• EMU is provided with air brake system.
  • This system is operated by electro pneumatically EMU is provided with air brake system.
  • This system is operated by electro pneumatically(EP brake system) and through direct reduction of  BP also (auto brake system).
  • BP pipe is also running throughout the formation and all the Angle cocks in between the coaches are to be kept open for the BPcontinuity.
  • BP charging is done from the leading motor coach by turning on BIV key.
  • Underneath of each driving cab, an equalizing reservoir is fitted and under each coach, an auxiliary reservoir for storing 5 kg/cm² of BP pressure for application of Auto Brake is also fitted.
  • All coaches are fitted with an EP unit under the bogie frame for brake application When BP charged in the whole system BP pressure will charge in all EP unit and auxiliary reservoirs and kept ready for EP and Auto brake application.
  • Each motor coach and Trailer coach is provided with eight brake cylinders in EMU and each trailer coach is provided with four brake cylinders in MEMU.
  • Brake cylinder pressure is set at 1.5kg/cm² for motor coaches and 1.8 kg/cm² for trailer coaches.
  • All trailer coaches are provided with brake cylinder pressure gauge under the bogie frame.
  • In every coach one EP isolating cock (EPIC), one auto isolating cock (AIC), and two bogies isolating cock (BIC) one for each bogie are provided.
  • For manual releasing of the brake, each coach is provided with a release valve, which can be operated from either side of the formation ( BRH ).
  • In every driving cab, a duplex gauge indicating MR and BP pressure one brake cylinder gauge and a BP pressure gauge for the guard are also provided.An emergency brake valve guard is provided in every driving cab.
  • Braking of EMU is effected by the brake rigging arrangement by wheel clasping or gripping by brake blocks both sides.
Westinghouse Brake System (WSF):

The parts of the brake controller are

  1. Brake controller handle
  2. Self-lapping cylinder
  3. Puppet valve group, (A, B, C & D)
  4. Equalizing discharge valve
  5. Pressure reducing valve
  6. Equalizing reservoir
  7. Brake isolating valve switch key operated.
  8. Application and holding contacts.

The parts of the EP unit are

  • Holding magnet valve HMV
  • Application magnet valve AMV
  • Limiting valve
  • Triple valve
  • Positive acting check valve
  • Stabilizing valve with bulb
  • Safety valve

When the brake controller handle is in the release and Running’ position, Application and holding contacts in the brake controller remains open.In the puppet valve grouping, valves A & B remain open and C and D remain closed when BCH in release and running position. As soon as BIV key is turned ON, MR pressure will admitted to the limiting valve and reduced to 5 kg/cm², and sent to puppet vale B & A.

Through B valve, MR charges the equalizing discharge valve top chamber and equalizing reservoir.Through a valve, MR charges the equalizing discharge valve bottom chamber and charges the BP pipeline throughout the formation provide all end cock are in the opened condition in between coaches.

Since equalizing discharge valve top and bottom chambers are charged with 5 kg/cm², the valve is balanced and closing its exhaust port.And BP pressure is maintained at 5 kg/cm². The brake pipe pressure charges the triple valve provided all AIC are in opened condition BP pressure charges triple vale both chamber with 5 kg/cm² (now the triple valve is balanced) and also BP charges the Auxiliary reservoir, triple valve stabilizing valve and stabilizing valve bulb. Now the entire formation is charged with BP pressure and ready for brake application.

EP Application:

When the driver’s brake valve handle BCH moved between position I and II electrical contacts are made which energize the holding magnet valves of the E.P brake units this closes the exhausts from the brake cylinders.

The application valves are next energized and MR pressure flows to the brake cylinders. The driver’s brake valve contains a self-lapping device so that brake cylinder pressure is built up to a value proportional to the angle through which the handle has been moved.

A series of small angular movement of the handle from the position I will apply brakes in steps until maximum brake cylinder pressure is reached in position II. In the same way, the brake may be released in step by moving
the handle towards position I, the brake cylinder pressure drops in each step being proportional to the angle through which the handle has been turned.

In addition to the self-lapping contacts of the driver’s brake valve, positive acting contacts make the direct connection to the application and holding circuits in the full and emergency application. BCH moved to full EP application position maximum brake cylinder will reach i.e. 1.8 Kg/cm2 for trailer coach and 1.5 Kg/cm2 for the motor coach.

EP Release:

When the brake controller handle is moved back from full EP position towards release and running position in the self-lapping range, first, the application contact gets opened, thereafter holding contact opens, de-energizing both the application and holding magnet valves of all EP units, when the holding magnet valves are de-energized, brake cylinder pressure is exhausted to atmosphere through G valve of the triple valve and exhaust port which is opened when holding magnet valve de-energizes.

When the brake cylinder pressure reduces correspondence to the angular displacement of the brake controller handle, the holding contact closes again energizing the holding magnet valves of all the EP units and closing the exhaust port of all brake cylinders.

Thus the partial release of EP brake is possible. When the brake controller handle is moved to release and running position (Position-I) the holding contacts open de-energizing all the holding magnet valves in the EP units in the formation by opening all the exhaust ports of all brake cylinder. The brake cylinder pressure is fully released into the atmosphere.

The action of triple valve stabilizing valve:

When EP brakes are released, the brake cylinder pressure is exhausted to the atmosphere through the G value of the triple valve and exhaust. If G valve of the triple valve remains closed due to any reason for EP brake application, brakes cannot be released.

To achieve EP brake release by restoring triple valve diaphragm to its normal position, the stabilizing valve is provided. During application, the air pressure in triple valve stabilizing valve bulb is exhausted to atmosphere, through the exhaust port in the central stem of the triple valve-stabilizing valve.

When EP brake is released fully stabilizing valve bulb connects to the auxiliary reservoir and resulting in the reduction of auxiliary reservoir-pressure and allow the triple valve to move to the correct release position.

Auto Brake Application:

The automatic brake is controlled by air pressure and does not depend on any electrical supply. The application is made by reducing the pressure in the brake pipe which is made by reducing the pressure in the brake pipe before an automatic application is made the driver’s brake valve handle should be moved quickly to position III (Lap) and when the application is to be made, to the position IV.

In position IV pressure in the equalizing reservoir is reduced; this reduction is reproduced in the brake pipe by the equalizing discharge valve. The reduction in BP pressure operates the triple valves on each EP unit, which in turn connect the auxiliary reservoirs to the brake cylinders.

Movement of theBCH to lap will arrest the BP pressure and no further application of brakes. If the handle is moved from lap to application and back again to position lap repeatedly the automatic brake will apply in steps. The automatic brake is not provided with graduated release Emergency ApplicationBCH moves to emergency position an emergency application of EP and auto brakes come together. EP brake will come only if EP supply is available.


  1. Step by step application of both EP and auto brakes is possible.
  2. Step by step release of EP brakes is possible.
  3. Step by step of release of the auto brake is not possible.
  4. During auto application BCH should not be brought back to normal or to the self lappingrange as the release of auto brake take place and the train may go out of control.
Dead Man Valve ( Dead Man’s Handle) :
  1. Each master controller is fitted with the pilot valve, which opens when the master controller handle is released in an operative position.
  2. When the driver becomes incapacitated and releases the master controller handle, pilot valve will open the emergency application valve, which in turn vents the brake pipe and makes an emergency application of the auto brake.
Procedure for operating parking brake:
  • Ensure MCB for EP Brake Supply 5A and MCB fault indication 5A are in good condition.
  • BL key to be unlocked / “ON” position.
  • Ensure Parking Brake switch in the BL box, the 2nd row which is painted with Yellow color is in ‘OFF’position (Normal position – Downwards).
  • Before taking traction, ensure the Parking Brake lamp is in extinguished condition.
  • Operate Parking Brake BL switch to ‘ON’ position (upward) and ensure the healthy condition of parking Brake by hearing the “hissing” sound of Rotex magnet valve and reduction in ParkingBrake pressure from 4.0 Kgs./Cm2 to 0 Kgs./Cm2 in Parking Brake pressure gauge and also ensure glowing of Parking Brake Red Lamp. Again bring back the switch to ‘OFF’ position (Down Wards).
  • Parking brake controls wheel No.1&4 in leading bogie, 5&8 of trailing bogie of Motorcoach inMEMUs and trailer ‘D’ coach in modified EMUs.
  • Ensure simultaneous application.
  • Ensure mechanical release lever (painted in Yellow) is in normal position (6o clock position).
  • Ensure Parking Brake cut-out-cock two Nos. (painted in Yellow) provided below the MCB control panel is in open condition in MEMUs and in modified EMUs it is provided under neath of trailer‘D’ coach.
  • Before applying Parking Brake, first, secure the train with auto brakes/ EP brakes and ensure RBC raises to 1.6 Kgs./Cm2.
  • Four Parking Brake cylinders are provided in each motor coach and brake will be applied on wheelNo.1, 4, 5 and 8 when Parking Brake is applied.
  • When the Parking Brake cylinders are not released trough BL switch, manually release the pressure through Parking Brake release handle provided for it and ensure proper releasing of Parking Brake, before starting the train.
  • Whenever the Parking Brake is in applied position or not released properly, the Motorman will experience hard pulling while starting the train.
  • Even after the Parking Brake is in the released condition, if MSTWL is glowing, bye-pass the ParkingBrake governor switch located in switch panel on Motorman’s side.
Conditions for applying Parking Brake:
  1. When there is no OHE supply for more than 10 minutes.
  2. Prolonged detention of rake (Train) in the gradient section.
  3. On physical stoppage of the train with EP/Auto application (BC pressure 1.6 Kgs./Cm2) for the stabling of formation at Shed or at the siding.
  4. Convey and confirm with guard through bell code (00000 PAUSE 00000) before applying and after releasing the Parking Brake.
  5. While releasing the BL key (BL box locked), Parking Brake will apply automatically where the parking brake provision is made.
  6. On unlocking BL key from the other cab, Parking Brake releases where the parking brake provision is made




  1. Check the MCB for E.P.Brake; E.P.Auto Switch; E.P.Supply switch is in ‘ON’ position.
  2. If found ‘OFF’ put it to ‘ON’.
  3. Ensure BIV is in turn ‘ON’ position.
  4. Re-check for the proper working of E.P. Brake.
  5. Replace EP unit with overhauled one.