203. Q. What effect has piston travel on the pressure developed in the brake cylinder?
A. The longer the piston travel the greater the volume or space to be filled with air; therefore the lower the pressure.
204. Q. When should brakes be tested?
A. Brakes should be tested before leaving a terminal and after any change in the make-up of the train, at all designated points, also, whenever the engineer is in doubt as to his having the control of all brakes.
205. Q. How should a terminal test of the brakes be made?
A. After the pressure is pumped up, a reduction of about ten pounds should be made and the length and force of the brake pipe exhaust should be noted, also the manner in which the exhaust closes; then a further reduction of ten pounds should be made and the brake held applied until signaled to release.
206. Q. If, when making a service application of the brake, the brake pipe exhaust closes suddenly and then begins to blow again, what does it indicate?
A. That the brakes, or at least part of them, have applied in quick action.
207. Q. What is meant by a running test, and when should this test be made?
A. A running test is made while the train is in motion, and steam is being used, when a sufficient reduction should be made to apply all brakes. After noting the efficiency of the brakes they should be released. Running tests should be made following all standing tests and at all other points on the road as required by the rules.