SUGGESTIONS TO BEGINNERS
AN eccentric wears the most at the heel or opposite the throw.
The lead given a locomotive is never changed by wear of the eccentric.
It is the lost motion in the valve gear that destroys the lead.
The majority of engineers, and especially the young men, think
that engines should have lead, which is erroneous. All the lead
a locomotive has decreases its power. All locomotive valves should
be set line and line, as the engine will then both run and steam
better. Here is a pointer on setting up wedges. A wedge has about
a sixteenth of an inch taper to the inch in length, therefore,
if the wedge is down one inch you have one-sixteenth of an inch
pound and so on. Often the boxes are stuck, and the engine rides
rough on account of the wedges being set up too tight. Engines
should be placed just leaving the back center when setting up
wedges. Take a bar and set them up tight, and then pull them back
about one eighth, or three sixteenths of an inch and you will
not have any pound or stuck boxes and the engine will ride good
so far as the boxes can effect a locomotive. The driving boxes
being stuck is the cause of engine frames being broken in most
cases. Every shop should have one man to setup wedges, or the
foreman should instruct the roundhouse men just how he wants it
done, and the breaking of locomotive frames will be stopped.
How to tell when a locomotive is blind to such an extent that
it will not do the work required: place engine on dead centre
and put reverse-lever in full stroke, then pull up the lost motion,
as the steam will then open cylinder cocks, and give the engine
steam. If steam does not flow out of cocks, pull the lever back
until it does so, and you can tell accurately how much the engine
is blind. Mark the valve stem at gland before moving the lever,
and the space between the mark and gland, when the steam blows
out, represents the amount of the engine's blindness.
The way to get the proper length of reach-rod. Place the reverse-lever
in the centre of the quadrant, then plumb arm on tumbling shaft,
and the distance between the two points will give the proper length
to make the reach-rod on all locomotives.
When necessary to brass an engine truck on account of running
hot, run out your journal jack about three quarters of an inch
higher than the corner of the box, take out the cellar, place
jack on tie and corner of box, and move the engine until the jack
is perpendicular. You can then take the brass out and put in another
in less than five minutes.
If the valves in a locomotive have five inches' travel and
the eccentric has only four and a half inches' throw, where does
it get the other half inch? By making rocker arm shorter at the
link than the one that connects with the valve-rod.
Why does a locomotive slip when she is given steam? Because
the power is too great for the adhesion on the rail. Link the
engine back and you reduce the power and stop the slipping.
When a locomotive rocks too much while running, the male casting
on cylinder saddle is too small in diameter. It should be between
twenty and twenty-four inches in diameter with rigged truck centre
plate. If this fails to stop the rocking, there is not enough
counterbalance in the driving wheels. The lack of sufficient counterbalance
causes a locomotive to rock more and ride rougher than any other
one thing pertaining to a locomotive.
HOW TO SET AN ENGINE'S VALVES BY SOUND
Watch the cross-head and if the loud exhaust occurs when it
is passing the forward centre, lengthen the eccentric blade enough
to divide the travel of the valve.
If on back centre, shorten the eccentric blade. Forcing the
steam through a smaller opening is what makes the loud exhaust.
Table of Contents
| Next Chapter | Contents