| Functional tests of railcar brake systemsMeasurement & Test of brake forces, system pressures as well as other measurement quantities
 overview The precise  and accurate determination of acting brake forces as well as additional  important quantities (i.e., pressures) of the brake system of railcars is of highest  importance. The safe transport of persons and goods is of utmost priority.  Besides a required test of the brake force system during commissioning such  measurement system assisted testing procedures should be carried out during or  after maintenance and retrofitting. Although brake systems in good working  conditions are the requirements for a safe railcar operation, unfortunately regular time  interval-based measurement systems supported checks are still the exception. The  typical approach of operational personal carrying out daily operational checks  such as a brake system test during standstill or an overall system with a drive  and brake approach are not sufficient. Many possible failure modes, especially  in system components are not discovered.  In addition a condition based maintenance is  not possible with these approaches. Furthermore, the more and more increasing  pressure for cost efficiency and cost reduction, leads to the  questionable practice of increasing the maintenance intervals. If this is  solely based on an increase of maintenance interval durations the evolution of  critical errors is only a matter of time. The overall safety level of the  operated railcar decreases and eventually devastating accidents could occur.  Nevertheless, an approach based on independent measurement systems can  eventually lead to a win-win situation. The possibility to determine important  brake system characteristics (i.e., individual force-time profiles or brake  system pressures) permits:
 
    a condition based monitoring is  possible whereby the time-of-life of the individual subsystem is determined and  only system components are exchanged which require it  an overall system safety level  increase, as a time-discrete monitoring of the system and its components is  carried out The measurement and test system  PRODAT BKM has been skillfully engineered in order to suite these requirements and  to help to make public and non-public railways safer. It has been used for many  years by PRODAT and its customers. The system supports a large number of  different railcar brake types (i.e., disk or block types) and follows a modular  system architecture concept. It either replaces the wear components or is  integrated in between the wheel and wear component. Acquired are not only directly  acquired data time series profiles of the individual acting forces (time-force-profiles) but also of important additional quantities, such as  different brake system circuit pressures. In addition customer specific  additional signals can be easily integrated into the system. All required  measurement data is viewed, saved, archived and gathered in a documenting  protocol. Customers can either buy the measurement system, rent a system or can  use PRODATs measurement services at the customer site. Application variantsThe typical  system configuration of the mobile brake force measurement system PRODAT BKM  include: 
  cable-based  brake force measurement & test system – PRODAT BKM C (‘cable’)wireless  brake force measurement & test system – PRODAT BKM W (‘wireless) Constructional  variants exist for different brake types and include: 
  air  brakes (‘block brake’)disc  brakescustomer specific brake types Customer options for a system  acquisition  Wireless brake force measurement & test system PRODAT BKM-W The  measurement & test system PRODAT BKM-W permits the wireless determination  of important brake force system quantities of railcars, such as the acting  forces or pressure in the hydraulic brake circuits. If used the number of  detectable brake system failure modes is greatly increased, as also individual  subsystem functionality can be tested by using an independent and external  measurement system (i.e., lockings, pressure losses). A quick maintaining  reaction is possible and the overall safety level is increased. The measurement  system is based on PRODATs modularized internetworked construction kit and  framework PRODAT SENET. It architecture allows very flexible system configurations  and besides existing sensors and sensor systems customer specific requirements  can be easily solved. Besides using of the force or pressure sensors, digital  signals can be acquired if needed. Other possible quantities include  environmental workshop conditions such as humidity or temperature. Especially  the wireless system approach greatly simplifies the system usage, as typically a  large number of fast braking long cables is not required (in difference to a  number of different solutions on the market). By employing PRODAT SENET in the  PRODAT BKM-W system it supports either a standalone operation or an integration  into existing test & measurement systems and/or infrastructure. The  individual measurement system components, especially the sensors are battery  operated, and support runtimes of 12h and beyond (longer duration in dependence  of the user specific usage cycle are possible). The wireless communication  distance with line-of-sight is typically 100m. In typical operation conditions,  i.e., in the workshop with metal surroundings and when positioned at the bogies  the communication distances can decrease to typically 20 to 30m.
 Advantages  of a wireless variant in comparison to a cable-based approach are: 
  very  good calibration characteristicsProof  of acting forces between wheel and, i.e., brake shoe without moving railcar Proof  of important additional quantities, i.e., brake system pressuresDuring  measurement & testing other work on the railcar is still possible (not  exclusively blocked)long and expensive cables are not required (which usually leads to very long  measurement times as an installation and deinstallation is required)communication  distances up to 100m with line-of-sightcommunication distances in the workshop  typically between 20 to 30m (metallic surrounding)  Measurement system componentsPRODAT  BKM-C and BKM-W follow a modularized system architecture concept. Components  are assembled as required and are adapted if required by the customer.  Available components are: 
  brake  force measurement sensors in different construction variantsrepeater  unitssensor  for additional binary and analog signalsgateway  unitscharge  stationsmeasurement  PC or mobileadditional  measurement supporting utilitiesunique  solutions if required Promises of a condition  based monitoring of railcar brake systemsWear and  tear of the brake system are strongly dependent from the usage and the  operation conditions – of typical relevance are the time profiles of loads and  stresses as well as exceptional seldom events. The typical approach is to design  highly durable systems and carry out a maintenance in order to reach or extend  the expected system time of live. Hereby the standard is time based maintenance  approach. Is nevertheless a condition based approach employed and the full  brake system, as well as it critical subsystems are time-discreetly monitored  not only the overall safety level is increased  but also it is possible to decrease the overall system maintenance costs. As  other ,i.e., other competitors state, it is for example possible to extend maintenance  intervals if risk evaluation and strategies are employed (i.e., CSM 352/2009/EG).  Nevertheless  despite these strong economic advantages PRODATs goal and main driving force of  any customer using this system should be to increase the overall security level  of their owned and maintained rolling stock. Examples  |  |