HOW DO THEY DO THAT? - 3
IN THE THIRD OF OUR SERIES WE LOOK AT
TAMPING THE LINE
With a Moon Buggy? Well not quite but the main operating compartment or 'the downstairs cab', as Steve, Charles and Paul - the three machine operators call it; is reminiscent of a space age vehicle with its multitude of switches, computer game like controllers, foot pedals, flashing lights and read out instruments. It may look like an oversize Tonka Toy but the Plasser Theurer 275 P & C Tamper is a very specialised piece of kit.
 P & C stands for points and crossings - as opposed to a plain line tamper which simply deals with runs of plain track between turnouts which have sleepers of regular lengths placed at regular intervals between each other. Think of a point which has differing sleeper lengths, point blades, check rails and electric motors to navigate round and you get the idea of why a vastly different machine is needed. My guide to the technical bits was Steve Goodwood and hopefully, with the aid of the photographs you'll begin to see how it all works.
But first of all we need to know why a length of track has to be tamped in the first place. In the case of a relay, such as the one just carried out at Bulkamore, where track is laid on an area stripped of its old ballast and re-levelling of the base surface takes place, there will inevitably be fairly instant settling of the ground as the track panels are laid on it. Even when new ballast is laid the new formation can take on the appearance of a switchback ride. In the case of Bulkamore it's even more complicated as the whole section is on a sweeping curve and track cant has to be taken into account. It would take a large gang of men many days to lift sleepers and pack the ballast to the correct geometry manually. A machine like the Plasser Theurer can do the job in hours, making sure the transition of the curve is even and sorting out the geometry as it goes along lifting and packing.
Track that is not being relaid may also need attention as the ballast beneath it can settle unevenly over the years, especially over points and crossings where the geometry can also come out of true. In the same way that damage could be done to a car's suspension units by driving over potholes for long periods it's just as easy to damage or break springs on a locomotive if the track is not in good condition. And it's all of this permanent way upkeep that has to be done in the railway's 'closed winter season', with the P.W. gang fighting both the elements and the clock. Which is often why the call to hire in a specialist machine goes out.
One of the operators goes along the track to be tamped with a track gauge and checks the levels of the rail, and with the measuring device determines how much each side, or one side only, of the track needs to be raised and packed. He sprays the measurement in a bright green paint in mm's onto the sleepers so that as the machine moves along the operators know who much to raise the track by and set the controls accordingly. This is why it is essential that they have the view onto the track through their operating windows. Sometimes, especially with a relay, panels of track may need to be moved sideways in order to get perfect alignment and the machine is capable of that too. Obstructions such as point rodding or S & T cables are also sprayed with the fluorescent green paint so that the grab arm and tines can be adjusted around them. An exacting science made easier by the use of this large machine which also saves countless man hours of difficult and heavy manual labour. |
