7. Q. What does the black hand on each of the air gauges indicate?

A. The black hand on the large gauge indicates the equalizing reservoir
pressure; on the small gauge, brake pipe pressure.

8. Q. What pressure is usually carried in the main reservoir?

A. Ninety pounds in freight and 130 pounds in passenger service. But
where freight engines are equipped with duplex compressor governor, the
low pressure top is adjusted to ninety pounds and the high pressure top
to 130 pounds.

9. Q. What pressure is usually carried in the brake pipe?

A. Seventy pounds in freight and 110 pounds in passenger service.

10. Q. What must the air pass through in flowing from the main reservoir
to the brake pipe?

A. Through the automatic brake valve.

11. Q. Name the different positions of the automatic brake valve.

A. Release, running, lap, service and emergency positions. The brake
valve used with the E. T. and L. T. equipment has still another position
known as holding position, which is located between running and lap
positions.

12. Q. Name the different positions of the independent brake valve.