Modular point machine
CURRENTLY undergoing endurance testing at Chippenham is a prototype Surelock MW21 point machine developed by Westinghouse Rail Systems. Intended for the Metronet contract to resignal much of the London Underground, the MW21 is also compatible with RT60 requirements on the UK national rail network.
The low-profile machine is designed for mounting in the centre of the track, with drives on each side to the two blades. A side-mounted version is under development. Weighing just 151 kg, the unit has separate motor, drive, escapement, control and locking assemblies, which can be swapped in under 6min to minimise the access time for maintenance. All modules are secured with a single size of bolt, and designed for a maintenance interval of 12 months and 1 million operations between overhauls.
The 110V motor provides 8 kN, throwing the point in less than 3sec. Electronically detected shear pins in the drive provide run-through protection, and provision is also made for a linear back-drive. To suit metro applications, the unit is designed to be flood resistant, and has been successfully tested in water up to 600mm deep.
Westinghouse Rail Systems, UK
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