Perhaps the most exciting part of my engineering training was studying locomotives at Crewe Works. I was really looking forward to getting up close and personal with actual locomotives!
Crewe Works Erecting Shop
So far, I had only experienced workshops dealing with the manufacture and repair of locomotive parts. At the time, the well-respected Reg Partridge was the Erecting Shop superintendent. I was welcomed by him introduced to his department. As well as the Erecting Shop (or Ten shop as it was called) his department included the Power Unit Repair Shop. This was nicknamed ‘The Blue Room’ by the guys on the shop floor. Reg was also responsible for the diesel test facility which was located opposite the Erecting Shop. Initially, I spent time in the Blue Room where locomotive power units were overhauled. The primary parts of a power unit from diesel-electric locomotives comprises the diesel engine and the electric generator set. The generators were removed and sent to the Traction Shop. The engines were dismantled. Fuel pumps went to the Pump Room and cylinder heads to the Arcade which was a workshop between the Blue Room and the Machine Shop. The Arcade was also where we overhauled steam generators from diesel locomotives.
I remember seeing Spanner, Clayton and Stone type generators. Cylinder heads were cleaned before being crack detected. This process involved spraying known vulnerable areas with a specialist white paint and placing a magnet across the area before squirting on penetrating dye containing iron filings. If there was a crack, the iron filings would line up along the crack due to each side of the crack becoming different magnetic poles. This process is still used and can sometimes be seen on bogie frames. I saw Class 40’s in the works with their huge bogie side plates plastered with white paint and dye penetrant. The length of these frames is their Achilles heal. They didn’t like going round tight curves including certain points and crossovers and the stresses resulted in cracks in the bogie frame.
The Works used a process called ‘Metaloking’ to repair cracks in the diesel engine cylinder heads. This involved drilling a series of holes perpendicular to the crack using a special jig to ensure the holes were in line and spread evenly. Special keys are then inserted and corked into place to hold the crack together. Further holes are drilled along the length of the crack and special threaded bolts screwed in. The keys and bolts are then dressed off and ground smooth. This method avoids the need for welding which with cast iron can be tricky.
Checking the Webbing
Di-penetrant method was also used for checking in the webbing of the engine crank cases while in the Blue Room. These are the parts that support the crankshaft and so are subject to major stresses due in part to the rotational forces experienced. Some of you reading this will remember that sometime after the Class 47’s were introduced excessive cracking in the crank cases resulted in the horsepower rating being reduced from 2,750 BHP to around 2,580 BHP. There were mass engine changes during the mid to late 1960’s. Engines were transported to Vickers of Barrow for attention.
After reassembling the engine, including the fitment of the generator set, the power unit underwent static testing in a sound proof booth at the end of the Blue Room. From memory, this was to ensure the engine itself was operating correctly rather than load test the generator as this would be done with the power unit installed in the locomotive on the diesel test area.
The New Shop at Crewe Works
Class 86 outside the Traction Shop at Crewe Works
My next workshop was called the New Shop. This was sandwiched between the Traction Shop and the New Paint Shop. The Traction Shop was where electrical machines including traction motors and generators were overhauled.
The New Shop was engaged in the overhaul of electric locomotive. Both 25,000v AC and the 1500v DC Class 76 Woodhead Route locomotives.
The Woodhead Route Electrics were probably the most well-built locomotives I’ve ever seen. When they came into the works although they were stripped of component parts for repair, it was usually just a case of cleaning them as the amount of wear was minimal.
‘Secret’ Locomotive Test Track
One little known aspect of Crewe Works association with the DC Woodhead Electrics was that there was a test track where both static and dynamic tests could take place. It was located adjacent to the Chester line but on the other side to the Works opposite the Melts Workshop. There was a short isolated section of overhead electrified line at 1500v DC. A Class 76 would be towed over from the Works across the Eagle Bridge that used to span the Chester line, and shunted onto this isolated electrified siding. The remainder of the sidings on the site were powered at 25,000v AC for the electric traction depot that maintain the West Coast Main Line electric locomotives.
Raising the Pantograph
The first job was to get at least one of the two pantographs raised. There are at least three ways to do this. The first is to run the compressor which is powered off the batteries. This charged the air system and once sufficient pressure was achieved the ‘Pantograph Up’ button could be pressed. Air is supplied to an operating cylinder acting on a set of springs which raise the pantograph bringing it into contact with the overhead catenary rewire.
If the batteries were a bit flat the pantograph could be raised by a two-way acting hand pump located in the corridor between two cabs. A three-way valve connected the pantograph air supply to either an air reservoir which was charged by the compressor or this hand pump.
The thing was this pump was quite hard to operate so there was a third way to get the pantograph up and keep it there. Along the corridor between the two cabs could be found a wooden pole. This could be fed out through one of the side windows. One end would then be placed on the pantograph head before pushing it up to make contact with the overhead live equipment (OLE). Not something you would do with a 25,000v electric locomotive. Power would then be supplied from the OLE to the compressor and once sufficient air was obtained again the ‘Pantograph Up’ button could be pressed and the pan would remain in the raised position.
Class 76 Woodhead Electric Brake Systems
The Class 76 Woodhead Electric is a very sophisticated locomotive insofar as it has five braking systems. First of all there is the regenerative brake. In this the traction motors became generators when braking was required and the electrical energy fed back to the OLE. This was generally used when the locomotive was running down a gradient. The generated power would then be used by locomotives working up the gradient. Secondly there are Rheostatic brakes. Again this system used the traction motors as generators but in this case the electrical energy was fed into a bank of resistors. This was used for speeds below 20mph as the regenerative braking system could not be used as it would not stop the locomotive – it only slowed it down. A third system was the air brake system which applies air brakes to the locomotive brake blocks and when hauling an air braked train proportionally to those of each vehicle.
The fourth type of braking system is vacuum brakes which was used to provide proportional control for operating trains fitted with vacuum brakes. Finally there is the hand brake.
The drivers desk of Class 76 number 76038 from which I drove this locomotive at Crewe.
I did have the opportunity to drive to Class 76 that was being tested. It was 76038 which originally had been number 26050 and named Stentor. I felt very privileged to have driven this locomotive especially at such a rare location for this type.
Locomotive Tap Changes
I spent further time in the New Shop where I worked with a fitter responsible for overhauling the tap changers from Class 86 and 87 electric locomotives. Basically the tap changer is used to control the power required from the transformer to power the locomotive. There are 38 taps which correspond with the number of notches available to the driver via his power control handle. A notch indicator is provided on the drivers desk panel. The tap changer comprises of two sets of fingers which make contact with each of the taps in turn and are moved along by a chain powered by an electric motor. It was a skilled job ensuring that the tap changer is set up correctly and I was shown how to do this by the expert. I can’t recall his name but hopefully someone reading this will remember.
I moved next to the Erecting Shop where the High Speed Train power car building was in full production. There were two lines of new build bodies. The fiberglass cabs were manufactured at Derby Litchurch Lane and were transported to Crewe on small flat wagons called Conflats. Usually two or three of these cabs were stored awaiting fitment to the body on stands in the workshop.
New build work was so much cleaner than that on the overhaul of locomotives that had spent years in traffic. Locomotives for overhaul would be brought into the Erecting Shop at the western end. They would be lifted off their bogies and placed on stands. The underneath would then be steam cleaned in a sectioned off area before being craned over to stands further up the workshop. As the overhaul progressed, the locomotive would be reunited with a set of refurbished bogies.
What was called sequence testing would then be conducted. This was to check all the control systems on the locomotive. For example, that the reverser operated correctly and that relays would energize or de-energize when controls were operated.
This testing would be undertaken by a Finished Work Inspector. I worked alongside a very knowledgeable and super guy called Joe Beadle. This experience taught me a great deal about how a diesel locomotive works. It put me in a great position to understand how locomotives were tested on the diesel test facility. I will cover my time there in the future blog.
I’ve recently learnt that Erecting Shop is to be demolished along with the Blue Room, Arcade and Machine Shops. I find this very sad given the history of these buildings. I’m so glad that I have my memories and I have no wish to visit the site today. With all the deserved accolades being directed at the success of the HST’s of late it is a great shame that the place of their construction is being destroyed.