STEAM LOCOMOTIVE ENGINEMAN’S. Manual - part 29

Chapter 13: - General Westinghouse Brake – Questions and Answers

CHAPTER 13

GENERAL WESTINGHOUSE BRAKE – QUESTIONS

AND ANSWERS

What is the purpose of the main reservoir?

It is for the purpose of storing a volume of air at a sufficiently
high pressure to release the brakes and to recharge the train
pipe and auxiliaries.

Why is it essential that the reservoir be kept free of
water?

When water accumulates in the main reservoir it reduces the
volume available for the storage of air, and consequently,
when the brakes are being released, the reservoir is taxed to
a greater extent. This causes a longer time to be taken to
recharge a long train line, and throws extra work on to the
pump.

From where does the water found in the main reservoir
come?

It is drawn in with the air from the atmosphere and is
deposited when the air cools.

What defects would reduce the capacity of the pump?

Restricted passages to the receiving valves, and from the
discharge valves to the main reservoir.

Air strainer blocked up.

Receiving and discharge valves and their seats defective, or
the valves not having the correct lift.

What defects in the steam end of the pump would cause
the pump to be slow in operation?

Badly worn main valve piston rings, slide valve, and the
steam piston will reduce the speed of the pump. Lack, of
lubrication, or the main steam valve from the boiler and the
governor steam valve restricting the flow of steam will also
reduce the speed.

Chapter 13: - General Westinghouse Brake – Questions and Answers

What could cause the pump to make irregular strokes?

Receiving or discharge valves defective or broken.

What would cause the pump to “jiggle and dance”?

Usually the result of a badly worn reversing valve or its seat.

What causes the pump to “groan”?

Lack of lubrication, inferior oil to the main valve and steam
and air cylinders, a bent piston rod, or the piston glands
being packed too tightly.

What are the causes of the pump running hot?

Excessive working due to leakages, defective air valves and
their seats, worn piston rings, racing the pump, incorrect
lubrication, and the pump working constantly against high
pressures.

What causes the pump to pound?

The pump being loose on the foundation brackets, the air
piston being loose on the rod, badly worn air valves causing
too much lift, or excessive lubrication.

What examination should be made if the pump stopped?

Check up on the lubricators to the steam and air end, and
examine the glands of the pump.

Close the steam valve and allow the steam in the pump to
condense, give more oil through the lubricators and then
open the steam valve quickly. If the pump does not respond,
close the steam valve and shut off the lubricator. Take the
cap off the reversing valve chamber and open the steam
valve to note whether a full flow of steam is reaching the
pump.

Close the steam valve again and note the condition of the
reversing valve and whether oil is present in this chamber. If
not, give a small amount of oil, replace the cap, and again
turn on the steam quickly. If there is not response, the main
valve should be examined to note if the slide valve is broken
or displaced, or if it’s connecting pin to the main stem is
jamming.

Chapter 13: - General Westinghouse Brake – Questions and Answers

Check up on relief port blockage on the outside end of the
small piston and, in this case, ease back the ends of the
cover studs to release any back pressure. The reversing rod
may be bent or broken, the reversing plate on the main
piston may be displaced, the nut may be off the bottom of
the air piston or a piece of broken air valve may be under the
air piston, preventing the piston from completing its stroke.

What would be the effect if the pin valve port became
blocked up?

Main reservoir pressure from the central chamber could not
pass on to the top of the governor piston when the standard
main reservoir pressure was reached, consequently, the
piston and steam valve would remain up in the open position
and allow steam to pass to the pump, keeping it working until
the main reservoir pressure was almost equal to boiler
pressure.

If the pin valve passage was blocked, how could the
main reservoir pressure be controlled?

By operating the steam valve to maintain the main reservoir
pressure at approximately 90 lb per square inch.

What would be the effect if the pin valve was stuck in
the open position, due to damage or dirt on the seat?

It would cause a continuous escape of air from the vent port
and, if the air could not escape fast enough, it would build up
a pressure on top of the governor piston, forcing the piston
and the steam valve down and cutting off the steam to the
pump.

What should be done if the pin valve port remains open?

Cut out the governor by blind jointing the air pipe at the
governor connection, and control the pump with the steam
valve.

What would occur if the strainer in the air pipe to the
governor became blocked?

Main reservoir air could not enter the governor and the pump
would continue to work until the pressure was almost equal
to boiler pressure.

Chapter 13: - General Westinghouse Brake – Questions and Answers

What action should be taken if the strainer becomes
blocked?

Control the pump with the steam valve until an opportunity to
clean and free the strainer presents itself.

When should air escape from the vent port?

Only when the main reservoir pressure becomes slightly
greater than the setting of the regulating spring, viz 90 lb
pressure.

What would be the effect if the drain pipe attacked to the
chamber under the governor piston became clogged up,
and steam leaked past the valve and bushing into the
chamber?

The governor piston and steam valve could not be forced
down, and the pump would not stop working until the main
reservoir pressure was almost equal to boiler pressure.

What would be the effect if the drain pipe attached to the
chamber under the governor piston became clogged up,
and steam leaked past the valve and bushing into t he
chamber?

By uncoupling the pipe at the governor connection. The pipe
should be attended to when the locomotive returns to Box
Flat.

`What would be the effect if the vent port became
blocked up?

The pump would be very slow in starting after once having
stopped.

Why?

Because main reservoir pressure above the governor piston
would have to escape by way of leakage past the governor
piston to release the air from this chamber.

How should a blocked vent port be remedied?

Clear the port through the plug with a very fine wire and
kerosene. If this is not successful, slacken back the plug to
cause a leakage of air past the plug threads.

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