Development of a light-weight tripcock

The requirement for mechanical tripcocks is now limited to a few locations around the world, each with its own particular requirements and the device is seen by many as old technology. Several recent incidents resulting from signals passed at danger have brought this long-established safety technology back into focus as a simple and visibly reliable way of stopping a train that is entering a danger zone. A market for a new generation of tripcocks was identified in 1997 when a requirement for 140 km/h tripcocks in the UK market provided the impetus to review the worldwide requirements for these devices. It also allowed us to explore the potential for a range of new Tripcocks using a modular approach to maximise the commercial opportunities for the investment. The review showed that the tripcocks in use could be resolved into three styles that would need to be covered by the new modular approach. These are categorised as Australian, UK & US types and will be referred to by these names through the following paper. The Australian style is for unidirectional operation, self-resetting (i.e. when the "brake pipe" pressure falls to a low value), with an out-of-service manual latch in the tripped direction and an optional remote latch in the non-tripped direction. The UK style is also for unidirectional operation, mechanically latched in the tripped position and pneumatically or mechanically reset. The US style is bi-directional, self-resetting (when the "brake pipe" pressure falls to a low value) with an out-of-service manual latch in a tripped position. One of the other factors to emerge from the review was the need to ensure that the tripcock will survive being immersed in water since there have been many occasions when certainly the Australian & US devices are known to have been subject to immersion in flood waters. Tripcocks of the current generation are all heavy devices, which rely on their mass and mechanical strength of construction to survive the impact with the train stop and to withstand the shock, vibration and fatigue imposed from being axlebox mounted. Heavy axlebox-mounted devices are not compatible with modern lightweight rolling stock that relies on achieving ride and road holding through low un-sprung mass. There were already concerns expressed by some operating authorities about the weight of the existing tripcocks and a stated desire that any new breed should be significantly lighter, to meet the need for lightweight running gear, to aid installation & removal and address Health & Safety issues. This confirmed the importance of abandoning the existing heavy construction and adopting a completely novel approach to the new tripcock design. The outcome of the worldwide review was positive and work began on the new tripcock design in 1997.

Media Info

  • Pagination: 16p.
  • Monograph Title: AusRAIL PLUS 2003, investing in Australian rail - strategies and solutions, 17-19 November 2003, Sydney, NSW, Australia

Subject/Index Terms

Filing Info

  • Accession Number: 01516973
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ATRI
  • Created Date: Mar 4 2014 8:01PM