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Home | The Machines | The Presenters | The Experts | Find out more
Introduction | Out of storage | Motor mechanics | Not quite good enough
This tram is an old friend of the Salvage Squad – they worked on it in the last series. In this new version of that programme, they have a chance to improve on what they've done. When they first see the tram, it's stuck at the back of a disused bus depot in St Helens. They have five months to get it running along Blackpool promenade once more.
Tramcar No 304 was delivered to Blackpool in June 1952 and was the first of a batch of single-deck trams that were the resort's first purchases after the end of the war. Incorporating Variable Automatic Multinotch Braking and Acceleration Control (VAMBAC) and rubber sandwiched wheel sets, they represented a considerable development of the British tram and were considered to be the most luxurious rail coaches ever built.
As the cars were still being delivered in 1953, the year that Queen Elizabeth II came to the throne, Blackpool decided to call them Coronation Cars.
The Squad's tram remained in service until 1970, when it was put into storage. Fifteen years later, tram enthusiast Philip Higgs bought the tram with the proceeds of a book about the history of the Blackpool tramway, which he had written when he was still a schoolboy. Philip started work on the restoration with volunteers from the Lancastrian Transport Trust. But progress was very slow.
The tram is one of the biggest challenges that the Salvage Squad have faced. Jerry takes on the task of restoring the complex and troublesome VAMBAC unit. Claire works on the trolley pole and tower, and the interior details, while Axel concentrates on the bodywork and the tram's electric motors.
The four motors need to be totally refurbished and Axel gets expert help from Dave Hesketh at Bowers Electricals. An electric motor is quite simple: the electricity enters at the back via small carbon blocks called the 'brush gear', which rub on contacts around the central axle. The electricity then energises dozens of powerful electromagnets in the central part of the motor, called the armature. These electromagnets then spin within a second set of magnets inside the main casing of the motor.
The first step is to withdraw the armature from the body of the motor and then remove the brush gear. Axel next has to wash the body and armature to remove dirt and carbon from the electrical coils. He then puts the cleaned armature in an oven to dry.
After that, Axel takes on a machining task. He puts the armature on the lathe to 'skim' the commutator – a cylindrical assembly of insulated conductors connected to the coils on the armature. He has to shave off a tiny amount of copper to ensure a good contact and then files out the gaps between each of the 200-odd contacts by hand. Finally, he assembles the brush gear with new springs and carbon brushes.
After fitting all the parts back together, Axel and Dave run the motor up to speed on the bench, using a tachometer to measure the rate of revolution of the armature shaft. It runs perfectly.
Unfortunately, despite all the hard work, when Philip takes the tram back out on to the promenade, the VAMBAC system won't work to its full capacity. It's back to the drawing board. Claire investigates, and discovers that the bearings in the gearbox are badly worn and the rotor shaft of the VAMBAC system is bent and can't supply full power to the motors. Claire and David have to remove the whole unit from the tram and replace the bearings and rotor arm.
When the work is complete, Philip takes the tram out again and it almost flies down the prom under the world famous Blackpool illuminations.
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