68.  Q. What is a vacuum relief valve?  What a cylinder relief valve?

A. A vacuum relief valve is usually located on the steam chest or the live steam passage to the chest and opens when steam is shut off and engine drifting, allowing atmospheric pressure to pass into the steam chest, closing when working steam.  A cylinder relief valve is a pop valve screwed into the cylinder head and set at high enough pressure so it does not open in ordinary service, but will open to allow water to pass out when the exhaust port is closed by valves; or on compound engines when the pressure in the low-pressure cylinder gets too high.

69.  Q. What would be considered a bad engine or tender truck wheel?

A. One loose on axle; having bad flat spots; very sharp flanges; bad sand spots; cracks shelled out; or other defect that would make the wheel unsafe.

70.  Q. What should be done if a tender truck wheel or axle should break?

A. Would place a piece of timber or rail across the tender, jack up the corner of the truck that is disabled chain it to the timber and fasten the timber at the other end to hold it so it would carry the disabled truck.  If it is possible to slide the wheel or truck, place a tie across the rail and keep the wheel from turning, then slide it to a siding.

71.  Q. What should be done if an engine truck wheel or axle should break?

A. Would block between the engine frame and truck frame over the good wheel on disabled side, swing the disabled corner of the truck to the engine frame with a chain.  Look out when crossing frogs that disabled truck does not leave the track.  With a broken flange, would block the wheel to prevent its turning and skid it to a siding.

72.  Q. What should be done for a broken tender truck spring?

A. Jack the tender up to where it belongs and put a block in place of the broken spring.

73.  Q. What should be done with a broken engine truck spring or equalizer?

A. For a broken spring, raise the front end of the engine and place blocks across the equalizers under the truck spring near the spring band.  For a broken equalizer, block on top of engine truck boxes and under truck frame.

74.  Q. What should be done if a driving spring hanger or equalizer should break?

A. Would block between the driving box affected and under the frame over it, using hardwood block or piece of iron.  Would also block the equalizer up to its proper position between the disabled end and the frame, or over the other end, as the type of spring rigging requires, to hold the equalizer level.  For a broken equalizer, would block on top of all boxes affected, would raise the engine by running the proper driving wheels upon an incline or wedge to lift the engine while other boxes were blocked; a re-railing frog comes handy for this work.

75.  Q. How can an engine be moved if the reverse lever or reach rod were caught at short cut-off by a broken spring or hanger?