Transcript
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SERVICE MANUAL
6006
SPEED CONTROL SYSTEM CHECK AND CALIBRATION INSTRUCTIONS FOR
CHICAGO, MILWAUKEE, ST. PAUL and PACIFIC RAILROAD COMPANY
May, 1975 A-75-1978.1
WESTINGHOUSE AIR BRAKE COMPANY UNION SWITCH & SIGNAL DIVISION Swissvale Post Office, Pittsburgh, Pa. 15218 An Ame.rican-Standard Company
TABLE OF CONTENTS Page
Section I
SYSTEM AND COMPOENTS OPERATION 1.1
SYSTEM OPERATIONS 1.1.1 1.1. 2 1.1. 3 1.1.4 1.1. 5
II
Velocity Meter Frequency Standard Speed Control Amplifier and Valve Control Speed Control Failure Check Radar Unit
CHECK AND CALIBRATION PROCEDURES
1-1 1-1 1-1 1-3 1-4 1-9 1-10 2-1
1.1
LIST OF EQUIPMENT
2-1
1.2
TEST PROCEDURES
2-1
i
LIST OF ILLUSTRATIONS Figure
Page
1-1
Control System, Block Diagram
1-2
1-2
Velocity Meter, Block Diagram
1-3
1-3
Frequency Standard, Block Diagram
1-4
1-4
Speed Control Amplifier Circuits
1-5
1-5
Actual Velocity vs. Requested Velocity
1-6
1-6
Derivative Amplifier, Exhaust Cycle
1-7
1-7
Derivative Amplifier, Intake Cycle
1-8
1-8
Speed Control Failure System, Block Diagram
1-10
2-1
Frequency Measuring Test Setup
2-2
ii
SECTION I SYSTEM AND COMPONENTS OPERATION 1.1
SYSTEM OPERATION
The retarder leaving velocity is determined by requested velocity inputs which come from the four weight class control potentiometers on the Speed Selection Panels, Cuts are automatically categorized into four weight classes by the weigh rail, that is, extra heavy, heavy, medium and light weights. The system automatically associates the correct weight classification with each cut of cars. The speed control system detects the approachina car and removes the speed control system from the check mode, applies the requested velocity to the speed control amplifier and initiates the radar unit to start monitoring the car's actual velocity. The radar output (a signal of 31.4 Hz per mile per hour) is applied to the velocity meter. The velocity meter converts the radar output to a Oto 10 volt output (0.4V = lMPH) that is applied to the speed control amplifier. The speed control amplifier compares the requested velocity to the actual velocity and energizes an air relay or an exhaust relay increasing or decreasing the air applied to the retarder to decrease the speed of the car or increase speed due to the retarder's downhill grade. The speed control amplifier includes a derivative circuit that anticipates increases or decreases in speed and applies a voltage which allows the retarder to apply or release pressure in advance of the actual need._ This prevents a car from alternately slowing down and picking up speed a~ i t would do if only instantaneous speed errors were corrected. The derivative amplifier develops a voltage proportional to the acceleration or deceleration. The output is proportional to both the instantaneous and anticipated differences between measured and requested car speed. The derivative circuit has four separate gain controls, one for each weight class of cars. The gain control for each weight class is selected by the external car weighing circuits.
1.1.1
Velocity Meter (Figure 1-2)
The velocity meter receives a varyinq audio frequency signal (0-784.7 Hz) from the RF unit and changes it to a positive DC output voltage (0 to +10 V) which is proportional to the velocity of the moving car.
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RETARDER
RADAR UNIT
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RETARDER AIR CONTROL VALVES
VELOCITY METER M)TE:
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= ACTUl'\L
VELOCITY = REQUESTED VELOCI TY = VELOCITY ERROR
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