Rough and Tumble Engineering | Page 9

task on my hands, for you must not attempt to run an
engine until you know the principle of the pump. If you do understand
the old town pump, I will not have much trouble with you, for while
there is no old style wooden pump used on the engine, the same
principles are used in the cross head pump. Do not imagine that a cross
head pump means something to be dreaded. It is only a simple lift and
force pump, driven from the cross head. That is where it gets its name
and it don't mean that you are to get cross at it if it don't work, for nine
times out of ten the fault will be yours. Now I am well aware that all
engines do not have cross head pumps and with all respect to the
builders of engines who do not use them, I am inclined to think that all
standard farm engines ought to have a cross head pump, because it is
the most simple and is the most economical, and if properly constructed,
is the most reliable.
A cross head pump consists of a pump barrel, a plunger, one vertical
check valve and two horizontal check valves, a globe valve and one
stop cock, with more or less piping. We will now locate each of these
parts and will then note the part that each performs in the process of
feeding the boiler.
You will find all, or most pump barrels, located under the cylinder of

the engine. It is placed here for several reasons. It is out of the way. It is
a convenient place from which to connect it to the cross head by which
it is driven. On some engines it is located on the top or at the side of the
cylinder and will work equally well. The plunger is connected with the
cross head and in direct line with the pump barrel, and plays back and
forth in the barrel. The vertical check valve is placed between the pump
and the water supply. It is not absolutely necessary that the first check
be a vertical one, but a check of some kind must be so placed. As the
water is lifted up to the boiler it is more convenient to use a vertical
check at this point. Just ahead and a few inches from the pump barrel is
a horizontal check valve. Following the course of the water toward the
point where it enters the boiler, you will find another check valve. This
is called a "hot water check." just below this check, or between it and
where the water enters the boiler, you will find a stop cock or it may be
a globe valve. They both answer the same purpose. I will tell you
further on why a stop cock is preferable to a globe valve. While the
cross head pumps may differ as to location and arrangement, you will
find that they all require the parts described and that the checks are so
placed that they bear the same relation to each other. No fewer parts
can be used in a pump required to lift water and force it against steam
pressure. More check valves may be used, but it would not do to use
less. Each has its work to do, and the failure of one defeats all the
others. The pump barrel is a hollow cylinder, the chamber being large
enough to admit the plunger which varies in size from 5/8 of an inch to
I inch in diameter, depending upon the size of the boiler to be supplied.
The barrel is usually a few inches longer than the stroke of the engine,
and is provided at the cross head end with a stuffing box and nut. At the
discharge end it is tapped out to admit of piping to conduct water from
the pump. At the same end and at the extreme end of the travel of the
plunger it is tapped for a second pipe through which the water from the
supply reaches the pump barrel. The plunger is usually made of steel
and turned down to fit snug in the chamber, and is long enough to play
the full stroke of engine between the stuffing box and point of supply
and to connect with the driver on the cross head. Now, we will take it
for granted, that, to begin with, the pump is in good order, and we will
start it up stroke at a time and watch its work. Now, if everything be in
good order, we should have good water and a good hard rubber suction

hose attached to the supply pipe just under the globe valve. When we
start the pump we must open the little pet