Pneumatics Flashcards
What equipment runs on compressed air? (7)
Main Reservoirs
Auxiliary Reservoirs
Air Suspension Reservoirs
Surge Reservoirs
Whistle
Friction brakes
Spring Park brake
What pressure does the Compressor Governor / Compressor Pressure Switch maintain the Main Reservoir at?
850 - 1000 kPa
What pressure are the Safety Valves set at?
1100 kPa - between compressor and air dryers
1050 kPa - between air dryers and Main Res.
What happens if the Compressor Pressure Switch (CG) is isolated?
The air compressor will run continuously
What is the air suspension system made up of? (3)
Levelling valves
Air bags
Surge reservoirs
What do the Levelling Valves do?
They Inflate or deflate air bags according to passenger load
On DM Cars: One on each bogie.
On T Cars: Two on No.1 Bogie, 1 on No.2 Bogie
What happens if air bags fail?
There is a spring system as well.
What do the Surge Reservoirs do?
Supply air to the air bags to compensate for:
Train tilting around corners
Uneven passenger load
Sudden imbalance in suspension system
Two surge res. per bogie
What is the Brake System comprised of?
Service Brake (Friction
Holding Brake
Emergency Brake
Park Brake
What is the Service Brake made up of?
ED
EP
When does the ED Brake work?
Normally, above 10kmh
Between 5-10kmh. brake blending occurs
What happens during wheel slide?
ED brake drops out and EP brake takes over
What is the EP brake used for?
Stopping at low speeds when ED brake fades out
Assisting ED brake during heavy high-speed braking
Supplementing braking demand when effort provided by the ED system is insufficient
What happens if ED brake fails?
EP brake will automatically take over
What kind of brakes are on TCars?
EP brakes only
When does the Holding Brake apply?
when MCH is in 0 (coast) when train is stationary.
What is Holding Brake pressure?
110 kPa (+/- 30 kPa)
When does Holding Brake pressure release?
When traction power is applied
What happens if train is stationary and and a different braking position is selected (B1-B6)
The corresponding braking pressure will be applied
What is B6 (Full Service) pressure?
189 kPa
What is Emergency pressure?
280 kPa (+/- 30kPa)
What is Main Res operating pressure?
850-100 kPa
What happens if MCH is moved to B1, B2 or B3 when the train is on a gradient?
B1-B3 pressure are below Holding pressure so the train may roll
What must you do with BCH when moving between braking and powering?
Remain at ZERO/COAST for 1 second to allow TCU/BCU time to set up
What fault lights come up when Service Brake is applied?
Maintenance Fault Light
General Fault Light
They will flash and should not be considered a train fault
What brakes are used during emergency braking?
Friction brakes only
When do SPBs apply?
Automatically when Master Key is turned to OFF
Automatically applies when Main Res. pressure falls below 350 kPa
Park Brake Switch in drivers cab illuminates if one SPB is applied
Where are SPBs located?
Wheels 3 and 7 on every car
Can SPBs be manually released?
Yes
Manual release device located on each side of every bogie
Which SPB is locked?
Number 1 Bogie
What happens if the SPB is applied with the train speed over 5kmh?
Safety Loop will de-energise and emergency brakes will apply
Reset Safety Loop by placing MCH into ZERO
What is procedure to manually release SPB?
Isolate the Bogie
Pull the handle to release SPB
Reinstate Bogie
How does the Brake System work?
MCH sends electrical signal to BCU which then processes input and applies/releases brakes through the Brake Module on each bogie accordingly
What does the braking system consist of? (5)
BCU (one per car)
Brake modules (two per car)
Brake Cylinders (every wheel)
Parking Brake Cylinders (Wheels 3 and 7)
Associated ICs
What does the BCU do?
It’s an electronic microprocessor that receives and interprets signals from various sources to determine ED/EP braking requirements
How are BCUs on DM different to those on TCars?
DM BCUs operate in conjunction with TCU
On trailer cars, there is no ED braking and no TCU
What information does the BCU use to work out braking requirements? (4)
Load/weight (from secondary suspension)
Speed (from pulse generators on each axle)
ED brake information (from TCU on a DM car)
Wheel slip protection
Which isolating cocks do we need to know in the Brake Modules ?
Top - air suspension
Bottom - bogies
How does the TCU manage wheel slip?
When ED braking effort falls below 90% TCU drops ED and EP takes over
Sanders automatically dispense
How do you reset EP to ED during wheel slip?
If safe, move MCH to 0 or a powering position for one second then return to desired braking position
What is each sand box equipped with?
Padlock
RED LED illuminates if sand is below 20%
White manual test button
Sight glass to see dryness of sand
When do sanders operate?
Only during EP braking
Not powering or ED
What speed do sanders operate at?
Stop working below 5kmh
