Electro-pneumatic tractor-trailer brake system

In an automotive tractor which comprises road-engaging wheels which are suspended from a powertrain-containing chassis to support the tractor for over-the-road travel and via at least certain of which the powertrain-containing chassis imparts automotive motion to the tractor, pneumatic-operated service brakes and spring-operated parking brakes for at least some of said wheels, a pneumatic power supply, a pneumatic circuit coupling said pneumatic power supply with said service brakes and parking brakes, said pneumatic circuit comprising one branch which extends from said pneumatic power supply, through a service brake control valve disposed for operation by the driver, to said service brakes such that operation of said service brake control valve is effective to operate said service brakes, and another branch extending from said pneumatic power supply to said parking brakes, said pneumatic circuit further comprising valve means for exercising control over pneumatic-operated service and spring-operated parking brakes for road-engaging wheels of a trailer when such a trailer is coupled to said tractor for hauling by said tractor and also over said parking brakes of said tractor, means coupling said valve means with said one branch such that the operation of the service brakes of such a trailer is slaved to the operation of said service brakes of said tractor via said valve means, and means coupling said valve means with said another branch such that the operation of said parking brakes of said tractor and the parking brakes of such a trailer is effected via said valve means from a control which is accessible to the driver for selective operation of said parking brakes of said tractor and the parking brakes of such a trailer, said valve means comprising a multi-port pneumatic valve through which the service and parking brakes of such a trailer are connected with said pneumatic circuit, said multi-port pneumatic valve comprising a control port to which a pneumatic control signal is applied for controlling operation of said multi-port pneumatic valve, the improvement which comprises said control comprising an electrical control for selectively operating said parking brakes of said tractor and the parking brakes of such a trailer, said electrical control comprising electrical command means for operation by the driver, electrical circuitry coupling said electrical command means to said valve means, said valve means including an electric-actuated valve means portion to which said electrical circuitry is connected such that said electric-actuated valve means portion is under the control of said electrical command means, said electric-actuated valve means portion being coupled with said control port of said multi-port pneumatic valve for controlling the application of the pneumatic control signal to said control port, said multi-port pneumatic valve comprising means for causing the parking brakes of such a trailer to be operated in response to the application of the pneumatic control signal to said control port by said electric-actuated valve means portion.

In an automotive tractor which comprises road-engaging wheels which are suspended from a powertrain-containing chassis to support the tractor for over-the-road travel and via at least certain of which the powertrain-containing chassis imparts automotive motion to the tractor, pneumatic-operated service brakes and spring-operated parking brakes for at least some of said wheels, a pneumatic power supply, a pneumatic circuit coupling said pneumatic power supply with said service and said parking brakes, said pneumatic circuit comprising one branch which extends from said pneumatic power supply, through a service brake control valve disposed for operating by a driver of the tractor, to said service brakes such that operation of said service brake control valve is effective to operate said service brakes, and another branch extending from said pneumatic power supply to said parking brakes, and a control which is accessible to the driver for operating said parking brakes, the improvement which comprises said control comprising a pressure transducer sensing pressure of compressed air in said pneumatic power supply and providing a sensed pressure signal, an electrical control device accessible to the driver for providing a command signal to command operation of said parking brakes, and an electronic control circuit comprising respective inputs which receive the respective signals from said pressure transducer and said control device and an output which is coupled to said parking brakes and via which control of said parking brakes is exercised, said electronic control circuit comprising means for causing said parking brakes to be operated when the command signal is given by said device, and means for causing said parking brakes to be operated when the sensed pressure signal drops below a certain threshold, in which said parking brakes are coupled to said pneumatic power supply through an electric-actuated pneumatic valve which has an electrical control input connected to said output of said electronic circuit and is operated by said electronic control circuit to open and closed conditions to selectively conduct compressed air from said pneumatic power supply to said parking brakes, said parking brakes operating when said electric-actuated pneumatic valve is closed, in which said electrical control device is an electro-mechanical device which comprises an electric switch which provides the command signal calling for parking brake operation when the switch is not actuated, a spring-biased operator, and an electro-magnet and which is organized and arranged to bias the operator away from actuation of the switch thereby biasing the operator toward commanding parking brake operation, but in response to activation of the operator by the driver, to cause the switch to be actuated by the operator and to be held actuated by said electro-magnet against the spring bias so long as the sensed pressure signal exceeds that certain threshold, but when the sensed pressure signal from said pressure transducer drops below that certain threshold, the spring bias is effective to move the operator away from actuation of the switch and call for parking brake operation.

In a tractor-trailer combination wherein the trailer comprises road-engaging wheels, and the tractor comprises road-engaging wheels which are suspended from a powertrain-containing chassis to support the tractor for over-the-road travel and via at least certain of which the powertrain-containing chassis imparts automotive motion to the tractor, pneumatic-operated service brakes and spring-operated parking brakes for at least some of the wheels of the tractor-trailer combination, a pneumatic power supply, a pneumatic circuit coupling said pneumatic power supply with said service and said parking brakes, said pneumatic circuit comprising one branch which extends from said pneumatic power supply, through a service brake control valve disposed for operation by a driver of the tractor to said service brakes such that operation of said service brake control valve is effective to operate said service brakes, and another branch extending from said pneumatic power supply to said parking brakes, and a control which is accessible to the driver for operating said parking brakes, the improvement which comprises said control comprising a pressure transducer sensing pressure of compressed air in said pneumatic power supply and providing a sensed pressure signal, an electrical control device accessible to the driver for providing a command signal to command operation of said parking brakes, and an electronic control circuit comprising respective inputs which receive the respective signals from said pressure transducer and said control device and an output which is coupled to said parking brakes and via which control of said parking brakes is exercised, said electronic control circuit comprising means for causing said parking brakes to be operated when the command signal is given by said device, and means for causing said parking brakes to be operated when the sensed pressure signal drops below a certain threshold, in which said parking brakes are coupled to said pneumatic power supply through electric-actuated pneumatic valve means connected to said output of said electronic circuit and operated by said electronic control circuit to selectively conduct compressed air from said pneumatic power supply to said parking brakes, said parking brakes operating when said electric-actuated pneumatic valve means is not conducting compressed air from said pneumatic power supply to said parking brakes, in which said electrical control device comprises an electro-mechanical device which comprises an electric switch which provides the command signal calling for parking brake operation when the switch is not actuated, a spring-biased operator, and an electro-magnet and which is organized and arranged to bias the operator away from actuation of the switch thereby biasing the operator toward commanding parking brake operation, but in response to activation of the operator by the driver, to cause the switch to be actuated by the operator and to be held actuated by said electro-magnet against the spring bias so long as the sensed pressure signal exceeds that certain threshold, but when the sensed pressure signal from said pressure transducer drops below that certain threshold, the spring bias is effective to move the operator away from actuation of the switch and thereby call for parking brake operation, and said electronic control circuit couples said switch and electro-magnet such that in response to actuation of said switch by said operator, said switch is latched actuated by said electronic control circuit operating said electro-magnet, and the sensed pressure signal is effective via said electronic control circuit to unlatch said switch when the sensed pressure signal drops below that certain threshold, and said operator being operable by the driver for mechanically unlatching said switch at any time.

In a tractor-trailer combination wherein the trailer comprises road-engaging wheels, and the tractor comprises road-engaging wheels which are suspended from a powertrain-containing chassis to support the tractor for over-the-road travel and via at least certain of which the powertrain-containing chassis imparts automotive motion to the tractor, pneumatic-operated service brakes and spring-operated parking brakes for at least some of the wheels of the tractor-trailer combination, a pneumatic power supply, a pneumatic circuit coupling said pneumatic power supply with said service and said parking brakes, said pneumatic circuit comprising one branch which extends from said pneumatic power supply, through a service brake control valve disposed for operation by a driver of the tractor to said service brakes such that operation of said service brake control valve is effective to operate said service brakes, and another branch extending from said pneumatic power supply to said parking brakes, and a control which is accessible to the driver for operating said parking brakes, the improvement which comprises said control comprising a pressure transducer sensing pressure of compressed air in said pneumatic power supply and providing a sensed pressure signal, an electrical control device accessible to the driver for providing a command signal to command operation of said parking brakes, and an electronic control circuit comprising respective inputs which receive the respective signals from said pressure transducer and said control device and an output which is coupled to said parking brakes and via which control of said parking brakes is exercised, said electronic control circuit comprising means for causing said parking brakes to be operated when the command signal is given by said device, and means for causing said parking brakes to be operated when the sensed pressure signal drops below a certain threshold, in which said parking brakes are coupled to said pneumatic power supply through electric-actuated pneumatic valve means connected to said output of said electronic circuit and operated by said electronic control circuit to selectively conduct compressed air from said pneumatic power supply to said parking brakes, said parking brakes operating when said electric-actuated pneumatic valve means is not conducting compressed air from said pneumatic power supply to said parking brakes, in which at least one wheel of said tractor has such a parking brake and at least one wheel of said trailer has such a parking brake and such a service brake, and said control comprises two such control devices, one for controlling the operation of solely the parking brakes of said at least one trailer wheel and the other for controlling the operation of the parking brakes of both said at least one trailer wheel and of said at least one tractor wheel, and said electric-actuated pneumatic valve means comprises two separate electric-actuated pneumatic valves under the control of said two separate control devices such that said one of said two separate control devices controls only one of said two separate electric-actuated pneumatic valves but said other of said two separate control devices controls both said two separate electric-actuated pneumatic valves.

In an automotive tractor which comprises road-engaging wheels which are suspended from a powertrain-containing chassis to support the tractor for over-the-road travel and via at least certain of which the powertrain-containing chassis imparts automotive motion to the tractor, said tractor having service and parking brake systems including means providing for connection of service and parking brake systems for road-engaging wheels of a trailer with said tractor's service and parking brake systems when such a trailer is coupled to said tractor for hauling, said tractor comprising a service brake operator disposed for actuation by a driver of the tractor to operate the service brake systems of both said tractor and such a trailer, and parking brake operator means disposed for actuation by the driver to operate the parking brake systems of both said tractor and such a trailer, the improvement which comprises said parking brake operator means comprising a member which is arranged for displacement between first and second positions, an electric circuit element coacting with said member to distinguish between said member being in its first position and said member being in its second position, an electric circuit in which said electric circuit element is electrically connected, said electric circuit comprising means for giving a signal for commanding operation of at least one of the parking brake systems to apply it parking brakes when said electric circuit element indicates that said member is in other than its second position, a further electric circuit element which is disposed for coaction with said member, and which acts, via said electric circuit, to hold said member in its second position in response to the first-mentioned electric circuit element's indication that said member is in its second position, and means providing for the driver to override the holding action of said further electric circuit element on said member and cause said member to be displaced from its second position.