>>1609415>i definitely want to learn all of the different classes of trains.You should understand the basics of the TOPS numbering system in order to easily identify locomotives and multiple units (MU) completely accurately.
The basic format of TOPS goes as follows: (C)CC SNN, where:
C = the class of locomotive/MU. These may either be 3 digits or two digits.
S = the subclass of locomotive/MU. This number identifies a particular variant of a class.
N = the number of that specific locomotive/MU, it is usually assigned in order of production.
The most general way to describe a family of locomotive/MUs is by referring to the class only (e.g. Class 68), but if you want to single out a specific variant then you should refer to it by the subclass as well (e.g. Class 320/3).
As a general rule, all locomotives have double digit classes, whereas multiple units come in triple digit classes. From my memory:
Classes 1-20 are diesel shunters, responsible for shuffling rolling stock around in yards.
Classes 20-80 are diesel locomotives, which are seldom used nowadays beyond heritage trips and some freight journeys.
Classes 80-99 are electric locomotives, with the introduction of the Class 800 IETs, these too are increasingly rare in Britain.
Classes 100-130 are first generation diesel multiple units (DMU), generally built in the 50s to replace rural steam services.
Classes 140-149 are Pacers, which are DMUs built in the 80s from bus parts as a temporary measure to replace the first generation DMUs, but have since been the primary DMUs in rural (and sometimes urban) northern services, they have only been replaced very recently.
Bear in mind that these are just ranges of numbers that will contain the types of trains that I've described, not every number in the ranges specified will be assigned. I will continue this in my next post.
