TEST INSTRUMENTATION - REPORT NO. 10

THE IMPORTANT MEASURING DEVICES AND TEST INSTRUMENTATION SYSTEMS USED IN TESTING AND EVALUATING VARIOUS COMPONENTS OF RAPID TRANSIT HARDWARE TO DETERMINE THE OPTIMUM OPERATING EQUIPMENT FOR USE IN THE BARTD SYSTEM ARE DESCRIBED. IT IS SUGGESTED THAT A MULTICHANNEL, DIRECT-WRITING, LIGHT-BEAM OSCILLOGRAPH BE USED FOR INSTRUMENTATION RECORDING FOR TRANSIT SYSTEM CAR TESTS, SINCE IT IS MORE FLEXIBLE AND CONVENIENT THAN MAGNETIC TAPE. THE IDEAL LIGHT-BEAM RECORDER, WHICH DOES NOT YET EXIST, WOULD BE LIGHTWEIGHT AND HAVE AT LEAST SEVEN ANALOG CHANNELS AND FIVE EVENT CHANNELS. THE RECORDER SHOULD HAVE A WIDE SELECTION OF GALVANOMETERS, AND THE RECORDING PAPER SHOULD BE WIDE AND HAVE GRID LINES WITH AT LEAST 0.5-INCH INTERVALS. OTHER CRITERIA FOR THE ULTIMATE IN LIGHT-BEAM OSCILLOGRAPHS ARE LISTED. AN ACCELEROMETER SYSTEM FOR WIDE MEASUREMENTS SHOULD UTILIZE A RUGGED STRAIN-GAGE ACCELEROMETER WHICH HAS AS SMALL A RANGE AS POSSIBLE CONSISTENT WITH MAXIMUM LEVELS TO BE RECORDED. THE SYSTEM SHOULD ALSO INCLUDE A RECORDER WITH A 6--12 HZ, FLAT-RESPONSE GALVANOMETER AND A FILTER WITH RESPONSE CONSISTENT WITH THE GALVANOMETER. THE ROTARY POTENTIOMETER, THOUGH IN NEED OF SOME MODIFICATION, IS PRESENTLY BETTER SUITED TO MOTION MEASUREMENTS ON VEHICLE SUSPENSION THAN A STRAIN-GAGE CANTILEVER SPRING, LINEAR POTENTIOMETERS, OR DC TO DC LINEAR VARIABLES DIFFERENTIAL TRANSFORMERS. THE ROTARY POTENTIOMETER IS CABLE-OPERATED AND IS EQUIPPED WITH A FILM- TYPE INFINITE-RESOLUTION ELEMENT. IN THE CONSTRUCTION OF A NINTH WHEEL SYSTEM, STRESS IS LAID ON HIGH QUALITY AND BALANCE. ALSO, IN ORDER THAT THE WHEEL OPERATE VERY FREELY, THE MOUNTING OF THE WHEEL WITH GENERATOR AND CONTACTS MUST BE ACURATE, SINCE THE PRECISENESS OF THE SYSTEM DEPENDS ON A LARGE RATIO BETWEEN THE INERTIA OF THE WHEEL AND THE FORCE NECESSARY TO TURN IT. UNLESS IT IS NECESSARY TO DRIVE SEVERAL INDICATORS AT ONCE, A DC TACHOGENERATOR SHOULD BE AVOIDED. THE NINTH WHEEL, WHEN USED IN CONJUNCTION WITH A MULTICHANNEL LIGHT-BEAM RECORDER, PROVIDES AN EXTREMELY USEFUL INSTRUMENTATION SYSTEM. THE IMPORTANT FEATURE OF SUPPORT EQUIPMENT, SUCH AS CALIBRATION AND STANDARD INSTRUMENTS IS DURABILITY. BEACUSE OF THE ROUGH TREATMENT TO WHICH MOST SUPPORT EQUIPMENT IS SUBJECTED, THE INSTRUMENTS SHOULD BE AS RUGGED AS POSSIBLE, AND SHOCKMOUNTED IF PRACTICAL. /UMTA/

  • Supplemental Notes:
    • PROJ NO CAL-MTD-2
  • Corporate Authors:

    Parsons, Brinckerhoff-Tudor-Bechtel

    814 Mission Street
    San Francisco, CA  United States  94103
  • Publication Date: 1968

Subject/Index Terms

Filing Info

  • Accession Number: 00241769
  • Record Type: Publication
  • Source Agency: Urban Mass Transportation Administration
  • Files: TRIS, USDOT
  • Created Date: Oct 23 1981 12:00AM