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Comeng Traction > Brake Equipment > Flashcards

Brake Equipment Flashcards

1
Q

What are the three types of braking systems on a Comeng?

A

Rheostatic
Electro-pneumatic
Automatic Air

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2
Q

What are the 3 primary functions of the Brake Controller?

A

Charge, apply and release auto air brake

Apply and release- or partially release EP brake

Control Rheostatic brake application

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3
Q

How many steps are there in EP and Rheo brake modes?

A

7

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4
Q

What does moving the BCH between these 7 positions do?

A

Sends electrical signals to each car on the train telling it to apply or release to a predetermined level

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5
Q

Which two steps are combined and what pressure do they have?

A

Positions 1 and 2

75 kPa

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6
Q

what is the ideal operating pressure in BP?

A

550 kPa

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7
Q

What is BP minimum reduction pressure?

A

50 kPa

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8
Q

What is BP full service reduction pressure?

A

380-410 kPa

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9
Q

What is EP step 1 and 2 BC pressure?

A

75 kPa

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10
Q

What is EP step 7 BC pressure?

A

250 kpa

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11
Q

What is BC emergency pressure?

A

275 kPa

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12
Q

Where does EP braking get its air from?

A

Main Reservoir

T Cars - Supplementary Res.

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13
Q

How does the brake controller work for EP braking?

A

There are three wires. Different combination of wires produce one of 7 signals, providing 7 steps of braking

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14
Q

What does the Seven Step Relay do?

A

In EP braking - Converts electrical signals into 7 equal steps of air pressure

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15
Q

How do you isolate the EP brake if it becomes defective?

A

Trip the EP brake circuit breaker

(tripping this means the Rheo brakes will not operate also)

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16
Q

How do Rheostatic brakes work?

A

Purely electric brake

Turns the traction motors into generators and dissipates the energy produced into resistor grids. This produces retarding effect.

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17
Q

What are the advantages or Rheo braking?

A

Cost effective

No wear on friction braking equipment

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18
Q

When does rheostatic braking become ineffective?

A

Below 10kmh it loses effectiveness

Below 5kmh not enough current to work at all

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19
Q

What is Brake Blending?

A

When the train speed drops below 10kmh the Rheo brakes becomes less effective and the EP brake begins to apply

This happens automatically

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20
Q

What is Holding Pressure?

A

A small amount of air maintained in brake cylinders, which holds the brake blocks/pads against the wheels without retarding the train.

It reduces the amount of time taken for the EP brake to apply during blending.

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21
Q

What is the Holding Pressure on a Westcode?

A

35 kPa

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22
Q

What is the Holding Pressure on a Knorr?

A

0 kPa

Because disc brakes work instantly

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23
Q

How does the Emergency Brake work?

A

When the BCH is put into Emergency the Emergency /exhaust Valve will open and the Brake Pipe pressure vents rapidly

Zero will be displayed on the Brake Pipe Guage

Max pressure in brake Cylinder will be obtained in 3 seconds

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24
Q

What are the 3 positions on the BCH when running the Automatic Air Brake?

A

RUNNING and RELEASE
Service zone (1-7) - applied
EMERGENCY

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25
Q

How does the Air Brake work?

A

Any reduction in Brake Pipe pressure causes brakes to apply and retard train

Brake Pipe pressure reduction communicates to the Triple Valve on each car’s brake unit

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26
Q

In RUN and RELEASE what pressure is the Brake Pipe charged to?

A

550 kPa

(there is zero pressure in brake cylinder)
(train will roll if SPB’s are released)

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27
Q

When BCH is placed into the Minimum Reduction position in Service Zone how much will the pressure in Brake Pipe reduce by?

A

50 kPa. (it will now be 500 kPa)

28
Q

When the BCH is placed all the way to Full Service what will the pressure be in the Brake Pipe?

A

380 - 410 kPa

29
Q

When the BCH is placed into Emergency what will the pressure be in the Brake Cylinder

A

275 kPa

30
Q

What components of the Brake Controller come into play when the Handle is placed to Emergency?

A

The Charging valve will close

The Emergency exhaust valve will open allowing Brake Pipe air to exhaust to atmosphere

31
Q

Where can an emergency brake be activated from?

A

From any cab on the train at any time

32
Q

When might the Automatic Air Brake system be used?

A

Conducting a Running Brake Test

For the training/assessing of trainees or drivers

Driver competence maintenance

Train faults affecting the EP braking system

33
Q

What are the two methods the Air Brake can be released?

A

Full Release

Partial Release

34
Q

When would you use the Full Release method?

A

When the brakes:

Are no longer required

Have been applied too hard for intended use and there is enough time to fully recharge before brakes are required again

35
Q

When would you use the Partial Release method?

A

During a Running Brake Test

When the brakes have been applied too hard and there is not enough time to release and recharge before the brakes are required again

36
Q

What is the Full Release Method?

A

Return BCH to RUN and RELEASE

Allow the BP to fully recharge

Reapply the brake once the system has fully recharged

37
Q

What is the Partial Release Method?

A

Return the BCH to RUN and RELEASE

IMMEDIATELY return the BCH to minimum service position

As brake cylinder pressure reduces, move the BCH further into service zone until there is an audible blow of air - then hold steady

Check that brake cylinder pressure is holding steady at desired pressure

Assess braking effectiveness of the train

38
Q

How do you ensure a smooth stop when using the Air Brake?

A

reduce the brake cylinder pressure to below 120kPa

39
Q

Which Comeng trains provide Wheel Slide Protection during Air Braking?

A

Westcode does not

Knorr does

40
Q

What are the limitations of the Westcode Air Brakes?

A

Because the air used is supplied from the auxiliary res - charged to the same level as brake pipe.

When Air Brake is applied air is depleted from auxiliary tank and is only replenished when the BCH is returned to RELEASE position

On Knorr’s air is supplied from main res.

41
Q

What are the components of the Brake Controller? (7)

A

Release Prevention valve

Regulating valve

Relay valve

Charging valve

Lock Out Magnet valve and Ball Check valve

Emergency Exhaust valve

Equalising Reservoir

42
Q

What does the Release Prevention Valve do?

A

Prevents main res. air flow to Regulating valve when BCH is in Service Zone.

This ensures Air Brake will only be released when the brake handle is in RUNNING and RELEASE

43
Q

What does the Regulating valve do?

A

Equalises air pressure between main res. and Equalising Res. between 380-410 and 550 kPa.

The resulting air pressure is then duplicated in the Brake Pipe by the Relay Valve.

44
Q

What does the Relay valve do?

A

Controls the flow of air into and out of the Brake Pipe to a pressure set by the equalising reservoir

45
Q

What does the Charging valve do?

A

Allows main res. air to flow to the relay valve to charge the Brake Pipe.

It is open in all positions except EMERGENCY

46
Q

What does the Lock Out Magnet Valve and Ball Check Valve do?

A

Prevents the simultaneous application of the Air Brake and the EP brake

47
Q

What does the Emergency Exhaust valve do?

A

Vents brake Pipe air directly to atmosphere when an EMERGENCY brake application is made.

48
Q

What does the Equalising Reservoir do?

A

Aids in the smoother operation of the Relay valve when exhausting Brake Pipe air to atmosphere when an automatic brake application is made

49
Q

What does the BVICS do?

Brake Valve Isolating Cock and Switch

A

Controls the flow of:
Main res. air to the automatic air brake valves in the brake controller

Electrical current to the EP and Rheo brake selector switches in the brake controller

Electrical current to the low-pressure flag and lock-out magnet valve

Electrical current to the door monitoring circuits of the blue saloon door closed lights

50
Q

What does the Brake Unit do?

A

Directs air into and out of the cylinders when signalled by the BCH

51
Q

What are the Brake Unit components?

A

Variable load valve
Restricted application limiting
valve and ball check valve
Seven step relay valve
Restricted application magnet
valve
Triple valve
Release ensuring valve
Bypass check valve
Hand release valve
Dump valve

52
Q

What does the variable load valve do?

A

Monitors air pressure in the air suspension system and adjusts braking according to load

53
Q

What does the Restricted Application Limiting valve and Ball Check valve do?

A

Allows 10% increase in brake cylinder pressure when using air brake (from 250 up to 275)

Also adjusts brake cylinder pressure during Rheo to a Holding Pressure (35)

54
Q

What does the 7 Step Relay valve do?

A

Converses electrical code signals from BCH into 7 equal steps of air pressure during EP braking

55
Q

What does the Restricted Application Magnet valve do?

A

Prevents simultaneous application of the EP brake while Rheo braking (M Cars only)

56
Q

What does the Triple valve do?

A

It is the main control valve of air brake system. Controls air flow from:

BP to aux. res. To prepare for brake application

Aux. res. To brake cylinders to apply brake

Brake cylinders to atmosphere to release brake

57
Q

What do the Release Ensuring valve and Dump valve do?

A

There to avoid possibility of sticking brakes

58
Q

What does the Bypass Check valve do?

A

Provides alternative passage for main res. Air to reach brake cylinders in certain conditions

59
Q

What does the hand release valve do?

A

Manual release of brake cylinder air pressure

60
Q

During EP braking where is air supplied from?

A

Main res. (Supp on T Cars) via 7 step relay valve

61
Q

During air braking where is air supplied from?

A

From Aux res. Via triple valve

  • to brake cylinders on a Westcode or Control res. on a Knorr
62
Q

What does the Aux res. Supply on each train?

A

Brake cylinders on a Westcode

Pre-control res. in a Knorr

63
Q

On a Westcode bogie how do you know the brake piston is applied?

A

Stainless steel collar visible

30 - 65 mm

64
Q

What braking systems does wheel slide protection operate on?

A

All position Knorr

Westcode:
EP
Rheostatic
Some Westcodes during Air braking

Not available on either in EMERGENCY

65
Q

How does wheel slide work?

A

Frequency generator monitors turning speed of axles and compares.

On T Cars - brake cylinder pressure is lowered until corrected

On M Cars - Rheo brake is cut out. Braking controlled by Ep. Then brake cylinder pressure is lowered as for TCars

Comeng Traction (16 decks)

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