Lothian Region Transport are one of the largest public transport companies in the UK. They run a fleet of coaches and double-decker buses that are used not only in the Lothian region of Scotland but also in many of England’s historic cities, including York and Cambridge.
As part of a standard maintenance programme, all their vehicles are routinely tested on a rolling road to check performance characteristics. Although this has allowed LRT to identify some problems with their vehicles, there were still areas in which improvements could be made. After much searching, LRT found that only Prodigy’s facilities could match their requirements.
LRT’s fleet of vehicles spans 30 years and on one day a member of staff could be driving a brand new coach whilst on the next it is an old double decker bus. A significant proportion of workshop time was being spent chasing problems that didn’t exist because the drivers were reporting faults with vehicles that were in fact just characteristics of their age.
Prodigy provides LRT with the means of determining a “signature map” for a new or fully functioning vehicle. Whenever a fault is reported, the vehicle is retested and compared to the good signature, allowing LRT’s mechanics to identify real rather than phantom problems. This has yielded significant savings through reduced vehicle repair times.
Automatic Test Control
Running vehicles on the rolling road was a manual activity which was very time consuming. The automation of this process included using a throttle actuator so that a driver wasn’t needed, and a dynamometer braking system to apply load to the vehicle. An interface was also made into the automatic gearboxes so that gear selection could be controlled.
Prodigy’s test schedules allow throttle position, dynamometer loading and gear selection to be controlled during an automatic test. A variety of control modes are also used so that tests can be performed with: fixed throttle positions; fixed loads; engine speed being controlled by adjustments in throttle position or load; and gear selection being made through adjustments in load.
Using Prodigy’s automatic sequence definition software it is easy for LRT’s engineers to develop a suite of test programmes which exercise all aspects of the vehicles.
Automatic Data Logging
In the past, all test measurements were made manually. This led to inaccuracies both in the reading and recording of values, and also to time skewing errors because it took so long to take a full set of measurements.
Prodigy takes a new set of measurements every 1/10 second, thus eliminating the errors experienced under the manual system. Snap shot recording of this data means that the current values of all temperatures, linear analogue and digital signals can be stored to disk. This can be triggered manually, or as part of an automatic test schedule, leaving the test operator to concentrate on other functions.
Condition Based Monitoring
Some parameters, such as the thermostat opening temperature and the minimum battery voltage, occur at an instance in time and need to be continuously monitored for. Prodigy is configured to understand the particular conditions that need to be met for each of these parameters and will continually monitor for them.
The monitoring of particular parameters can be started and stopped both manually and as part of a predefined test sequence. Once the data has been acquired it will be logged into a header data section alongside the log data of the currently running test.
Data, based on manufacturers specifications of the various components, is also available in the vehicle’s history files to provide a comparison when first testing a vehicle.
Remote Data Access
LRT’s multiple sites in Edinburgh meant that it was very important for test results to be easily accessed by engineers in remote locations. Prodigy Interconnect gives them this capability. Not only are the final test results available as soon as a test is completed, but current signal measurements can be viewed, in real time, over LRT’s own local area network.
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