Multiple Brake Valves Patents (Class 303/8)
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Patent number: 11718281Abstract: A brake control system includes first and second brake control units for controlling braking of first and second bogies of a rail car. The brake control units include relay valves for controlling pressurized air flow from a main reservoir to brake cylinder pipes. A bypass conduit connects an outlet of a first brake control module to an outlet of a second brake control module. A fail-safe valve moves between open and closed positions. In the closed position, the fail-safe valve prevents a flow of the pressurized air between the brake control units. The fail-safe valve provides a first pilot pressure to a first relay valve upon a failure of the first brake control unit and provides a third pilot pressure to the second relay valve in response to a failure of the second brake control unit.Type: GrantFiled: November 1, 2021Date of Patent: August 8, 2023Assignee: FAIVELEY TRANSPORT RAIL TECHNOLOGIES INDIA PRIVATE LIMITEDInventor: Krishnakumar Sornamani
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Patent number: 11511716Abstract: A brake control signal amplification system that is designed to assist with the compliance to the FMVSS-121 Safety Standard for an air braked vehicle is described which comprises a trailer control module (TCM) that provides pneumatic signal to a trailer of the vehicle, a tractor protection valve (TPV) that protects a tractor air brake system in the event of a pneumatic disconnection from the trailer, and a pilot relay valve (PRV) coupled between the TCM and the TPV, wherein the PRV amplifies a control signal received from the TCM and delivers an amplified control signal to the to the TPV. The TPV delivers the amplified control signal to a control coupling for a trailer portion of a vehicle and delivers an air supply to a supply coupling for the trailer of the vehicle.Type: GrantFiled: June 12, 2019Date of Patent: November 29, 2022Assignee: BENDIX COMMERCIAL VEHICLE SYSTEMS LLCInventor: John V. Ripley
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Patent number: 9168900Abstract: An air brake monitoring system for monitoring a pressure of the system and providing various alarms and/or warnings to a user including tire and brake status/alarms and providing for a backup alarm. The air brake monitoring system configurable to function with the existing wiring of the vehicle and including an air brake monitoring device to be positioned in the vicinity of a brake valve. The air brake monitoring system is further provided to monitor the electrical stoplight power transmitted to the ABS brakes as well as the vehicle static/dynamic condition.Type: GrantFiled: June 6, 2012Date of Patent: October 27, 2015Assignee: Haldex Brake CorporationInventors: James L. Greene, David G. Engelbert, Jerry J. Donovan, Thomas D. Mullikin
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Publication number: 20150061359Abstract: The braking installation (1) comprises a pneumatic brake pipe (BP) which extends along the train, and wherein the pressure is controlled by a braking control apparatus (BCA) in the locomotive (L), an electrical power supply and communication line (EL) which extends along the train, and which is coupled to an electronic control unit (ECU) in the locomotive (L); and in each wagon (W) or in each group of wagons (W) associated with each other, an electronic module (EM) coupled to the electrical line (EL) through power supply and communication interface devices (I, I1), and further connected to an electro-pneumatic control assembly (EPC) designed for driving pneumatic brake valve means (ELV).Type: ApplicationFiled: March 15, 2013Publication date: March 5, 2015Applicant: FAIVELEY TRANSPORT ITALIA S. P. A.Inventors: Angelo Grasso, Francesco Demaria, David Wynd
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Publication number: 20150015060Abstract: The present application relates to a braking system for a train that is configured to operate in combination with pneumatic systems. The braking system includes an electronic control board and an electronic control valve coupled to the brake pipe on a railcar. The braking system is located on one of a number of railcars dispersed throughout the train. The electronic control board monitors a brake signal from the locomotive and selectively transmits signal data to the electronic control valve to release air pressure within the brake pipe. The braking system provides one or more air release locations within the brake pipe so as to reduce braking stresses.Type: ApplicationFiled: June 27, 2014Publication date: January 15, 2015Inventors: Jeffrey Scott Tippey, Amanda Tippey, Darold Tippey
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Patent number: 8789668Abstract: The invention concerns a master cylinder assembly (10, 110) for balancing the braking of a couple of wheels (LBW, RBW) of a vehicle. Each master cylinder (12) has a hollow body (14), a piston (15) and a chamber (16) suitable for containing a fluid having a primary control pressure depending on a driving force applied on the piston (15) and intended to be transmitted to a utilizing device (LBB, RBB). The assembly further includes a balancing duct (58) into which the chambers (16) come out, and a plurality of normally closed balancing valves (60).Type: GrantFiled: July 13, 2010Date of Patent: July 29, 2014Assignee: Vhit S.p.A.Inventors: Luigi Alberti, Leonardo Cadeddu
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Publication number: 20140174316Abstract: A brake control system for a consist having multiple cars is disclosed. The brake control system may include a conduit configured to direct a compressed fluid to the multiple cars, and a plurality of brakes, including at least one brake located at each of the multiple cars. The brake control system may further include a plurality of valves, including at least one valve located at each of the multiple cars and fluidly connected between the conduit and the at least one brake, and a main controller. The main controller may be configured to transmit a signal indicative of desired braking to each of the plurality of valves, causing substantially simultaneous activation of the plurality of brakes.Type: ApplicationFiled: December 20, 2012Publication date: June 26, 2014Applicant: EMDInventors: Dale Alexander Brown, Harinder Singh Lamba
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Publication number: 20130175852Abstract: A device for controlling braking in vehicles with two braking pedals (PS, PD), such as farm tractors, earthmovers and the like, comprises a body (30) in which there are formed: a pair of master cylinders (12S, 12D) with an associated brake booster (13S, 13D); a duct (18) for balancing braking of the rear wheels; seats (4, 5, 6) for a pair of balancing valves (14), a trailer brake valve (15) and a valve (16) for disabling braking of the front wheels; as well as passages (36, 46, 47, 62, 72) for transmitting a control pressure from the master cylinders to the valves and from the valves to outlets from the device (1) connected to the braking systems of the wheels of the vehicle and of a trailer, if any.Type: ApplicationFiled: September 14, 2011Publication date: July 11, 2013Applicant: VHIT S.P.A.Inventor: Leonardo Cadeddu
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Patent number: 8352142Abstract: A brake control apparatus includes: a master cylinder; a wheel cylinder; a hydraulic pressure source; a control valve arranged to increase or reduce the pressure of the wheel cylinder; an outside gate valve arranged to connect or disconnect between the master cylinder and the wheel cylinder; a brake operation sensing section configured to sense a driver's brake operation; and a control unit configured to control the hydraulic pressure source, the control valve, and the outside gate valve, to perform an automatic-brake pressure-increasing control to control the outside gate valve in a valve closing direction, to drive the hydraulic pressure source, and thereby to increase the pressure of the wheel cylinder in accordance with a vehicle condition, and to increase a driving quantity of the hydraulic pressure source when the brake operation is sensed during the automatic-brake pressure-increasing control.Type: GrantFiled: June 18, 2009Date of Patent: January 8, 2013Assignee: Hitachi, Ltd.Inventor: Shinichiro Nishida
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Patent number: 8297716Abstract: A hand brake control system for a rail vehicle hand brake having a release trigger. The system includes a cylinder for activating the release trigger of the hand brake and a source of pressure. A first valve selectively connects either the source of pressure at a first input or a second input to the cylinder at an output. A second valve selectively connects either the source of pressure or exhaust to the second input of the first valve at the output of the second valve. The first valve is a manually operated valve and the second valve is an electro-pneumatic valve. Linkage allows actuation of the first valve from at least two location about the vehicle.Type: GrantFiled: July 13, 2009Date of Patent: October 30, 2012Assignee: New York Air Brake CorporationInventors: Laurence E. Vaughn, Steven R. Newton, Derick Call
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Patent number: 8197013Abstract: In a brake system for a railway vehicle, actuation of the respective inlet, (4,6), exhaust (5,7) and a link valve (9) is controlled by an electronic control unit (20). The electronic control unit (20) has a counter for counting the number of valve operations performed by each respective inlet (4,6) and exhaust (5,7) valve, wherein the electronic control unit (20), in use, determines which of the respective inlet (4,6) and exhaust (5,7) valves are to be actuated to brake the railway vehicle. The determination is made at least in part in dependence on the number of valve operations performed by the respective inlet (4,6) and exhaust (5,7) valves.Type: GrantFiled: May 10, 2004Date of Patent: June 12, 2012Assignee: Knorr-Bremse Rail Systems (UK) LimitedInventors: Ross Bradley, Derek Tate, Rodney Miflin
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Patent number: 7866266Abstract: A magnetic levitation railways has at least one vehicle, a compressed air supply unit provided in the vehicle and at least one consumer connection line, the compressed air supply unit has at least two compressed air lines laid in the vehicle and connected to at least one compressed air source each, and the consumer connection line can be connected to one another of the compressed air lines.Type: GrantFiled: March 10, 2005Date of Patent: January 11, 2011Assignee: ThyssenKrupp Transrapid GmbHInventors: Axel Hempelmann, Siegbert Kunz
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Publication number: 20100304929Abstract: A braking system and method provided for a utility vehicle pneumatically coupled to a trailer. The system has an electronic control unit, a valve device that can be electrically connected by the at least one electronic control unit, the valve device building up pressure for the trailer braking system when connected, causing the trailer to brake, and a pressure sensor which detects the pressure for the trailer braking system and transmits a corresponding signal to the electronic control unit. The electronic control unit can influence the pressure generated for the trailer braking system by pulsed connection of the valve device, taking into account the pressure detected by the pressure sensor for the trailer braking system.Type: ApplicationFiled: May 16, 2008Publication date: December 2, 2010Inventor: Eduard Hilberer
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Publication number: 20100106385Abstract: Methods and valve arrangements for controlling the flow of pressurized air from a tractor to a trailer reservoir and to a trailer spring brake chamber. In one exemplary embodiment, pressurized air from a tractor is supplied from a tractor to the trailer reservoir and to the trailer spring brake in different filling modes based on a user input. In another exemplary embodiment, pressurized service air is used to charge or partially charge the trailer reservoir.Type: ApplicationFiled: October 29, 2008Publication date: April 29, 2010Applicant: BENDIX COMMERICAL VEHICLE SYSTEMS LLCInventors: Travis G. Ramler, Richard Conklin
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Publication number: 20090302674Abstract: A towing arrangement on a vehicle includes a pair of glad hands for receiving pressurized air and a plurality of double check valves connecting the glad hands to valves associated with a braking system of the vehicle. Air from a first glad hand is supplied through a first of the double check valves to a spring brake modulating relay valve associated with spring brakes of the vehicle. Air from a second glad hand is supplied through a second of the double check valves to a first release valve associated with service brakes of a front axle of the vehicle and through a third of the double check valves to a second release valve associated with service brakes of a rear axle of the vehicle.Type: ApplicationFiled: June 9, 2008Publication date: December 10, 2009Inventors: Keith Alan Hurlburt, David Robert Jeffery
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Publication number: 20090218879Abstract: A train including a brake pipe (14) and an electrical train line (50) extending from at least one locomotive through at least first and second cars which are adjacent to each other, the first and second cars each include a brake cylinder, reservoir and a brake valve The first car includes an electro-pneumatic brake valve which is responsive to electric signals on the train line to produce a first car pneumatic apply brake signal from the first reservoir and release brake signal for the first brake cylinder and the brake signal pipe (33) The first car also includes a first valve (31) to transmit the first brake signals to the brake signal pipe and to isolate the connection to the brake signal pipe for a breakaway at one of the cars The second car includes a pneumatic brake control valve which is responsive to the first car pneumatic brake signals on the brake signal pipe and brake pipe pressure m the brake pipe to produce a second car pneumatic apply and release brake signals for the second brake cylinder corrType: ApplicationFiled: February 3, 2006Publication date: September 3, 2009Inventors: James R. Truglio, Bryan McLaughlin, Lawrence E. Vaughn, Vincent S. Guarrera, JR., Eric Wright
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Patent number: 7513576Abstract: An air treatment system and method are provided for supplying a brake system of a utility vehicle with compressed air. The air treatment system includes a compressed air outlet that is used for feeding a parking brake system, more specifically for ventilating at least one spring-loaded cylinder of a parking brake and thus for releasing the parking brake. An electrically actuated valve, by which the compressed air outlet can be prevented from being supplied with compressed air, is provided, along with an indicator that can be electrically evaluated to determine if a person is present for driving the vehicle. The electrically actuated valve prevents the compressed air outlet from being supplied with compressed air when the indicator is not provided.Type: GrantFiled: March 10, 2006Date of Patent: April 7, 2009Assignee: Knorr-Bremse Systeme fuer Nutzfahrzeuge GmbHInventor: Eduard Hilberer
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Publication number: 20080252138Abstract: A magnetic levitation railways is described comprising at least one vehicle (1, 2), a compressed air supply unit provided in the vehicle (1, 2) and at least one consumer connection line (5, 15). According to the invention said compressed air supply unit has at least two compressed air lines (3, 4, 12, 14) laid in said vehicle (1, 2) and connected to at least one compressed air source (e.g. 19 to 22) each. The consumer connection line (5, 15) can be connected to one or another of the compressed air lines (3, 4, 12, 14).Type: ApplicationFiled: March 10, 2005Publication date: October 16, 2008Inventors: Axel Hempelmann, Siegbert Kunz
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Patent number: 7014275Abstract: In a hand brake control system for a hand brake on a railway vehicle, a sensor detects if a spool in a fluid pressure force regulating valve of the hand brake control system is in a first position to ensure that such hand brake has been applied after an apply-hand-brake procedure has been completed.Type: GrantFiled: December 18, 2003Date of Patent: March 21, 2006Assignee: Westinghouse Air Brake Technologies CorporationInventor: Michael E. Ring
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Patent number: 6578679Abstract: The invention relates to a brake system for railway equipment. More particularly, the invention relates to brake devices and systems for pneumatically and manually actuating such devices on railroad train cars such as freight cars. The brake system can be integrated into modern trains without interfering with existing air brake systems. The brake system can be remotely operated, locally pneumatically operated and/or locally manually operated. Monitoring equipment for determining the status of the brakes from remote and local positions may also be provided. The invention may be configured to fit within the envelope of prior art handbrake systems.Type: GrantFiled: April 4, 2001Date of Patent: June 17, 2003Assignee: UTD IncorporatedInventors: John L. Hill, Donald B. Harris, Joram Shenhar
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Patent number: 6491352Abstract: An integral intermodal train is provided for carrying standard over-the-highway semi-trailers. Each segment can have a plurality of platforms and may be loaded or unloaded independently of any other segment using a self contained, roll-on/roll-off system. Several sub-systems to speed performance and enhance reliability, such as an electronic assisted air brake, health monitoring, trailer tie-down and locomotive interface subsystems, can be provided on each segment. A spring applied parking brake is provided for the segments and operably connected to the train pneumatic brake systems. In a preferred embodiment the brake is automatically applied when brake pipe pressure falls below 40 psi nominal. The pneumatic valving for the parking brake prevents application of the valve in an emergency braking situation, until the pressure has bled off in normal system leakage, preventing wheel damage. A handle is provided for manual application and release of the parking brake when desired.Type: GrantFiled: March 15, 2001Date of Patent: December 10, 2002Assignee: Westinghouse Air Brake Technologies CorporationInventor: Thomas Engle
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Patent number: 6394559Abstract: A control apparatus is provided which is engageable with a hand brake assembly on a railway vehicle for operation of an application cylinder for applying the hand brake assembly. This apparatus includes a source of fluid pressure which is engageable with the railway vehicle. A pneumatic actuation valve which is connected to the source of fluid pressure for initiating communication of fluid pressure from the source of fluid pressure. A force regulating valve which is connected to the pneumatic actuation valve for receiving the fluid pressure from the actuation valve and a mechanically driven valve is connected to the force regulating valve for receiving the fluid pressure from the force regulating valve and for communicating the fluid pressure to the application cylinder to apply the hand brake assembly.Type: GrantFiled: September 15, 2000Date of Patent: May 28, 2002Assignee: Westinghouse Air Brake Technologies CorporationInventors: Michael E. Ring, Ronald Henry, James E. Hart
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Patent number: 6276761Abstract: An air braking system of a vehicle has a compressor, non-return valve, manifold, electrically actuable demand valve, an air consumer circuit. An auxiliary circuit connects the manifold to the consumer circuit via an electrically actuable valve and non-return valve. In the event of electrical failure air under pressure can be supplied to the consumer circuit via the auxiliary circuit. In another aspect a plurality of consumer circuits are provided. These circuits may be charged from the compressor via the manifold, or interconnected via the manifold independently of the compressor. This arrangement permits more flexible compressor operation and/or a greater reserve in the event of failure of the pressure source.Type: GrantFiled: October 21, 1999Date of Patent: August 21, 2001Assignee: Wabco Automotive UK LimitedInventor: Andrew Howard Beck
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Patent number: 6179391Abstract: A braking system is able to meet emergency stopping distance requirements associated with a failed rear axle service control line by modifying the service relay valve. The service relay valve incorporates a biased double check valve so that an additional or secondary control line from the foot control valve communicates with the service port of the relay valve. If the primary circuit is operational, a biasing force imposed on the double check valve permits normal operation via the primary service line. On the other hand, if the primary service line is lost, the biasing force is overcome and communication between the secondary service line and the service port of the relay valve is established.Type: GrantFiled: February 1, 1999Date of Patent: January 30, 2001Assignee: AllliedSignal Truck Brake Systems CompanyInventors: Charles E. Eberling, Gary R. Hendershot, John J. Kemer, Andrew Marsh, Richard T. Ross, Chris G. Swansegar
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Patent number: 5456526Abstract: A wheel lock prevention system prevents locking of wheels in a vehicle including a front axle having right and left front wheels, a first rear axle having right and left driving wheels, and a second rear axle having right and left follower wheels. A control part determines that locking or skidding of particular wheels may occur based on signals from sensors. In response, the control part transmits a signal to apply the appropriate brake force to the appropriate wheels.Type: GrantFiled: November 26, 1993Date of Patent: October 10, 1995Assignee: Akebono Brake Industry Co., Ltd.Inventors: Yoshihisa Iwasa, Shigeki Tsuchiya, Katsuya Miyake
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Patent number: 5383717Abstract: A brake control mechanism allows the engineman in a lead locomotive to control the brakes of a helper locomotive and does not require a manual connection of the brake pipe of the train to that of the helper locomotive. The End of Train (EOT) unit is used to effect this control. The EOT transmits brake pipe pressure data sensed at the end of the train. Both the lead locomotive and the helper locomotive are equipped with Head of Train (HOT) units which receive the transmitted data from the EOT unit. In the case of the HOT unit in the lead locomotive, this data is processed and displayed for the engineman in that locomotive, as is the normal operation in those units. However, in the case of the HOT unit in the helper locomotive, that unit is first of all set to receive the transmitted data from the EOT unit by dialing in the identification (ID) of the EOT unit using thumbwheels on the HOT unit provided for that purpose.Type: GrantFiled: September 10, 1993Date of Patent: January 24, 1995Assignee: Pulse ElectronicsInventors: Emilio A. Fernandez, Angel P. Bezos
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Patent number: 5372413Abstract: A vehicle braking system has a controller responsive to wheel speed signals for sensing skid conditions of the wheels and for generating skid control instructions. A primary fluid pressure supply includes a fluid pressure source and a fluid pressure reservoir and wheel brakes are responsive to brake pressure supplied to the brakes by supply valves, each of which is adapted to supply fluid brake pressure to a different wheel brake or brakes from the primary supply in accordance with a brake operating signal which can be modulated by skid control units. Each pair of supply valve and skid control unit is adapted to control the fluid pressure of a different wheel brake or brakes. A plurality of brake operating signals are generated, independently of the skid control units, as a function of a brake command signal and a brake operating signal is supplied for each of the supply valves. All the components are connected together so as to be mountable on the vehicle as a discrete unit.Type: GrantFiled: August 27, 1992Date of Patent: December 13, 1994Assignee: Grau LimitedInventors: William S. Broome, Colin F. Ross
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Patent number: 5226692Abstract: A limited service application of the service brakes of the trailer portion of a tractor trailer combination vehicle is applied and held while the vehicle operator gets out of the cab to make a pre-trip inspection. The service actuation is initiated by releasing the trailer parking brakes while the tractor parking brakes remain applied and then making a momentary service brake actuation by use of the vehicle dual control valve. A control valve assembly responds to the service actuation to hold a service actuation of the trailer brakes until either the tractor parking brakes are released or the trailer parking brakes are applied.Type: GrantFiled: September 26, 1991Date of Patent: July 13, 1993Assignee: Allied-Signal Inc.Inventor: Charles E. Eberling
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Patent number: 5172960Abstract: A braking system for a vehicle having wheels provided with braking devices, the system causing carbon brakes to wear less than do conventional systems.Type: GrantFiled: February 7, 1992Date of Patent: December 22, 1992Assignee: Aerospatiale Societe Nationale IndustrielleInventor: Jean-Louis Chareire
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Patent number: 4798419Abstract: An anti-jackknifing valve is designed for use with tractor trailers and is operably inserted in the hydraulic fluid brake line of such vehicles. The valve prevents jackknifing of a trailer during brake applications by initially actuating the brakes on the trailer. The valve arrangement directs hydraulic brake fluid to the trailer brakes first, and a continuing movement of the valve piston then permits hydraulic brake fluid to be delivered to the tractor brakes to thus substantially eliminate the risk of jackknifing.Type: GrantFiled: July 27, 1987Date of Patent: January 17, 1989Inventor: William E. Barnes
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Patent number: 4763958Abstract: Apparatus for matching the brake pressure of vehicle combinations to the actual load comprising tranducers (36, 41) for adjusting the brake pressure of the units (10, 13) included in the vehicle combination, in dependence on pulling and pushing, respectively, of a coupling between the tractor vehicle and the trailer vehicle and in dependence on the loading of the vehicles.Type: GrantFiled: June 16, 1986Date of Patent: August 16, 1988Assignee: VBG Produkter ABInventor: Stephan N. A. Ohrgard
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Patent number: 4653812Abstract: A railway car has a brake control equipment group on each truck for governing the brakes thereof including simplified light weight triple valve and reservoir equipment and a modulation equipment group is disposed between trucks of the car providing normal per car requirements for modulating pressure in the brake pipe that would normally be provided by a conventional ABD valve required for each truck equipment group.Type: GrantFiled: September 16, 1985Date of Patent: March 31, 1987Assignee: General Signal CorporationInventor: Thomas H. Engle
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Patent number: 4629256Abstract: A fluid pressure braking system for a tractor-trailer vehicle in which the braking system of the tractor is connected to the braking system of the trailer through trailer control and trailer supply lines includes a relay valve which controls communication between service reservoirs on the tractor and the trailer control line in response to operation of the vehicle brake valve. Use of the relay valve to control the communication to the trailer control line permits greater volumes of air to be supplied to the trailer control line, thereby appreciably reducing transmission times of brake application signals.Type: GrantFiled: May 6, 1985Date of Patent: December 16, 1986Assignee: Allied CorporationInventor: Richard C. Fannin
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Patent number: 4509801Abstract: A fluid pressure brake control system of the direct release type for a freight locomotive comprises a first pipe bracket having a manually controllable automatic brake valve device connected thereto on one side for governing fluid brake control pressure in a train pipe, and a manually controllable independent brake valve device is connected on another side of the bracket for governing brakes of the locomotive independent of brakes of freight cars in a train. There is a locomotive brake control valve device comprising a second pipe bracket having a service valve portion secured to one side thereof corresponding to a service valve portion such as is conventionally used on freight car control valve devices. A quick release and emergency valve portion is secured to another side of the second pipe bracket for governing emergency brake pressure and for governing independent direct release of brakes of a locomotive in response to actuation of the manually controllable independent brake valve device.Type: GrantFiled: November 18, 1983Date of Patent: April 9, 1985Assignee: General Signal CorporationInventors: Ronald O. Newton, Eric Wright
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Patent number: 4354713Abstract: The invention relates to a service brake system for towed vehicles and particularly to a service brake system for double trailer combinations and a metering relay valve therefor. According to the invention, a variable reaction amplifying relay valve, controlled by service brake control line pressure, meters reservoir pressure from the leading trailer to the service brake control line in the trailing trailer. Below a predetermined pressure, the metering relay valve provides an amplified pressure output relative to input. Above this predetermined point, the output pressure is substantially one-to-one.Type: GrantFiled: November 13, 1980Date of Patent: October 19, 1982Assignee: Echlin Inc.Inventor: Norman Edwards
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Patent number: 4178044Abstract: A brake mechanism for a tractor comprising an air tank containing compressed air, a brake valve connected to said air tank, a brake pedal operatively connected to said brake valve, a pair of solenoid operated selector valves, a pair of throttle valves each being connected to said one of the selector valves, respectively, a pair of double check valves each being connected to said one of the selector valves at one end thereof, the other end of which being connected to said one of the throttle valves, respectively, two pairs of brake chambers each being connected to one of said double check valves, respectively, and a switch connected to said selector valves.Type: GrantFiled: July 13, 1978Date of Patent: December 11, 1979Assignee: Kabushiki Kaisha Komatsu SeisakushoInventors: Yuzuru Itoh, Masaaki Ichimura, Masaru Uenoyama