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'Right Click' here to download HPSS Technical Overview Document (2nd edition) (PDF) |
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Frequently Asked Questions
WHAT IS POWERLINK BACKDRIVE?The PowerLink Backdrive utilises the well proven concept of a torsional backdrive together with swing links. These and the high efficiency bearings and drive ratios, optimised for each size of switch, ensure maximum drive to the back of the switch rails to ensure precise, repeatable, reliable operation. Since its introduction there have been no reported incidents of problems driving switches closed at the back where forces are highest.The HPSA is the in bearer point machine providing the primary drive, locking and detection of the system. Multiple HPSA can be used to drive switches or a backdrive can be utilised. HPSS is the complete sub-system of ALD (actuation, lock and detection), the backdrive (where required) and supplementary detection contained in hollow bearers. This subsystem can be quickly integrated with a Switch and Crossing panel to meet all the requirements of RT/SRS/2001 including obstruction detection throughout. HOW DOES HPSS INTERFACE WITH THE S&C PANEL? Dependent upon rail standard, the Hollow Bearers of the HPSS have appropriate Slide Plates with the usual proprietary Stock Rail attachment (e.g. Schweihag, Vossloh, Pandrol). Toe Detectors are attached directly to the Stock Rail via a clamp arrangement (2 bolts) requiring no Stock Rail drillings. All Switch Rail interfaces are via drilled pairs of holes, through the web, for the location of supplied bolt-on brackets. The standard universal drillings at the toe are utilised. Each location of the Back-Drive and Supplementary Detection Stretcher Bars require a pair of holes in each Switch Rail for its attachment. No other attachments or drilling of the rail foot is necessary. There are therefore only 2 bolts per side at each hollow bearer location. All electrical connections are by the supplied approved pre-wired connectors. The torsion drive bar drops directly into its drive pins within each bearer and is held by the insertion of a single bolt at each clamp. CAN DIFFERENT SLIDE PLATES BE USED? The slide plates fitted are common to all bearers. Each bearer has 2 pairs of ‘half’ plates to allow rail connections to pass through the middle of the bearer. If an S&C manufacturer wishes to use their preferred slide plate arrangement, interface drawings with the bearers can be provided. PLEASE EXPLAIN THE OBSTRUCTION DETECTION CRITERIA It is a fundamental requirement written into the latest Network Rail specifications to have the capability to detect a 12mm (for 113lb) or 15mm (for UIC60) obstruction throughout the planed section of the switch. Clearly undetected obstructions could put the track out of gauge and cause an unsafe condition. It is the responsibility of the Switch and Crossing manufacturer to ensure their S&C system has this capability as the Points Machine on its own can only detect directly at the toe and indirectly at the back via the backdrive (if stiff enough). The stiffness of the switch rail, the position, the number and the size of drive forces will determine the location and setting of any supplementary detection required for each size/configuration of switch panel. IAD will work with the S&C system supplier on the number and position of supplementary detectors for HPSS for each switch size. Proof of compliance upon integration is very quick and simple with HPSS due to its continuously monitoring, contact-less position detection system. WHAT SORT OF CONDITION MONITORING IS REQUIRED FOR HPSS? As HPSS is designed for no scheduled maintenance, there is no requirement for Condition Monitoring of the ALD equipment. By virtue of the way the HPSA driven system works, certain parameters are measured and recorded as part of the normal operating cycle. This information can be very useful to assess the condition of the whole track panel. This data can be made available to external circuits (Condition Monitoring Systems) and used to establish track/panel condition. Parameters measured are:
These parameters are the only ones needed for HPSA to indicate the position of the whole switch. Further information can now be gathered at any site using a purpose designed handset. Remote interrogation of this logging handset is coming. WHAT IS IAD RAIL SYSTEMS ASSOCIATION WITH BALFOUR BEATTY? IAD Rail Systems are the designers and manufacturers of the HPSA, Supplementary Detection and PowerLink Backdrive; we have worked with Balfour Beatty Rail Engineering to develop the complete HPSS incorporating their original torsional Back-Drive sub-systems. IAD Rail Systems put together and submitted the complete Safety Case for the complete system, which led to its Product Acceptance for use in the Rail Infrastructure. IAD Rail Systems have subsequently taken responsibility for the torsional backdrive and incorporated their high efficiency PowerLink modifications. Balfour Beatty supply the components of hollow bearers and track support elements of the backdrive system. The complete HPSS is available through IAD Rail Systems to all manufacturers, stockists and infrastructure companies. WHAT IS THE SAFETY ACCEPTANCE STATUS OF HPSS? HPSS is to our knowledge the only system currently approved to RT/SRS/2001. An open Certificate of Acceptance PA05/579 has been issued by Network Rail for installation of HPSS into its infrastructure. The scope of application will be progressively widened on a case by case. Approval has already been provided for 54B, RT60 and swing nose crossing variants. For HPSS the complete system is approved including all stretcher bars, track interfaces, supplementary detection, hollow bearers etc. HPSS was designed from the outset with high speed in mind. The bearers are designed and qualified for the higher loadings. The machine drives the switch rail to the stock rail on each occasion thereby eliminating any facing point gap (save that caused by obstruction, which will be detected). The rugged construction, high reliability and availability
of the HPSS, coupled with the extra safety features inherent in its system
architecture make it ideal for high-speed use. |
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