LHB coaches have been introduced in services on some of the premier trains on Indian Railways state art features.One of the important feature provided in these coaches are Initially, coaches turned out by production units were having two types of WSP’s namely supplied by (a) M/s Knorr Bremse India limited & (b) M/s SAB WABCO India Ltd. During initial supplies, Parrizi type processor was received with M/s Knorr Bremse air brake system whereas Sab Wabco with its own.During further developments, railways started using processors manufactured by M/s Knorr Bremse with its own air brake system & in the meantime, M/s Faiveley has taken over M/s Sab Wabco. Therefore, presently railways is having two types

  1. M/s Knorr Bremse India Ltd.
  2. M/s Faiveley India Ltd. (earlier known as M/s Sab Wabco)

WSP control unit is a combination of various electronic cards.This unit is housed in electrical control panel units. This unit is connected by means of various cables through various equipment

Working Principle:

During the course of brake application, there are possibilities of skidding/sliding/locking of the individual axle. In these cases, adhesion between the rails & wheels plays the vital role. Above situations are likely to cause damage to wheelsets with increased braking distance. The main purpose of using the WSPs is to utilize the available adhesion. The WSPs provided in the system avoids wheel sliding, also cuts the maintenance cost. Speed sensors, the part of the system detect the speed of the wheel & sends the signal to the processor unit.
The processor unit evaluates the received signal from speed sensor of the vehicle & generates signals enabling the dump valve/antiskid valves to control the brake cylinder pressure in case of any locking/skidding. The control on the brake cylinder pressure is instantaneous to the wheel to rail adhesion, keeping
the wheels within their optimum range of skidding.

The WSP has some of the major parts:
  1. Speed Sensor
  2. Phonic wheel
  3. Microprocessor
  4. Dump valves
  5. Pressure switch