ABSTRACT
I. Introduction ...................................................................................................................... 424
A. Reasons for Testing.................................................................................................. 424
II. Common Transducers ...................................................................................................... 425
A. Displacement Transducers ....................................................................................... 425
B. Accelerometers......................................................................................................... 426
1. Piezoelectric Accelerometers ............................................................................ 427
2. Capacitive Accelerometers................................................................................ 429
C. Strain Gauges ........................................................................................................... 430
1. Bridge Circuits .................................................................................................. 432
D. Force-Measuring Wheelsets..................................................................................... 433
1. Measuring Lateral Forces between Wheelset and Axle Box ........................... 435
2. Measuring Lateral and Vertical Wheel-Rail Forces — The Axle Method .... 435
3. Measuring Lateral and Vertical Wheel-Rail Forces — Wheel Methods ....... 436
4. Compensation for Undesired Parasitic Effects ................................................. 437
E. Vehicle Speed and Position Measurement .............................................................. 438
1. The AC Tachogenerator.................................................................................... 438
2. Hall Effect Probes ............................................................................................. 439
3. Ground Speed Radar ......................................................................................... 439
4. Determining Vehicle Position........................................................................... 440
III. Test Equipment Configuration and Environment............................................................ 441
A. Transducer Positions on Vehicles............................................................................ 442
IV. Data Acquisition............................................................................................................... 443
V. Measurement of Wheel and Rail Profiles........................................................................ 445
VI. Track Geometry Recording ............................................................................................. 447
A. Manual Survey ......................................................................................................... 448
B. Track Geometry Trolley .......................................................................................... 449
C. Track Recording Vehicles ....................................................................................... 449
D. Chord Offset Measuring Systems ............................................................................ 451
VII. Examples of Vehicle Laboratory and Field Tests........................................................... 452
A. Static/Quasi-Static Tests .......................................................................................... 452
1. Wheel Unloading Test....................................................................................... 452
2. Bogie Rotational Resistance Test ..................................................................... 452
3. Sway Test .......................................................................................................... 454
4. Body Modes Tests............................................................................................. 455
B. Dynamic Tests.......................................................................................................... 455
References..................................................................................................................................... 456
An understanding of testing and instrumentation methods is essential to the accurate construction
and validation of railway vehicle dynamic models. The dynamics engineer may need to produce
specifications for test work, understand the applicability and limitations of data produced, and
manipulate test results to provide comparisons with modelling work. This chapter provides an
overview of the situations in which the engineer may require test data, together with an introduction
to common techniques and equipment used, both in the laboratory and for conducting vehicle
testing on-track. The examples given largely relate to vehicle testing which forms the most relevant
body of work for the vehicle dynamics engineer. However, dynamic simulation is increasingly used
in rail/track related investigations where many of the same techniques may be applied.
