MODULAR TRAIN: ENERGY SAVING

Abstract

The article refers to comparative analysis of traditional and modular schemes of freight rail train. The author substantiates relative advantages and describes outlook for modular trains. The limits of using of super powerful locomotives are shown, followed by preliminary assessment of low level of their power and economic efficiency.

Existing theory of locomotive traction [1] considers motion of a train which is a system of material objects (locomotive and cars) as a motion of a material point where all the weight of the train is concentrated. This much reduced mathematical model permitted to analyze progressive motion of the train by the laws of Newton. Automatically ignored are energy processes within the system of material bodies itself. Particularly friction losses in the coupling and in other devices, which participate in transmission of power from locomotive to wheel pairs, are not considered, thus coming into conflict with tribology laws.

The author suggests another approach of traction calculation, when the train is simulated as consecutive and parallel kinematic chain (KC). Simultaneously the most efficient variant of KC is determined. As alternative to traditional scheme of rail train leaded by locomotive (pic.1a) the author proposes to consider a construction where kinematic links are simplified and partially replaced by electric links (pic.1b). This scheme is named modular scheme. A module represents a cluster unit of rolling stock with motor car coupled with one or several ordinary (without traction) cars.

The author admits that the realization of motor car scheme is technically complicated see large number of power consumers in the train. Nevertheless the motor car scheme has been largely developed for electric passenger trains. That’s why author argues that similar scheme should not be positively rejected for freight trains in future. If we assume that the further development of heavy load trains continues by placing more and more powerful locomotives at the head of trains, it will cause reduced power efficiency, growing risk of their stretching, exceeding of admissible value of friction of wheel pairs of locomotive, breaking of couplers, deformation of lower frame of first cars, which are designed with account for definite value of stretching and impact load.

On the contrary the development of heavy load trains on the basis of modular technology could help to maintain (or even to reduce) traction load on the coupler within admissible values and to compose trains of any freight load, without contradicting physics laws, defining rate of adhesion of wheel pair with rail, and without increasing axle load, section power and weight of locomotives. The modular scheme takes into the account factors affecting longevity and reliability of rails. Australian railways have already used super heavy load modular train with eight locomotives, distributed along the train (in other words they use eight modules), and 682 cars [8]. So the modular trains represent engineering approach which has already been implemented.