How 92 stock trains work part 105.
Now on 92 stock every car, of which there are eight, has two sets of four wheels on a “truck”. Between the truck and the car is the suspension system, basically a big bag full of air. The car has a sensor that gauges how much weight is onboard and the suspension system inflates or deflates the bag as people get on and off.
Another clever little piece of kit adjusts the acceleration and braking depending on how much the train weighs while yet another do-da converts the weight information into an estimate of how many passengers are on the train, passes that onto Wood Lane and should there be a need to tip out and reverse they can pick a relatively uncrowded train. All in all the suspension system is pretty damn important.
Every now and then the bag just deflates on it’s own leaving that particular car with a very bumpy ride and if this happens we have to go back to the affected car, open up a cabinet under one of the perch seats and reset. Now that’s all very well if you happen to be at a station like EAA at 23:00 but if you are in the middle of a tunnel at 08:30 with 800 odd people jammed on and the failure is in the rear car it’s not so easy to get through. If that is the case we have to crawl along at around 30kph, the maximum safe speed for driving without suspension, until we reach the next station.
Fortunately I was a EAA at 23:00 though its still a long walk to the rear car.
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