Showing papers on "Dynamic braking published in 1973"

Brake and control therefor

Abstract: A spring applied, electrically released brake illustrated as applied to escalators wherein the braking apparatus applies a first braking force sufficient to provide a predetermined deceleration under no load conditions. After a time delay, a second braking force is applied which when combined with the first braking force is sufficient to provide said predetermined deceleration under full load conditions. In emergency situations, when a safety circuit is interrupted, both braking forces are applied simultaneously to produce minimum stopping time.

Dynamic braking of electric motors with thermistor braking circuit

Abstract: A motor system for energizing and deenergizing an electric motor and for dynamically braking the motor to a halt after deenergization. When the motor is turned off, a dynamic braking circuit is connected in series with the motor windings to assure generator action and to provide for dissipation of the kinetic energy of the motor. The braking circuit incorporates a thermistor through which braking currents flow. Because of its comparatively high resistance at ambient temperatures the thermistor opposes high surge currents at the initiation of braking, thereby reducing arcing at the motor brushes when the kinetic energy of the motor is highest. As the motor decelerates, the resistance of the thermistor reduces automatically because of self-heating, thereby maintaining large currents in the braking circuit to bring the motor quickly to a halt.

Adaptive braking system control wheel selection by velocity comparison

Abstract: An adaptive braking system in which the speed of each wheel on an axle is independently sensed but the braking pressure of both axle wheels is controlled during adaptive braking by a single brake pressure modulator. Performance information from the wheel having the higher speed is used to determine when brake pressure should be reduced. Performance information from the wheel having the lower speed is used to determine when the brake pressure should be subsequently increased. If the ratio of the speed of the low speed wheel with respect to the speed of the high speed wheel drops below a predetermined level, the wheel having the higher speed controls adaptive braking.

Electric vehicle propulsion system

Abstract: A plurality of electrical devices are coupled by circuit means, including switching contactors, in series in one switching mode, and in parallel in another switching mode for current flow sense in one of the devices in a reverse direction. The devices may be dynamoelectric machines, which may be separately excited, and one of which is coupled to a rotatable apparatus such as an inertial device adapted selectively to absorb and equivalently store mechanical power output from or to equivalently restore and furnish mechanical power input to the device to which it is coupled. The arrangement is advantageously utilized in an electrically motivated vehicle such as an electrical propulsion system for rapid transit cars or trains. Conveniently, the switching circuit may selectively couple the traction motors to the power supply conductors for regenerative braking or to conventional power absorbing brake resistors for dynamic braking.

Motion control system for direct current motors, particularly in sewing machine uses

Abstract: A motion control system for the direct current motor of a sewing machine wherein an external brake applies a retarding force to the motor and the sewing machine needle mechanism once the motor has reached a predetermined essentially stable level. Braking is controlled by monitoring the emf or current of the motor when it is in a dynamic braking mode and by initiating stabilized speed control of the motor when the emf or current obtains a predetermined level. The external brake thereafter is energized upon occurrence of a signal representing the arrival of the needle mechanism at a predetermined location in the needle cycle.

Road vehicle braking system incorporating wheel slide protection

Abstract: A road vehicle braking system with wheel slide protection has a sensor which produces an a.c. signal at a frequency dependent on the rotational speed of a vehicle wheel. This signal is fed by way of a frequency voltage converter to a differentiating circuit to produce an output dependent on the rotational deceleration of the wheel, this output then being used to release the brakes when the rotational deceleration exceeds a predetermined value. Monitoring apparatus is provided to test the sensor and in the event of a fault to prevent releasing of the brakes during a subsequent braking operation.

Dynamic braking control system

Abstract: A dynamic braking control system is provided for the angular positioning of a rotating device in a desired angular orientation. An encoder disc is mounted to rotate with the rotating device and a target area established at a predetermined location on the encoder disc. A logic circuit responds to determination of braking zone locations on the encoder disc for supplying dynamic braking signals to a drive motor employed for driving the rotating device. After the rotating device has stopped, the encoder disc is interrogated to determine whether the rotating device is in the predetermined angular orientation. If not, the rotating device is accelerated until the next braking zone is sensed.

Dynamic brake limiting system

Abstract: A system for limiting the braking effort of diesel electric locomotive traction motors used to dynamically brake the locomotive. The system includes braking grid current limitation and further includes a circuit which generates a signal related to the magnitude of the traction motor field current and a signal related to the braked grid resistance current. These signals are summed and when the sum exceeds a specified value, a signal is generated for effecting the decrease in the traction motor field current to limit the dynamic braking effort.

Dynamic braking control

Abstract: Dynamic braking of a dc motor is controlled by forming two electrical quantities representing a field current and an armature current or a rotational speed of the motor respectively and adding the two electrical quantities to each other. Then a field regulator controls the field current so as to maintain the sum of the two electrical quantities substantially constant.

Brake control apparatus for a blending braking system to reduce effects of relative braking response times

Abstract: Braking control apparatus for controlling a blend of electropneumatic braking and dynamic braking in response to a braking command signal is responsive to a signal indicative of the degree of electric braking for producing a control signal for the electropneumatic braking apparatus to cause it to supplement the electric braking to give braking as called for by the command signal and the apparatus being responsive to a changing electric braking effect for causing the control signal for the electropneumatic brake to change in an exaggerated manner to reduce the effects of relative time delays in the effectiveness of the electric braking and the electropneumatic braking in response to the command signal.

Apparatus for preventing railway wheel lock

Abstract: A braking system method and apparatus for the type having a controller regulating the degree of brake application, an air valve, a pressure source whose application is governed by the air valve and including a dynamic braking means having load means connected across the dynamic braking motors, a lock-out magnet determining the application of the fluid pressure and an air brake whose employment is governed by the lock-out magnet the improvement comprising a pressure switch communicating with the pressure in the air brake and set at a predetermined pressure level; coupling means located between the load and the dynamic braking means for disconnecting the load means; and a conductor connected between said pressure switch and said coupling means so that when the lock-out magnet fails to regulate the application of the fluid pressure brakes and the dynamic braking motors, at the predetermined pressure level said switch sends an electrical signal through said conductor causing said coupling means to disconnect the load means from the dynamic braking motors.

Failsafe system for energizing the capstan motor of a magnetic tape transport system

Abstract: To prevent the breakage of tape in a magnetic tape transport system in the event of a complete power failure during normal operation, it has been customary to mechanically or dynamically brake the supply and take-up reels as quickly as possible. If during a normal re-wind cycle a power failure should occur, braking of a high inertia supply reel with its drive motor cannot be achieved as quickly as the relatively low inertia capstan motor stops. A failsafe system is disclosed for generating a voltage varying according to the velocity of rotation of a reel of magnetic tape. The generated voltage is automatically coupled to a power dissipating means upon a power failure to achieve dynamic braking of the reel, and is further automatically coupled to a capstan motor to maintain the capstan motor energized and rotating until the reel of magnetic tape is brought to a stop.

Recent studies of tire braking performance

Abstract: The results from recent studies of some factors affecting tire braking and cornering performance are presented together with a discussion of the possible application of these results to the design of aircraft braking systems. The first part of the paper is concerned with steady-state braking, that is, results from tests conducted at a constant slip ratio or steering angle or both. The second part deals with cyclic braking tests, both single cycle, where brakes are applied at a constant rate until wheel lockup is achieved, and rapid cycling of the brakes under control of a currently operational antiskid system.

Roadbed on which electrically powered vehicles can be operated

Abstract: A system for controlling wheeled vehicles on a track. The system provides for simultaneous remote control of a number of vehicles which receive both power and control signals from conducting elements on a track so configured as to receive the signals from a remote controller. The system allows unlimited steerability of the vehicles, continuous and smooth speed control, and dynamic braking and reversing of the vehicles. A roadbed for use in the system is disclosed.

Apparatus for regulating brake control pressure

Abstract: Apparatus for use with vehicle electro-pneumatic brake systems, said apparatus being characterized by a friction-free self-lapping valve device responsive to opposing control forces reflecting the degree of electrical dynamic braking and the degree of fluid pressure controlling the pneumatic friction braking for automatically maintaining the called-for overall braking effect of the dynamic and friction braking combined, said valve device being operable responsively to variation of dynamic braking effort for automatically maintaining the called-for electro-pneumatic braking relationship by compensatingly varying the degree of delivery fluid pressure for the pneumatic braking system.

Device for controlling the braking fluid pressure in the hydraulic brake system of motor vehicles

Abstract: To provide stabilized braking of a motor vehicle through a minimized stopping distance, the braking pressure to be applied to the driving wheel of the vehicle is controlled by the use of a signal which is sufficiently reliably indicative of the actual cruising speed of the vehicle, wherein the signal is produced through detection of the circumferential speed of not only the driving wheel but the trailing or non-driven wheel so that the objectionable factors influencing the signal are minimized.