390 Theory - Braking Systems

What brake control systems does the 390 use?

Dynamic Braking

Friction Braking

Blended Braking

Dynamic Braking

Converts trains energy (when braking) back into electricity using:

Regenerative or Rheostatic braking

Regenerative braking

Diverts the braking current (electricity) to the overhead line

Rheostatic braking

Diverts the braking current (electricity) to the resistor grids on the roof and coverts it into heat to be cooled by the the cooling fans.

Blended braking

Use of both Dynamic braking and Friction braking

Friction Braking

Uses cast iron, axle mounted brake discs on all bogies

What brake system is used when the train speed is below 25mph

Blended: both Dynamic braking and Friction braking

What brake steps uses Dynamic braking

Steps 1 and 2

What brake step uses Blended braking?

3 and above

What is experienced when braking at step 3 and above

Blended braking

WSP - Wheel Slip Protection

Why are the leading axles automatically isolated in EP brake mode?

Maintain steady speedometer reading and prevent loss of TASS during WSP

However:

If emergency brake application initiated, or

in Brake Pipe Mode

The brake functions normally on the lead axles

Variable load braking

Devices measures the load of passengers in each coach

Braking effort is automatically adjusted proving right amount of braking force for each coach

Vehicle passenger overload

• Vehicle overload lamp - illuminate red

• TMS screen 7:

  • Green bar = below 175%

  • Red bar = above 175%

• Overload can only be in coaches B, C, D, F, G

You Must:

• Temp iso Tilt

• Inform Signaller and AWC Control

When must the emergency plunger be used?

Brake control failure

Severe WSP activity - train unlike to stop short of BOTS

(Buffer stop, Obstruction, Train, Signal)

What is a Brake Continuity Circuit?

Proving circuit running around the whole train from front cab to rear

What happens if the Brake Continuity Circuit is broken?

The brakes will automatically apply

What actions can brake continuity?

• Door Interlock Circuit Lost

• BIC isolated

• Parking Brake Application

• Passenger Alarm Handle Operated (Passcom)

• Emergency Egress handle pulled

• External Step extended

• Low Main Air Pressure (5.5 bar)

• Loss of feed to any brake control computer

• Tilt System Major Failure (Hard Tilt Failure)

What are your actions if there is a unidentified fault in the continuity circuit? and Why?

Use the Service Brake Fault Override switch

Energises a second continuity circuit - if the fault clears the service can continue

Brake Continuity Isolation switch - What does it do

It is used to create a continuity circuit around the leading cab only

Egress and Passcom will still be active on the train

Emergency brake in the rear cab and TM office will not be active

What must you do if you use the BCI switch in service?

Stop

Contact the signaller immediately

Follow signaller instructions

Inform TM

Take the train out of service at the next suitable location

Can Train enter service with BCI operated?

No

What are you actions if the BCI switch does not solve the fault

Brake Pipe Mode

What is Brake Pipe Mode

It activates the TM and Rear cab emergency plungers

50 mph max speed

List the steps needed to enter brake pipe mode

1. TBC to step 6

2. Select Neutral (ensure interlock)

3. Brake Control Switch to ‘Brake Pipe This Cab Charged’

4. Select forward

5. TBC to off

6. TBC slowly back to step 6, observing brake gauge rising to 3.4 bar.

7. TBC then moved through brake steps to step 1 or 2 observing brake gauge falling/rising to prove brake pipe has set up correctly.

8. Continuity Test required.

Describe a Brake Continuity test

• The Train Manager will go to the rearmost cab and contact the driver via the cab to cab comm’s.

• Driver selects brake step 2 on the PBC and states ‘ready for continuity test’.

• TM in rear cab presses the emergency plunger and leaves depressed for 40 seconds.

• Driver in front and TM in rear observe brake gauge go to zero.

• After 40 seconds and both gauges reading zero, the TM resets the plunger and both see the brake gauge rise.

What do Pneumatically Flag indicators indicate?

• Left and Right flag: Air contained within the Brake Cylinders

• Middle flag: Parking Brake Released

Red = On

Green = Off

What is in the External Pneumatic Cupboards?

Left cupboard:

• ASIC Air Suspension Isolating Cock

• BCIC 1 & 4 (Brake Cylinder Isolating Cock) - right flag

• BIC Brake Isolating Cock

Right cupboard:

• PBIC Parking Brake Isolating Cock - middle flag

• BCIC 2 & 3 (Brake Cylinder Isolating Cock) - left flag

What happens if the BIC is operated?

Breaks continuity

Brake fault lamp illuminates

BCI switch must be used

Rotational test

What happens if the BCIC is operated?

Air is vented from cylinders

Flags turn Green

Rotational test must be done to confirm brake release

Parking Brake Isolation procedure

To manually release a Parking Brake proceed as follows:

• Operate the Parking Brake Isolating Cock (PBIC) to release the air (A side).

• Release retaining clip and withdraw locking pin  (B side)

• Pull the handle to its fullest extent (approx 1 inch)

• A ‘clonk’ should be heard when each cable is pulled as the spring releases.

• Push handle back into its housing and replace locking pin.

This must be done on BOTH axles of the affected bogie.

• Carry out a rotation test to prove that the parking brake is released.

• The centre brake flag will remain RED after isolation.

• Operate the BRAKE CONTINUITY ISOLATION switch in the cab (or brakes will apply above 3.5mph).

• (Under instruction) Select ‘BRAKE PIPE THIS CAB CHARGED’ on the BRAKE CONTROL switch and set up Brake Pipe Mode (Max 50mph)

• The PARKING BRAKE APPLIED lamp remains lit in the cab.

• Unit MUST be taken out of service at the next suitable location.

What is the SIFA valve

The SIFA valve is a Brake Pipe Emergency Vent Valve

It is connected to:

• Pass Comm’s

• Emergency Egress

• Door Interlock

• Low main air protection

What must you be aware of if the SIFA valve is isolated?

1. ALL safety systems are bypassed.

2. Ensure that all external doors a fully closed and ALL four Crew Access Doors are locked.

3. Ensure ALL four TAD’s are retracted.

4. Ensure ALL external Parking Brake indicators are Green.

5. The 390 Driver must ride in the rearmost 390 cab to monitor the Main Air pressure. Ensure that it does not fall below approx 5.0 BAR.

6. WSP is removed