necessary to disconnect the valve stem nor to clamp the valve; the valve will get the eccentric movement, but the port opening will be reduced and be closed in any cut-off shorter than about 50%.

Q. 5.-Suppose the combination lever breaks very close up to the bell crank, how should one arrange?

A.-In that case remove the union link and the broken piece of the combination lever, secure the valve over the ports as has been described, disconnect the valve rod and tie up the loose parts to keep them from doing damage. Proceed under power of the other side of the engine.

Q. 6.—If the valve rod should break, what should be done?

A.-Block the valve by tightening the set-screw on the valve-stem crosshead as already understood, and either disconnect the broken valve rod from the combination lever, or tie it up in such a manner that it can swing to the motion of the combination lever without striking anything, and go on with the engine working on one side.

Q. 7.—If the vertical arms of the bell crank should get broken, what would be the best thing to do?

A.—The valve rod should be disconnected from the combination lever, and as the latter is carried by the vertical arms of the bell crank, the union link and combination lever must be taken down; the valve should

be centred and secured in the prescribed way, and you can then proceed-on one side.

Q. 8.-In these cases of failure of certain parts of the gear such as the eccentric rod or unión link, etc., what are the advantages in being able to still secure the short movement of the valve and a limited port opening when the piston is at the beginning of its stroke?

A.—On the big up-to-date engines it is impractical to try to remove the main rod in cases of breakdowns, and when it is left up and the valve is blocked at the centre of its travel, the piston will meet with high resistance toward the finish of either stroke, on account of the air compression ahead of the piston and a partial vacuum behind it; this added to the braking power at applications of the air brake may cause the drivers to slide and flatten. The port opening provided as referred to, gives relief from this effect; further, it permits oil from the lubricator to reach the cylinder and prevent the walls from becoming dry and being cut by the piston—a condition that must be particularly guarded against when the main rod is left up, in cases of breakdowns.

INDEX

ACCESSIBILITY of Walschaert gear, 131, 132
Adaptability of Walschaert valve gear, 142, 143
Adjustment of Walschaert valve gear, 102
Advantages derived from the use of Walschaert gear, 129–148
Allan valve gear, and the Allen valve, 102
Analysis of the Walschaert gear, 11-92

B
BAKER-Pillion improved valve gear, 228

Advantages in securing the short travel of the valve on

disabled side of engine, 236
Combination lever, if broken short, how arrange, 235
Eccentric crank or eccentric rod, if broken, what should

be done, 233
Engine disabled on one side, how to block the valve, 233
Other breaks requiring bolting bell crank to frame, 234
Questions and Answers on break-downs, 233 to 236
Valve events in general, 230 to 232 inclusive
Valve rod, if broken, how repaired on the road, 235
Vertical arms of bell crank, if broken, what is best to do, 235

Union link or crosshead arm failure, what to do, 234
Baker-Pilliod valve gear, 222 to 236 inclusive

Original style with outside admission, 224

With inside admission, 228
Baldwin engine with Walschaert gear, 65 to 67 inclusive
Belgian engine with Walschaert valve motion, 80 to 87 inclusive
Bent piston rod in connection with preceding accident-should

main rod be left in place? 182, 183
"Blocking the valve"-what is meant, and how it is done, 171

to 174 inclusive

Breakage of lower section of combination lever, or its link to the

crosshead, 180
Break-downs on the road. Difference in methods of disconnec-

tion of Walschaert and Stephenson gears, 170, 171
Broken radius-rod hanger, 178, 179
Broken valve-stem, 179, 180
Building up the Walschaert gear: The start, 28
Built-up Walschaert gear complete, 42

Case of broken or detached piston—what to do, 182
Checking dimensions of the gear, 98 to 100 inclusive
Combination lever, 29
Combination lever (lap and lead lever) for inside admission valves,

196
Combination lever (lap and lead lever)—to determine proper

proportions of: for outside admission valves, 195
Comparative weights of Walschaert and Stephenson valve gears,

133 to 138 inclusive
Confusing in the meaning of lead, 158
Connections of the eccentric rod, 43
Constant lead with reverse lever in any notch, 38
Continuing the layout of the gear, and formulas, 105 to 109

inclusive
Correcting the built-up motion, 40, 41
Correction of one error introducing others, and their relief, 167
Could a broken side rod totally disable an engine with Stephenson

valve motion? In cases of break-down requiring valve block-
ing should valve-stem of the Walschaert gear be disconnected?

De Glenn compound engine with Walschaert gear, 67 to 69

inclusive
Derivation of lead through the Walschaert combination lever,

157

Designing and erecting the Walschaert valve gear, 95-126
Designing the Walschaert gear, and explanation of diagrams,

104, 105
Details of the Walschaert link, 44 to 49 inclusive
Difference between Walschaert and Stephenson motions, 151, 152
Difference in set-up of Walschaert gear as between inside and

outside admission valves, 62 to 64 inclusive
Different methods of erection, 49 to 51 inclusive
Different styles of set-up of the gear, 19
Directness of Walschaert motion, 138, 139
Direct valve motion, 20
Disconnection of radius rod. Method of doing it, 176, 177
Disconnection of Walschaert and Stephenson gears, 170, 171
Does lost motion in the driving-boxes induce greater error in the
Walschaert gear than in the Stephenson motion? Does the
vertical motion of the engine affect the steam distribution

in the Stephenson gear? 164
Does the radius rod give motion to the valve, with reverse lever

on the centre? 160, 161
Does the rise and fall of the engine on springs affect the valve's

action with Walschaert gear? Position of valve with crosshead
in the centre of guides and reverse lever in centre notch of
quadrant, 165

E
ECCENTRIC rod broken. How to proceed, 179
Eccentric-rod connections, 43
Eccentric rod, testing for length of, 192 to 194 inclusive
Effect of broken side rod on engine with Walschaert gear, 174
Effects from lead, 154
Effect of valve advance to secure lead, 25
Engine standing as last mentioned, if valve is not exactly cen-

tred, the cause and remedy, 166
Enumerating the chief advantages of Walschaert gear, 129 to

131 inclusive
Equalized cut-off, Walschaert vs. Stephenson gear, 161, 162
Erected gear, inspection of, 101
Erecting and designing the Walschaert valve gear, 95-126