Service weight
The designation service weight (in Germany service weight ) is used for locomotives . It is the term used for the total weight of a locomotive in active service . The service weight differs from the curb weight in that the consumables are also included here. It is a theoretical value as the total weight of a working locomotive decreases as it moves. Nevertheless, a value for the total weight of the locomotive is necessary for various calculations (e.g. brake calculation). This theoretical value is used for this.
As a stand-alone designation, service weight is mainly used for diesel and electric locomotives . An isolated service weight is rather unusual for steam locomotives . Since the service weight changes too much here, work is also carried out with - mostly percentage - weight specifications of the supplies (service weight with full supplies, service weight with half supplies, etc.).
The service weight is made up of the unladen weight of the locomotive, the average consumable material (as a rule, two thirds of the full stock is used) and, if applicable, ballast . In the case of railcars, there is also the load weight.
The service weight is often an important factor when tendering vehicles, because it is related to the possible axle load or the friction weight . The friction weight is an important value, especially in adhesion vehicles , as the maximum possible starting tractive effort today is usually limited by the static friction and no longer by the locomotive performance. With some vehicle series it is possible to achieve a different service weight by adding ballast. As a rule, an attempt is made to bring the service weight to the maximum permissible value. This means that with a permissible axle pressure of 21 tons, the desired service weight for a four-axle locomotive will be just under 84 tons.
The word "weight" contained in the technical term service weight is physically imprecise. In the physical sense, the service weight means the mass and not the weight , it is also given in units of mass ( kilograms , tons ).