It’s often said in engineering circles that, if something looks right, then it is right. When Direct Rail Services (DRS) recently showcased the first of their new 15-strong fleet of Class 68 diesel- electric locomotives the sun shone and everything about 68002 ‘Intrepid’ looked very right indeed. Writes Stuart Marsh

That DRS are proud of the new locomotive was very obvious, and so they should be. Hailed as a ‘new generation’ locomotive, DRS says, ‘The new locomotive is set to deliver a significant performance benefit for both DRS and its clients.’ No kidding – this DRS venture is positively heroic!


The Class 68 simply exudes excellence, resplendent in an updated version of the DRS ‘compass’ livery. Its design is derived from the existing Vossloh ‘EuroLight’ four-axle locomotive which offers high power output and a low axle loading. DRS has worked closely in partnership with Beacon Rail Leasing Ltd in order to develop the concept of this new locomotive with Vossloh.

EuroLight uses components from the 20- 22 tonne axle load Vossloh Euro locomotive series, with weight reduction being achieved by switching to a lighter engine of the C175 series from Caterpillar Inc (CAT®) and a lighter alternator set and traction equipment from ABB Group.

In producing the Class 68, the EuroLight design had in turn to be adapted to fit the UK’s more restricted loading gauge. This UK version, which Vossloh calls UKLight, also offers a higher top speed – increased from 140km/h to 160 – and fuel capacity increased from 4,000 to 5,000 litres. It has an axle loading of 21.4 tonnes.

Manufacture of the locomotives is being undertaken by Vossloh España at its Valencia works – the same factory that built the Class 67 locomotives in 1999 when it was part of the GEC-Alstom group. The value of the Class 68 contract is around €45 million.


Positioned almost exactly at the centre point of the locomotive, the CAT C175-16 ACERTTM diesel engine is a derivative of Caterpillar’s very successful C175 series of 16-cylinder and 20-cylinder engines, used commonly in generator sets and heavy earth moving equipment. The C175 has been installed in locomotives elsewhere, notably the Progress Rail PR43C in the USA. This is, however, its first application in a British locomotive.

The C175-16 is a medium-speed four-stroke engine with a 175mm bore and 220mm stroke, giving a displacement of 84.7 litres and producing 3,755hp (2,800bkW) at 1,740rpm. It uses electronically controlled common rail fuel injection, which allows the injection events to be tuned precisely according to the demands placed on the engine. For instance, it is possible to provide multiple injection events, both before and after the main injection event on each power stroke. This injection strategy is varied depending upon many factors, including load, speed, engine temperature, air temperature and fuel temperature. The engine has four turbochargers with twin stage after-cooling.

The CAT engines meet European Stage IIIA emission standards, and can be modified to meet 2012 IIIB emission standards by replacing the exhaust silencer with a diesel particulate filter. However, because of the UK’s restricted loading gauge, this would involve considerable re-design work if it were to be applied to the Class 68.

Essential considerations for the Class 68 design were fuel consumption and ease of servicing/maintenance. It is claimed by DRS that the 4-stroke fuel-efficient CAT C175-16 should offer a significant fuel saving (on a per horsepower basis) over an EMD 2-stroke power unit, as used in the Class 66. A figure of 7.07% has been quoted, but in practice it will be very difficult, and some would say unfair, to directly compare two engines running at different powers, loads and speeds in locomotives that have different design concepts.


Engine servicing can be undertaken trackside, with intervals of 1,000 hours for minor services (oil change) and 18,000 hours for major servicing (top end overhaul). Finning UK Ltd is the only UK dealer for CAT equipment and will supply warranty support and parts, although DRS fitters are being trained by Vossloh. A purpose-built shed facility is being constructed by DRS at its Crewe Gresty Bridge depot to accommodate test and warranty engineers from Vossloh, ABB and Caterpillar. It will also house a dedicated stores facility for Class 68 spares and consumables.

In order to reduce fuel consumption even further, the diesel engine is fitted with automatic stop start technology. In service, the engine will shut down after a period of inactivity, for instance at a signal stop, although there is a manual override facility. This system has what DRS terms ‘day and night guard functionality’ – the engine will re-start if the coolant temperature falls below a pre-set threshold. This feature can be augmented by connecting the locomotive to a 415V 3-phase depot supply that will maintain coolant temperature, cab heating and demisters.


Caterpillar has worked closely with ABB in order to reduce the weight of the locomotive for UK use. The ABB alternator has been specifically designed for use with the C175 engine and is bolted directly to it.

Some components of the engine/alternator set have been cast in aluminium rather than steel in order to save weight. The Class 68 diesel engine itself weighs 11 tonnes as opposed to 12 tonnes for the standard C175 engine. A five-point flexible mounting system has been adopted for the engine/alternator unit. There are four mounting isolators at the front mounting point, and one rubber isolator on each of the four rear mounting points.

ABB’s traction system makes use of a WGX560 6-pole 3-phase brushless alternator that is directly coupled to the engine. The alternator supplies two traction packages (ABB Boardline CC1500 DE Compact Converters) each having a rectifier to create an intermediate DC supply. This DC system is required for electric train supply (ETS) and for dynamic braking. The drive electronics (AC800 PEC) incorporates adhesion control (anti slip), backed up by automatic sanding. There are two traction inverters and one auxiliary inverter per traction package, thus giving one traction inverter per traction motor. A traction fault condition will result in power being diverted to the other three traction motors.


In common with the Vossloh EuroLight locomotives, a Bo-Bo wheel arrangement has been adopted for the Class 68. The bogies are the same as those used on the RENFE Class 334 (Vossloh Euro 3000) high speed diesel electric locomotives in Spain. Primary and secondary suspension is by means of coil springs.

The ABB 4FRA6063 AC traction motors use squirrel-cage (brushless) technology and each has a rating of 600 kW at 4400 rpm. In order to reduce the unsprung mass, the traction motors are frame mounted and have flexible quill drives. DRS claims that, because of the state of the art adhesion control and braking systems, the 2-axle bogie arrangement will out-perform the three- axle bogies of the Class 66. Braking on the Class 68 is achieved by a seamless blend of rheostatic and disc air brakes.


Locomotive 68002 was shipped to Southampton docks during January 2014 and was then transported by road to Carlisle Kingmoor depot. Dynamic trials between Carlisle and Crewe began in February as part of an ongoing acceptance process.

At the time of writing, the locomotive had yet to move under its own power on a UK main line. However, since December 2013, number 68001 has been undergoing extensive dynamic testing at the Velim testing circuit in the Czech Republic. At the same time, telemetry from two EuroLight locomotives in service in Germany and Italy was being examined closely. The Class 68 locomotives are fitted with two sets of telemetry equipment, one being exclusively for the CAT diesel engine. This equipment will be fitted to all fifteen members of the DRS fleet for prescriptive performance analysis, as well as hard fault reporting.

Locomotives 68003 and 68004 were expected to be completed in Valencia by mid-March. They were then scheduled for shipment to Liverpool docks and haulage by rail to Crewe. DRS would not be drawn on the anticipated timescale for UK acceptance of the Class 68. Completion date for the build contract remains uncertain too, but all fifteen locomotives are expected to be in the UK by late summer 2014.

Into service

The potential offered by Class 68 to DRS is enormous. It needs to be of course, considering the capital outlay. These locomotives are a true mixed traffic design, combining a 100mph capability with an approximate 300kN tractive effort.

The fleet will need to work seven days per week, so it is anticipated that they will be used on a wide variety of applications. They are ideally suited to high speed container traffic and passenger charter trains, but their high top speed will also make them useful for standby rescue duties.

Two Class 68s can be worked in multiple, but they are unable to work in multiple with other locomotive types. They have been given RA7 route availability.


The 100mph performance offers the potential for new high-speed freight services. DRS also remains hopeful of expanding its passenger operation, which is currently focused on the charter train market. Neil McNicholas, managing director of Direct Rail Services, has said: “This is another important milestone in the strategic development of Direct Rail Services. The Class 68 locomotives are set to further extend DRS’ capabilities and give our clients an even faster and more efficient service. The Class 68 is just the first component of a wider DRS fleet strategy designed to ensure that we can offer our clients the most efficient and flexible service well into the future.”

Electric version

That strategy includes an electric version of the Class 68, to be designated Class 88. Again in partnership with Beacon Rail, DRS placed an order with Vossloh last September for ten Class 88 locomotives. These will be a direct development of the Class 68, but with 25kV electric and diesel-electric modes. They will have a 4MW rating using ABB AC traction equipment plus a 950hp Caterpillar C27 diesel engine for use where there is no overhead line equipment. This provides more than so-called ‘last mile’ (i.e. shunting) capability. The Class 88 is a true ‘dual mode’ locomotive that has been designed to haul a train using diesel power alone. Indeed, the starting tractive effort is similar in electrical and diesel propulsion modes.

The Class 88 will share many of the features of the Class 68, including the bodyshell, braking system, bogies, traction equipment and control software. Again, these locomotives will be of the mixed traffic type. Delivery of the first Class 88 is expected in late 2015, with completion of the contract by spring 2016.


DRS has an option to order further Class 68 locomotives, but no decision on this has yet been made public. Under EU emissions rulings, just 26 further new-build Stage IIIA rated locomotives are allowed before the 31 December 2014 deadline – 16 for anywhere in Europe, plus 10 more for the UK. There is however no restriction on replacement Stage IIIA power units for existing locomotives. The space required for the additional equipment needed to convert the C175-16 engine to Stage IIIB compliance means that the class 68 would require substantial redesign work. A decision from DRS on whether to purchase further Class 68s will therefore be required soon.

With the benefits that the Class 68 and Class 88 locomotives will bring, the success story of Direct Rail Services is set to enter a bold new phase. It’s a story that began humbly in 1995 with just five second hand Class 20 locomotives.

Today DRS is a profitable and dynamic business that is achieving sustained growth. By acquiring new, state of the art locomotive fleets, DRS clearly seeks to consolidate itself at the forefront of rail operations within the UK. It’s not just about technical capability – successful companies also understand the value of image and style … and Class 68 has bags of it!