"The knee bone's connected to the thigh bone..."

It seems that I was right about my reputation within the group as a train breaker sticking. Although I've had no further incidents, I'm still referred to as a Jonah.

In fact, this particular title could just as easily apply to one of our number who got a bit keen when exploring the differences between the Mark 1 version of the Class 317 and the slightly less old Mark 2. Despite warnings that the units we were exploring had been prepped for service and that we should leave them exactly as we'd found them, he noticed that the passcoms were different and decided to pull one. Cue several minutes of consternation as his group tried to work out how to reset it. Unfortunately, being the first I fear that this is not going to be enough to shift the attention away from myself.

Away from the diverting subject of breaking trains, we've been getting down to the minute details of our units. As a commuter I'd always dismissed them as being old, basic and a bit naff but, as a trainee driver, I'm learning a new respect for them from their hidden complexities. For example, I'd never known that the air suspension could sense the weight of each coach and automatically adjust the brake pressure in each brake step accordingly. That this is all done by air without any electronic intervention is quite amazing.

The flip side to this is that there are some daft design touches, particularly in relation to the positioning of air isolation cocks. Some units have an internal and external cock for some air systems, but these are in different places in the circuit for each system. Some parts of the air system don't have an isolating cock at all which would require the isolation of the entire coach from the rest of the train in the event of an air leak (e.g. the supplementary main air reservoir on Mark 2 units). A bigger headache is the positioning of a passenger bulkhead inside refurbished Mark 2 units which makes access to the isolation cocks all but totally impossible.

Still, it's nice to be outside in the fresh air after all those weeks stuck inside a classroom all the time. It certainly makes things a lot easier to understand when you can go out to a unit and see the systems and practice the procedures (or "play", as our instructor would have it).