Section 1 Functions of Track Connection and Crossing Equipment
Turnout is a branch of connecting and crossing equipment, which enters or goes beyond another line from one line branch. Turnout is an important part of railway track structure.
The proportion of railway turnouts and lines in different countries varies greatly with the different railway volume and density. China is one of the countries with large railway volume and high density, so there are many railway turnouts in China. According to the statistics of 1997, there are nearly140,000 turnouts in China, with an average of per kilometer 1. 1 group, and the main line is per kilometer 1.8 group.
On railway turnouts, there are some complicated situations that are not found on ordinary tracks. For example, the fixed frog has broken rails, the impact angles of the switch rail, guard rail and wing rail are much larger than those of the curved rail, and the vertical and lateral rigidity of the rail in the turnout area is much higher than that of the ordinary rail. When rolling stock passes through turnout, the force between wheel and rail is much higher than that of ordinary track.
Therefore, the maintenance work of turnout part is more than that of ordinary track with the same length, and the service life of main parts of turnout is shorter than that of ordinary track. For these reasons, the turnout has always been regarded as the weak link of the track. Advancing is a main reason that affects the driving safety and limits the driving speed, and it is also the reason why we focus on the maintenance of the turnout.
Section 2 Turnouts and Cross Classification
Railway turnout equipment includes turnout, crossing, combination of turnout and crossing and other track equipment.
Turnouts are divided into single-opening turnouts, single-opening symmetrical turnouts, single-opening same-side turnouts, symmetrical three-opening turnouts, asymmetric three-opening turnouts and nested turnouts. Intersections can be divided into two categories: right-angle intersections and diamond intersections.
The combination of turnouts and crossings includes crossing turnouts and crossing lines. Other track equipment includes track telescopic spacing adjuster and iron shoe stripper.
Section III Development of Railway Turnouts in China
Before liberation, the turnouts used in China railway mainly depended on imports. In the early days of liberation, there were 300 kinds of turnouts in China. These turnouts are composed of 100 kinds of rails, and only 6, 7, 8, 9, 10,12, 15, 16, 24 and 65438 are single-opened turnouts.
For example, the No.8 turnout of 40B rail has many types, such as "old type", "new type", "experimental type" and "wartime type", which brings great inconvenience to the maintenance and replacement of the turnout. After the founding of People's Republic of China (PRC), China immediately set out to develop turnouts adapted to the specific conditions of China's railways.