The pressure drop detectors have a normally pressurized region of the first diaphragm which by means of a first piston normally supports a mechanical linkage of the detector. If the pressure drops however on release of pressure in the circuit connected to the detector, the collapsing of the first diaphragm allows the mechanical linkage to be released thus actuating a fire alarm.

Abstract: An arrangement for installing electronic counters in a petrol pump comprising a pressure-tight casing for accommodating the counters, means for providing an excess air pressure in the interior of the casing and a pressure-controlled switch inside the casing for interrupting the current supply to the counters when the pressure falls below a specific level.

Abstract: An overtravel indicator for a piston received in a cylinder having an end wall toward which the piston moves includes an elongated indicator rod slidably mounted through a dielectric bushing in the end wall. A conductive garter spring is compressed between the indicator rod and a groove in the cylinder end wall. An electric circuit including an electrically operated indicator is connected for completion through the indicator rod, end wall and garter spring. In an inward armed position of the indicator rod, dielectric material carried by the rod is interposed between the rod and garter spring for opening the electric circuit. In an outward operated position of the rod, a conductive surface on the rod engages the garter spring to complete the circuit and operate the indicator.

Abstract: A piston overtravel indicator for indicating overtravel of a piston from a rest position adjacent one end of a cylinder to working positions displaced from the rest position toward the other end of the cylinder. The indicator includes an elongated indicator rod slidably extending through a hole in the other end of the cylinder and having an inner rod end located within the cylinder adjacent the working positions of the piston. Overtravel of the piston beyond working positions causes engagement of same with the inner rod end for moving the rod outwardly through the hole. The indicator rod has a circumferential groove adjacent the inner end thereof for cooperation with a yieldable abutment extending into the hole for preventing complete outward displacement of the indicator rod through the hole.

Abstract: A gas charged accumulator includes a gas chamber and a hydraulic reservoir on opposite sides of a movable member. A fill passage for pressurizing the gas chamber includes a movable operating device for operating an indicator when the accumulator is substantially discharged. Gas flows directly past the indicator operating device when the gas chamber is pressurized through the fill passage. A normally closed switch assembly is mounted in the fill opening outwardly of the indicator operating device subsequent to pressurization of the gas chamber. The indicator operating device holds the switch assembly in an open position when the accumulator is charged and provides closing of the switch when the accumulator is substantially discharged.

Abstract: An overtravel indicator for a piston received in a cylinder having an end wall toward which the piston moves includes an elongated indicator rod slidably extending through the end wall. The rod has an armed position extending inwardly of the end wall and an operated position extending outwardly of the end wall. An electrically operated indicator is positioned in a circuit connected for completion through the indicator rod and end wall when the rod is in its operated position. In the armed position of the rod, dielectric material surrounds that portion of the rod extending through the end wall for opening the electric circuit. In the operated position of the rod, its outer surface engages the end wall for completing the electric circuit.

Abstract: A device for controlling the pressure in an inflatable cuff surrounding an endotracheal or tracheostomy tube is described.

Abstract: A trigger device for an explosion barrier includes a pressure sensor and at least two flame sensors. The pressure sensor energizes the flame sensors in response to a predetermined pressure rise, and the explosion barrier is triggered when a flame is detected by both flame sensors. The flame sensors are oriented at different angles in order to prevent false firing by miner's lamps, etc.

Abstract: An industrial type switch having modular parts which may be assembled so the switch may be used in a wide range of installations. The switch includes a differential module which is easily adjustable to operate over a selected range of pressures, a plug-in snap switch module so the switch may be easily wired and serviced, a range module so the response of the switch to pressures within a range may be readily accomplished, and any one of a plurality of different type actuator modules which are mountable on the exterior of the switch so the switch may be used in a large variety of different type installations.

Abstract: A hydraulically actuated device secures the back end of a truck against a surface of a loading dock during loading and unloading of the truck. The device includes a self-aligning hydraulic cylinder which is adjustably mounted on the loading dock, and a piston mounted within the cylinder and having an exposed portion to which an attaching means is connected. The attaching means is adapted to be releasably connected to the truck. Control means is provided for directing hydraulic pressure to the cylinder so as to effect movement of the piston in one direction whereby the attaching means exerts a pulling force on the truck to cause the latter to be secured against the loading dock surface, or in a second direction whereby the attaching means assumes a position wherein it may be disconnected from the truck. Signal means, responsive to hydraulic pressure, is provided to indicate when hydraulic pressure is being, or not being, exerted on the piston.

Abstract: A fluid-filled electrical bushing for connecting an electrical conductor in a fluid-filled transformer to an electrical conductor in another enclosure. The electrical bushing includes a safety device consisting of two coaxial flexible capsules which are joined to a plate disposed therebetween and which respectively communicate with the dielectric fluid in the bushing and with the dielectric fluid in the transformer. The plate, which is movable in opposite axial directions in response to the pressure difference between the dielectric fluid in the bushing and the dielectric fluid in the transformer acting thereon, alternately engages first or second electrical contacts to complete an electrical circuit indicating an over-pressure condition caused by internal arcing, or the abnormal expansion or an insufficient amount of dielectric fluid within the bushing.

Abstract: An installation for the protection of a line, according to which the line is surrounded at least within its area endangered by external influences by a coaxially arranged tubular member and the annular space disposed between the line and the tubular member is filled by a control medium which triggers a warning indication in case of an unusual pressure change caused, for example, by mechanical damage to the outer tubular member.

Abstract: In a pressure differential warning actuator for detecting when a differential between the pressure of separate brake circuits of an hydraulic braking system exceeds a predetermined value, at least two separate pistons work in separate bore portions in a common housing and are movable between a neutral position when the predetermined value of the differential pressure is not exceeded and an operative position, in which an indicator mechanism is actuated, when the predetermined value is exceeded, and the pistons act through a lever ratio change mechanism to restore them from the operative position to the neutral position when the differential is reduced to less than the predetermined value.

Abstract: A monitor adapted for use with a pneumatic tourniquet having a pressure supply line, the monitor including an alarm which is actuated via a low pressure sensor or a high pressure sensor when the tourniquet pressure falls below or rises above predetermined minimum or maximum pressure levels, respectively, and an elapsed time indicator providing a perceivable indication of the total time during which the tourniquet has been pressurized.

Abstract: A solid state dual timer with adjustable "long" and "short" time intervals preferably providing a long normally operating period between consecutive test periods which are utilized for test purposes, wherein a "delay" interval is provided at the initiation of each test period to allow the test conditions being imposed a sufficient time to settle. A highly advantageous application resides in the field of automated lubrication systems in which periodic pressure tests to monitor system integrity are performed, for example, every hour, the tests requiring a relatively brief time interval, the "delay" interval being of a length sufficient to allow the system pressure to build up before the test instruments are activated. The normally operating interval and the test and "delay" periods are all adjustable.

Abstract: Apparatus for monitoring the pressure in a gas line and providing a visual and audible indication of a high or low pressure condition, the gas line having a pressure sensor for generating high and low pressure signals, comprising a visual indicator responsive to the high pressure signal for providing a high pressure visual indication, a visual indicator responsive to the low pressure signal for providing a low pressure visual indication, a system normal visual indicator which is normally maintained in an "on" condition, an audible alarm, circuit means responsive to either of the high or low pressure signals for turning off the system normal visual indicator and for activating the audible alarm, and a manual switch for deactivating the audible alarm.

Abstract: A fuel safety switch for the fuel system of a motor is designed to be placed in the fuel delivery system and includes a bellows responsive to the pressure of the fuel within the fuel system for expansion outwardly, coil springs disposed on both sides of the bellows to provide a snap action return of the bellows to a collapsed condition after a reduction in fuel pressure, a first set of contacts activating an over fuel indicator when the bellows is expanded beyond a predetermined limit, and a second set of contacts activating the motor brake retarders, if turned on, when the bellows collapses to the unexpanded state.

Abstract: An implement, preferrably a harrow having a row of soil working members mounted on upwardly extending shafts, has spraying nozzles for dispensing material on the ground adjacent the rear of the soil working members. The nozzles communicate with liquid material under pressure. The implement is coupled to a tractor and the operator of the tractor can monitor the material being sprayed by various devices in an electrical circuit that leads to the tractor. Wires are positioned to be bridged by the spray and indicator lights on the tractor dash board provide a visual signal when material is sprayed by each nozzle. Similarly, a micro switch or camera, or other actuation means can be located adjacent each nozzle to provide a signal for each nozzle spray. The nozzles communicate with an elongated pipe and the pipe is supported on the implement frame with adjusting means to change the direction of spray by the nozzles.