Class 73 rebuilds for the twenty first century
Since privatisation the class 73 locomotives have had two main uses leading to their continued service life. Initially they were in fleet service with Gatwick Express until replaced by the Class 460 units with much of the rest of the fleet gravitating to engineering trains for Network Rail provided by various suppliers, but principally to GB Railfreight (GBRf) who now own 14 examples of the class. They have found this niche because they are a go-anywhere locomotive with good route availability and with the combination of diesel or electric power are capable of most jobs; given their age they are also largely life-expired with only running costs to meet.
To enable the existing fleet to continue operationally has led GBRf to undertake a major investment with a very significant rebuild of the locos enabling greater flexibility for the future and a further life of at least 25 years (and probably more). Also the locomotives were showing signs of age. Testing of a locomotive showed that the output was now around 425hp from the English Electric 4RKT units, merely reflecting their age, yet running on the third rail output was around 2400hp. Another problem related to age is the poor spare part availability which is limiting operational time.
The reconstruction work is being undertaken in the Wabtec Rail owned works of Brush Traction Loughborough and initially three locomotives are being rebuilt: 73209, 73204 and 73206. 73209 (formerly Alison) was in withdrawn state having last been used at Celsa’s facility in Cardiff for shunting but then suffered fire damage and had been at Loughborough since mid-2011. 73204 was due for an overhaul and 73206 (Lisa) was chosen because the wheels were life expired. Although built in ???? the locomotives have seen little major works attention since around 1992, although the 73/2 fleet was well looked after at Stewarts Lane whilst working the Gatwick services and since then the GBRf 73s have been maintained at St Leonards.
The locomotives are being stripped down and the parts to be re-used are the bogies, buffers, mainframe, drawgear and the traction motors, although all components being re-used will be fully overhauled. Like many steam locomotive rebuilds it is hard to say that they new – but there will be a lot of new kit on these locos. Stripping down the bodywork to basics has identified some corrosion and this will lead to repair and replacement as appropriate.
Once stripped down to parts the rebuild commences and central is a new power unit to replace the venerable EE Diesel with originally a 600 hp rating. In its place will be a new MTU engine (8V4000R43L) capable of 1500hp (or 1600hp depending on the source) plus a new AC alternator. Remarkably the new engine will bring a three tonne weight reduction as well as more power. The new engine will need more cooling so there will be air vents on the roof and on the side of the class 73. The engines have already been started in Germany before being shipped over to the UK.
The old style engine was started from traction batteries but these will also vanish and in a first for UK traction a CaPoS starter engine will be fitted which consists of a Capacitor Power Store along with a pre-heater as the engine needs to be at 25 deg C to start. The CaPoS starter is an MTU design for the series 4000 engines and consists of a series of capacitors which gather and store electricity when the locomotive is on the move. Electric storage in capacitors rather than batteries has been commonplace for a long time. This change alone should bring much improved operational reliability.
Between the cabs there is a lot of kit to be fitted in, so working back from no 1 end. At floor level a traction motor blower plus the additional ballast, then a rectifier and an alternator, various MTU related electronics before reaching the new diesel power unit. Behind the No 2 can are two cabinets one containing the chopper control and the other the auxiliary cubicle. Mounted under the solebar are fuel tanks (re-used but due to lower consumption will actually permit an increased range) and the CaPoS unit, AWS receiver plus a compressor etc. At roof level there is a silencer, TPWS and OTMR equipment, hydrostatic fan and cooler group (the header tank will be larger than the previous version to give greater cooling as the previous smaller size was one of the reasons for overheating) and a roof mounted headlight. The roof mounted horns are retained.
Whilst the traction motors are being refurbished all other electric motors which are currently DC will be removed and replaced by AC ones – including the windscreen wipers. The windscreens will be replaced – costing more than £10k each – but the centre window for the headcode display will not be replaced but will instead house some inverters, the GSM-R equipment and possibly for ERTMS in the future.
The braking systems are to be simplified with vacuum and the electro-pneumatic options removed leaving simple and twin-pipe air. This will also bring maintenance savings. New monobloc wheels will be fitted to the refurbished bogies. No tripcocks are being fitted so cannot work on LU, but this could be added although for fourth rail working the bogies would also need modification.
The cabs are receiving a lot of attention as well. Dual driving position and controller position are being maintained but there is a new cab control desk and layout and together with the significant hardware changes the drivers will need a two or three day conversion course to learn about the differences. Cab doors now have fixed windows which will remove drafts and make driving more congenial.
I have mentioned above the weight reduction but overall the final build will be the same weight as before as a ballast block will be added to ensure weight and braking capacity are unaltered.
Externally there will be new LED light clusters and a central headlight. The standard jumper cables will be retained but in addition there will be in addition a socket similar to the design on class 66 and so overall there will be possibilities of multiple working with other Class 73 (except 73/0), NR Driving Van Trailers, class 66 and GLVs of class 489. They will appear in the current GBRf livery when complete.
They will become type 3 when operating under diesel power and will therefore be able to get loads moving more quickly than at present. Maximum speed of 90mph can be achieved both under electric and diesel operation. ETH is retained with an index of 38 and again applies both under diesel and electric power. The locomotives can switch from electric to diesel and vice versa whilst on the move.
Initially numbering was to be in the range 73901 upwards but this has now been amended to 73961 upwards. 73961 (formerly 73209) is close to completion at the time of writing and will undergo four weeks of static testing before moving to the Great Central Railway during March for dynamic testing, although the later completions should go direct to traffic. 73204 will become 73962 and 73206 will become 73963. Once 73962 has been completed a fourth locomotive will be commence in the works and may come from either 73208, 73205 or 73207 as they all have many operational hours since works visits. A fifth locomotive will follow and if the initial results are seen as beneficial then GBRf will proceed with at least a further five rebuilds and may eventually complete their fleet plus any class 73 added to the fleet. Current planning is that 73119 and 73136 will be the last to be rebuilt as both have dual brakes at present.
And with a greater range and more power available greater use away from the former Southern Region seems likely for the rebuilt locomotives. The first five rebuilds are already contracted by GBRf to Network Rail on a ten year deal which will see them used widely potentially with the Network Measurement Train which is currently hauled by class 31 and 37 locomotives.
However this is not the only class 73 rebuild being undertaken as Railway Vehicle Engineering Ltd based in Derby announced back in 2011 a plan to undertake a major rebuild of two class 73 again replacing the EE diesel engine with two Cummins QSK19 each capable of producing 750 hp with the potential of using one or both power packs as well as retaining DC operation. These are the same engines as in Voyager/Meridian units.
Design work on this has taken a while but in June 2013 Patrick McLoughlin, Secretary of State for Transport formally lowered the first power pack into 73104 and the indications are that the locomotive should be available for traffic in the near future. 73211 should also be rebuilt in the same way. This is a huge and somewhat speculative investment as it is not clear that a particular user for these rebuilds has been identified, although Network Rail expressed interest in the original plans it is not clear if this has been overtaken by the GBRf rebuilds discussed above.
The bogies will undergo major rebuilding with new braking gear but re-use of the wheelsets and a technical challenge in making it all work with the third rail once re-assembled. These two locos are expected to be renumbered 73951 and 73952.
In additional to the Cummins engines the DC control systems were to be removed and replaced by a DC chopper control whilst in a similar fashion to the GBRf rebuilds significant re-work was to be undertaken on the locomotives to provide them with a new long life as good as new.
It was originally anticipated that these two locomotives would be operational by now – however the technical challenges and testing seem to have caused delays.