IF articles

The results of research activities performed

in a ten year period on the measurement of contact

forces are reported in this article. Activities firstly addressed

the fundamental properties of the state of strain

of 5 different railway wheel types. On this basis, simple

principles through which contact forces can be derived

from strain measurements were established (CML

method) and an instrumented wheelset for the measurement

of vertical and lateral contact forces Q and Y was developed.

With this wheelset, the Y force is measured continuously

and is corrected for variations of magnitude and

lateral position of the Q force. The measurement is practically

unaffected by signal drift and thus allows long-term

measurements without the need for zeroing the measurement

chain. The main disadvantages of wheel-based measurements

are thus eliminated, whereas all advantages are

retained: low effect of the inertia of the material between

contact zone and strain gauges; possibility to measure on

bogies with independently rotating wheels; possibility to

measure during traction and braking; relatively simple

measurement chain, data processing, calibration, zeroing,

all with a low number of acquisition channels.