The Turbostar and Electrostar platforms are a modular design, which share the same basic design, bodyshell and core structure, and are optimised for speedy manufacture and easy maintenance. They consist of a common underframe, which is created by seam-welding a number of aluminium alloy extrusions, upon which bodyside panels are mounted followed by a single piece roof, again made from extruded sections. The car ends (cabs) are made from glass-reinforced plastic and steel, and are huck-bolted onto the main car bodies. Underframe components are collected in ‘rafts’, which are bolted into slots on the underframe extrusion. The mostly aluminium alloy body gives light weight to help acceleration and energy efficiency.
The Class 172 differs mechanically to its older relations in several ways. The engine used is the more powerful and cleaner MTU 6H1800R83, the transmission is the mechanical 6-speed ZF Ecomat-Rail, and lighter Bombardier FLEXX-ECO bogies and hollow axles are used as well as half-height airdams. The exhaust system is also quieter and does not have the distinctive note of that of the Class 168/170/171.
Turbostars have been acquired for use by several train operating companies, each with different specifications. One of the more noticeable differences with later units compared to earlier ones are the larger headlights now specified for safety reasons.
Units are numbered 168 xxx, 170 xxx, 171 xxx, or 172 xxx, where xxx is the serial number of the unit. Individual carriages are numbered 50xxx and 79xxx for driving motor cars, and 54xxx, 55xxx and 56xxx for centre cars.
Working in multiple
One factor which contributes to the popularity of the Turbostars is that Class 170 units are fully capable of working in multiple with older types from the Class 15x Sprinter series of units as well as other units of the same class,[3] unlike all other types built since privatisation, giving them greater flexibility. However, there are issues with so-called "sandwich" formations, formed either as 170-15x-170 or 15x-170-15x, which causes problems with empty stock movements where up to four units of various types coupled together is common. A possible side effect of this is that Turbostars' performance is in line with the second generation 15x units, in fact being somewhat slower than a Class 150 or Class 156 on "short hop" workings, and slower than a Class 158 on longer distance workings unless there is enough 100 mph running to take advantage of the 10 mph higher top speed of the Class 170.
^"CLASS 170 'Turbostar'". Therailwaycentre.com. Archived from the original on 27 October 2007. Retrieved 22 May 2010.
^"CLASS 172 'Turbostar'". Therailwaycentre.com. Archived from the original on 17 January 2008. Retrieved 22 May 2010.
Further reading
Milner, Chris (May 2013). "The 'Turbostar' Story". The Railway Magazine. Vol. 159, no. 1345. Horncastle: Mortons Media Group. pp. 18–23. ISSN0033-8923. OCLC750645684.
West, Lee (7–20 October 1998). "'Turbostar' is ready to roll!". RAIL. No. 341. EMAP Apex Publications. pp. 22–25. ISSN0953-4563. OCLC49953699.