Abstract
Longitudinal shock is a familiar but little understood railway problem. A theoretical understanding and practical investigation are described. Theoretical considerations contains seven sections. Fundamentals of impact and design of hydraulic buffers are described first. Effect of wagon configuration on impact, performance is then calculated. Fundamentals of train shocks describes linear spring theory, and its extension to non-linear shock absorbers for trains coupled without and with free slack. Effect of wagon configuration on train shocks is shown. The in-train performance of hydraulic buffers is analysed. Design of an American cushion unit is given. Experimental work is divided into two sections, titled impact and train shocks. The first section contains three subjections, consisting of impact tests with hydraulic buffers on block wagons, and on actual wagons, and impact, test of American cushion unit. The second section comprises five sub-sections. Run-in tests employed rake impacts as a simulation for train run-in. Results from these tests are analysed. Run-out tests used controlled shocks in a short, train to study run-out with various drawgears. Results of the run-out tests are analysed in the next sub-section. The final sub-section describes tests with 70 wagon trains. One train was fitted with hydraulic buffers and drawgear. The other train was fitted with hydraulic buffers and ring spring drawgear. Performance simulation for a hydraulic cushion unit is described. This mathematical model reproduces test results, and enables characteristics for a cushion unit under any condition of impact or train running to be calculated. The influence of brake performance on train shocks is discussed. Buffer performance during braking of fully fitted trains is analysed. The requirements for optimum design of shock absorbing systems, together with the requirements for smooth train operation and the influence of brake performance on train shocks are given in the conclusion.