Looking back
of putting train with a high power to weight ratio on a purpose built track, was not seen as viable in the UK, since no route carried enough traffic to warrant the costs. The option of running trains faster with minimal track modification raised the possibility of increasing speed and capacity on all routes. The current discussion of HS2 uses similar arguments to reach the opposite conclusion.
A short experimental train, APT-E, was designed utilising gas-turbine engines then being developed by British Leyland (BL) for trucks and buses. Ten were used as generator sets, eight for traction and two for other power services in the two end power cars. Standard traction motors powered the end bogies with fully articulated trailer suspensions under each pair of vehicle ends. The train was articulated to reduce weight by reducing the number of bogies. In addition, a two-car dummy train with the same frame structure as the power cars and similar but unpowered suspensions was used for towing trials. Initial tests of the powered train were delayed and disrupted by union action, but the 2-car towed tests on the Old Dalby test track south of Nottingham quickly revealed some problems.
Rate sensitive dampers, new to the railways, had to be used to give a stiff reaction to the dynamic vibrations, but allow larger slow movement when entering curves or passing over points and crossings. The suspension connections relied on the stiffness of the body structures to react the vibration loadings. However, there were vibration modes within the bodies and, because of the fully articulated configuration, even whole train vibrations, which were excited by the suspension frequencies. The powered train was modified to test these findings when it did run (breaking the UK rail speed record). A new set of parameters were evolved for the next stage, pre-production prototypes to be used in service. By this time, BL had withdrawn from gas-turbine work and the APT-Ps were designed as electric trains for the West Coast mainline from London to Glasgow.
To avoid the interactions between the suspension frequencies and the train vibrations, the prototypes were semi- articulated, with more flexibility between cars. In addition, all vehicles were required to have much stiffer body structures. It was
16 First P-train power car
APT-P at Derby Works
APT-P tilting at speed
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36