It is amazing how many people think that preserving a diesel train is a matter of getting in it and turning a key! This sequence of pictures by Michael Young show the work involved in changing a final drive gearbox on power car 51618 which took place in December 2007. The first job is to remove the bogie, onto which the gearbox is fixed - this involves using a 50 ton crane to lift the rear of the unit so that the bogie can be disconnected and rolled out.

This is the replacement final drive gearbox. As can be seen from the picture the axle goes straight through the middle of the unit so it has to be split in half to allow it to be fitted to the bogie. We were very lucky to be able to locate a reconditioned unit through the Midland Railway DMU Group. Note the size of the gearbox!

These are the gears at the top of the failed final drive gearbox. The assembly on the left allows the train to run at an equal speed in either direction. Unfortunately though they are working correctly the large gear on the right is no longer transmitting the drive to the axle below. It is thought that a key has sheared inside the box and that the repair will involve stripping down this component.

The old final drive gearbox has been removed from round the axle using a second crane to remove the heavy components. this leaves in place the bearings and the actual drive to the axle. We were fortunate that we were able to field ten volunteers to carry out this task and we were some five hours into the operation at this point.

The new gearbox has been split into two. The top half was craned into position and the bottom half jacked up to meet it. The two halves were then bolted together, making sure that the bearings and the shims underneath them were in the right place. The gearbox has a torque reaction arm at the far side which prevents it rotating round the axle and this had to be refitted once the gearbox was back in place. The old gearbox was also bolted back together so that it could be placed in one of the mobile workshops(pictured at the rear) to be repaired.

Finally the completed bogie is rolled back into position under the coach so that the crane can lower the body back down onto the wheels. Even then the job is not over as the air system, vacuum system and propellor shafts have all to be reconnected. This mating of the two halves was accomplished just before darkness fell and so the job was completed the following day when the light returned.