Testing of composite brake blocks of the type LL

The aim of this paper is to compare the composite brake block LL with traditional cast iron type P used largely for freight wagons. Properties of friction materials of aforesaid block types have a significant impact on the braking of railway vehicles. The result is the evaluation and comparison of friction characteristics on the basis of braking distances for various speeds and weight of the wagon.

TESTING OF COMPOSITE BRAKE BLOCKS OF THE TYPE LL

The aim of this paper is to compare composite brake blocks of the LL type with traditional cast iron blocks of the P type used mainly for freight wagons.

The properties of the friction materials of the blocks have a significant impact on the braking of railway vehicles. The result is an evaluation and comparison of friction characteristics based on braking distances for various speeds and wagon weights.

1. INTRODUCTION

The demands on the overall operational reliability of railway vehicles are rising with the increase in the number of kilometres of newly reconstructed tracks and with the increasing operating speeds of new and upgraded vehicles. The basic condition for the safe operation of these vehicles is a reliable and effective braking system. Brake blocks are the most important part of the braking system, the aim of which is to create a braking effect through friction.

Cast iron is the most common friction material for block brakes used for freight wagons. With its properties, it meets the requirements for operating vehicles only up to a certain speed. The declining value of the block friction coefficient points to the inadvisability of using cast iron at higher speeds, as it induces an undesirable prolongation of the stopping distance and an increase in brake block wear. This unwelcome fact, as well as the high level of noise during braking, has evoked interest in the development and manufacture of new friction materials. A smoother wheel tread surface, better operating properties during braking, and lower noise emission values can be

Ing. Jozef Hriňák, University of Žilina, Faculty of Mechanical Engineering, Department of Transport and

Handling Machines, Univerzitná 1, 010 26 Žilina, Slovakia. Phone: +421 41 513 2679. (…)