The Link Reverse Being Used.
First, see that all the lost motion in the connecting rod, pillow
block bearings and cross-head is taken up; then throw the reverse
lever in last notch in quadrant, which would allow the engine to run
“over”; then, remove the steam chest cover. Next, loosen eccentric
(the eccentric rod of which is in direct line with the valve rod),
turn the eccentric completely around, and watch the valve to see
whether it laps the steam ports exactly the same amount at both ends,
or travels an equal distance from its central position both ways. If
it does, the valve is in proper position upon the rod. If it does not
travel equally, the valve must be made to do so by adjusting it upon
the valve rod, which is done by lengthening or shortening the rod, by
use of jam-nuts, with which the rod is usually furnished. After this
is done accurately, place the engine upon its forward center. This
is done by turning the engine forward until the cross-head is about ½
inch from end of its stroke and mark the position of the cross-head
upon the guide; then, with the use of long tram or dividers, mark from
any convenient point on the frame to the band wheel or disc, and mark
both points with prick-punch. Again turn the engine forward until the
cross-head completes its stroke and comes back to the mark made on the
guide; then, with the same long tram or dividers, mark the band wheel
or disc as before from the prick mark already made on the frame.
Midway between punch marks on band wheel or disc, which can be found
by use of dividers, will give the point which will place the engine
on the “center” by turning engine back far enough to allow the long
tram or divider to fit in punch mark on frame, and center punch mark
on band wheel or disc. Now turn the eccentric over in the direction in
which the engine is to run, until the valve gives the proper amount
of lead on the front of steam port, which is about ¹/₃₂ of an inch,
and fasten eccentric with set-screw. Then turn engine over the way it
is to run, and place it upon its back center. This is done exactly
as before described for forward center, and if the valve is properly
proportioned, it will give the required ¹/₃₂ of an inch lead on the
back steam port, and valve will be properly set for running in this
direction.
Now throw the reverse lever in the last notch in opposite end of
quadrant, which would allow the engine to run “under”, then loosen the
other eccentric (the eccentric rod of which is in a direct line with
the valve rod), and proceed same as described when engine is running
“over”, to get valve to lap both steam ports equally. Then place engine
upon either center and move the eccentric in opposite direction from
the other eccentric until the valve gives the ¹/₃₂ of an inch lead to
steam port, fasten the eccentric and place the engine upon opposite
center, and the amount of lead should be the same on both steam ports,
and the valve properly set.
The valve being set, replace the steam chest cover, and secure the
eccentrics perfectly tight by screwing the set-screws up hard to
prevent them from slipping.
Always set the valve so as to run the engine backwards or “under”
first.