Approximately 400 measurements, which is plenty for one day. The device can be recharged in 90 minutes.

We provide each tribometer with the appropriate power supply for the country it is being sent to, with the correct plug fitting as well.

Our default values are 200 mm/s speed, 3% slip and 100 N normal force (750 MPa contact stress)

The device can test 0.5-12 % slip , up to 200 N and up to 300 mm/s.

We would advise using our default conditions for most scenarios, these allow a comparison to our existing datasets.

Tribometer accuracy is difficult to put a number on. A portable rail tribometer creates a model wheel/rail system and measures the friction of this system. The accuracy of the measurement is determined by (1) how close the model system is to the real system of interest, (2) how well the model system can be controlled and (3) how accurately the force measurement can be taken.

To provide information (1) we have carried out back-to-back measurements with full scale wheel and rail test facilities. We use a higher contact pressure than most other portable tribometers, closer to the system of interest.

For (2) we have developed our test device to be as closely controlled as possible. This included a PID loop to maintain normal force even if there are corrugations or rail defects. Our magnetic clamps, as well as our operation of testing using an angled wheel, provides more closely-controlled conditions than push style tribometers. We also measure the angle of the wheel and normal force every 1mm during a test; this can be viewed in the results files.

We have carried out a lot of back measurements with full scale university test facilities with very comparable results. These have included friction coefficients of below 0.05 (lubricated/contaminated conditions) and up to 0.5 (dry/hot conditions).

 We are not aware of any large differences between our measured values and the real system when using this full scale rig.

If this was the case tribometer data would still be useful to provide indicative values of rail operation for our normal use cases of rail inspections and optimising friction management. 

Yes, slip can be changed via the configuration file. The device can be programmed to carry out consecutive tests at a range of slip values, or change slip during a test.

The angle of the wheel, relative to direction of travel, is how we generate slip and measure the normal and tangential force on the wheel. A 30mrad angle is equivalent to approximately 3% slip.

This is a thumb screw with a component that butts up against the gauge face. There is an arbitrary numbered system on the device. For example this would be set at position ‘2.5’ and kept consistent through testing.

The wheel can move approximately 5 mm in the vertical axis, normal force is maintained throughout testing via an actuator and a PID loop. This normal force (up to 200N) can be set by the user.

Using our system, normal force can be controlled even when rail is corugated.

We would advise calibration every 12-24 months but this is dependent on usage. The unit can be shipped back to our workshop where we can calibrate. The cost for this is £1050 including our return shipping from our workshop, we also include any relevant hardware and software maintenance.

No, it is a bearing steel. We originally used actual train wheel steel (ER8) but had consistency issues due to work hardening and oxidation. We have been through different iterations of wheel material and roughness.  We can provide technical drawings for the wheel and spares if you would like to change this or manufacture your own.

An interval would be 15 seconds but the wheel does not generally get hot in normal usage (<50 measurements)

Our bearing steel wheels use a hard material to reduce surface changes during usage

We have not seen any excessive wear after 10,000+ measurements. However, the wheel could be replaced if this becomes a problem. There is a single allen key used to change the wheel.