The results of the studied cases show that in towing case critically high longitudinal forces can occur in the couplers, especially in the interface of the two trains and within the defect MU. The critical situation arises at sudden changes from traction to braking and vice-versa. Reason therefore is a insufficient design of the couplers for pulling solicitations and the potential appearance of essential displacements between the wagons in towing case which leads to a 'snatch-effect'. The combination of elder and new trains can be worse than that of two older trains and the forces increase with decreasing of the preload in the new-type couplers. The worst situation occurs in case of two new trains with couplers of too low pre-load. Both coupler types are affected:- older-type: longitudinal very elastic train by soft rubber elements in the couplers - new-type: longitudinal very stiff train and gas-hydraulic device with defined pre-load. The new-type coupler is only affected, if it's preload is too low. Increasing pre-load of the gas-hydraulic cartridge beats down the maximal forces beneath the limits without noteworthy loss of crashworthiness or other disadvantages. In between some coupler manufacturers designed couplers with bi-directional acting dampers. This should be favourable to the towing case but simulations are still necessary to prove it. The presented method of calculation and simulation of the towing or pulling case shows the necessity to check the suitability in the design phase, in order to avoid huge retrofit costs, but also to inspect or scrutinize old stock.
Behaviour of motor unit couplers in towing case
Verhalten der Kupplungen von Antriebseinheiten im Zugfall
2003
10 Seiten, 9 Bilder, 1 Tabelle
Aufsatz (Konferenz)
Englisch