Rough and Tumble Engineering

by James H. Maggard

PART SECOND ________

WATER SUPPLY

If you want to be a successful engineer it is necessary to know all about the pump. I have no doubt that many who read this book, cannot tell why the old wooden pump (from which he has pumped water ever since he was tall enough to reach the handle) will pump water simply because he works the handle up and down. If you don't know this I have quite a 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 cock between the two horizontal check valves. The globe valve must be open so as to let the water in. A check valve, whether it is vertical or horizontal, will allow water to pass through it one way only, if it is in good working order. If the water will pass through both ways, it is of no account. Now, the engine starts on the outward stroke and draws the-plunger out of the chamber. This leaves a space in the barrel which must be filled. Air cannot get into it, because the pump is in perfect order, neither can the air get to it through the hose, as it is in the water, so that the pressure on the outside of the water causes it to flow up through the pipes through the first check valve and into the pump barrel, and fills the space, and if the engine has a I2-inch stroke, and the plunger is I inch in diameter, we have a column of water in the pump I2 inches long and I inch in diameter.

The engine has now reached its outward stroke and starts back. The plunger comes back with it and takes the space occupied by the water, which must get out of the way for the plunger. The water came up through the first check valve, but it can't get back that way as we have stated. There is another check valve just ahead, and as the plunger travels back it drives the water through this second check. When the plunger reaches the end of the backward stroke, it has driven the water all out. It then starts forward again, but the water which has been driven through the second check cannot get back and this space must again be filled from supply, and the plunger continues to force more water through the second check, taking four or five strokes of the plunger to fill the pipes between the second check valve and the hot water check valve. If the gauge shows I00 pounds of steam, the hot water check is held shut by I00 pounds pressure, and when the space between the check valves is filled with water, the next stroke of the plunger will force the water through the hot water check valve, which is held shut by the I00 pounds steam pressure so that the pump must force the water against this hot water check valve with a power greater than I00 pounds pressure. If the pump is in good condition, the plunger does its work and the water is forced through into the boiler.

A clear sharp click of the valves at each stroke of the plunger is certain evidence that the pump is working well.

The small drain cock between the horizontal checks is placed there to assist in starting the pump, to tell when the pump is working and to drain the water off to prevent freezing. When the pump is started to work and this drain cock is opened, and the hot water in the pipes drained off, the globe valve is then opened, and after a few strokes of the plunger, the water will begin to flow out through the drain cock, which is then closed, and you may be reasonably certain that the pump is working all right. If at any time you are in doubt as to whether the pump is forcing the water through the pipes, you can easily ascertain by opening this drain cock. It will always discharge cold water when the pump is working. Another way to tell if the pump is working, is by placing your hand on the first two check valves. If they are cold, the pump is working all right, but if they are warm, the cold water is not being forced through them.

A stop cock should be used next to boiler, as you ascertain whether it is open or shut by merely looking at it, while the globe valve can be closed by some meddlesome party and you would not discover it, and would burst some part of your pump by forcing water against it.

PART THIRD _________

It is very important when the pump fails to work to ascertain what the trouble is. If it should stop suddenly, examine the tank and ascertain if you have any water. If you have sufficient water, it may be that there is air in the pump chamber, and the only way that it can get in is through the stuffing box around the plunger, if the pipes are all tight. Give this stuffing nut a turn, and if the pump starts off all right, you have found the trouble, and it would be well to re-pack the pump the first chance you get.

If the trouble is not in the stuffing box, go to the tank and see if there is anything over the screen or strainer at the end of the hose. If there is not, take hold of the hose and you can tell if there is any suction. Then ascertain if the water flows in and then out of the hose again. You can tell this by holding your hand loosely over the end of the hose. If you find that it draws the water in and then forces it out again, the trouble is with the first check valve. There is something under it which prevents its shutting down. If, however, you find that there is no suction at the end of hose examine the second check. If there should be something under it, it would prevent the pump working, because the pump forces the water through it; and, as the plunger starts back, if the check fails to hold, the water flows back and fills the pump barrel again and there would be no suction.

The trouble may, however, be in the hot water check, and it can always be told whether it is in the second check or hot water check by opening the little drain cock. If the water which goes out through it is cold, the trouble is in the second check; but, if hot water and steam are blown out through this little drain cock, the trouble is in the hot water check, or the one next to the boiler. This check must never be tampered with without first turning the stop cock between this check and the boiler. The valve can then be taken out and the obstruction removed. Be very careful never to take out the hot water check without closing the stop cock, for if you do you will get badly scalded; and never start the pump without opening this valve, for if you do, it will burst the pump.

The obstruction under the valves is sometimes hard to find. A young man in southern Iowa got badly fooled by a little pebble about the size of a pea, which got into the pipe, and when he started his pump the pebble would be forced up under the check and let the water back. When he took the check out the pebble was not there, for it had dropped back into the pipe. You will see that it is necessary to make a careful examinations and not get mad, pick up a wrench and whack away at the check valve, bruising it so that it will not work. Remember that it would work if it could, and make up your mind to find out why, it don't work. A few years ago I was called several miles to see an engine on which the pump would not work. The engine had been idle for two days and the engineer had been trying all that time to make the pump work. I took the cap off of the horizontal check, just forward of the pump barrel, and took the valve out and discovered that the check was reversed. I told the engineer that if he would put the check in so that the water could get through, he would have no more trouble. This fellow had lost his head. He was completely rattled. He insisted that "the valve had always been on that way," although the engine had been run two years.

Now the facts in this case were as follows: The old check valve in place of the one referred to had been one known as a stem valve, or floating valve. This stem by some means, had broken off but it did not prevent the valve from working. The stem, however, worked forward till it reached the hot water check, and lodged under the valve, which prevented this check from working and his pump refused to work, the engineer soon found where the stem had broken off, and instead of looking for the stem, sent to town for a new check, after putting this on the pump now refused to work for two reasons. One was, he had not removed the broken stem from the hot water check, and another was, that the new check was in wrong end to. After wasting another hour or two he finally found and-removed the stem from the hot water check, but his pump still refused to work. And then as the boys say, "he laid down," and when I called his attention to the new valve being in wrong, he was so completely rattled that he made use of the above expression.

There are other causes that would prevent the pump working besides lack of packing and obstructions under the valves. The valve may stick. When it is raised to allow the water to flow through, it may stick in the valve chamber and refuse to settle back in the seat. This may be caused by a little rough place in the chamber, or a little projection on the valve, and can generally be remedied by tapping the under side of check with a wrench or hammer. Do not strike it so hard as to bruise the check, but simply tap it. If this don't remedy the trouble, take the valve out, bore a hole in a board about I/2 inch deep and large enough to permit the valve to be turned. Drop a little emery dust in this hole. If you haven't any emery dust, scrape some grit from a common whetstone. If you have no whetstone, put some fine sand or gritty soil in the hole, put the valve on top of it, put your brace on the valve and turn it vigorously for a few minutes, and you will remove all roughness.

Constant use may sometimes make a burr on the valve which will cause it to stick. Put it through the above course and it will be as good as new. If this little process was generally known, a great deal of trouble and annoyance could be avoided.

It will not be necessary to describe other styles of pumps. If you know how to run the cross head pump, you can run any of the others. Some engines have cross head pump only. Others have an independent pump. Others have an injector, or inspirator, and some have both cross head pump and injector. I think a farm engine should be supplied with both.

It is neither wise nor necessary to go into a detailed description of an injector. The young reader will be likely to become convinced if an injector works for five minutes, it will continue to work, if the conditions remain the same. If the water in the tank does not become heated, and no foreign substance is permitted to enter the injector, there is nothing to prevent its working properly as long as the conditions are within the range of a good injector. It is a fact that with all injectors as the vertical distance the injector lifts is increased, it requires a greater steam pressure to start the injector, and the highest steam pressure at which the injector will work is greatly decreased. If the feed water is heated, a greater steam pressure is required to start the injector and it will not work with as high steam pressure. The capacity of an injector is always decreased as the lift is increased, or the feed water heated. To obtain the most economical results the proper sized injector must be used. When the exact quantity of water consumed per hour is known it can be easily determined from the capacities given in the price lists which sized injector must be selected.

An injector must always be selected having a maximum capacity in excess of the water consumed. If the exact amount of water consumed per hour is not known, and cannot be easily determined, the proper size can be approximately determined from the nominal H. P. of the boiler. The usual custom has been to allow 7 I/2 gallons of water per hour, which is a safe rule for the ordinary type of boiler.

WHAT A GOOD INJECTOR OUGHT TO DO.

With cold feed water, a good injector with a two foot lift ought to start with 25 pounds pressure and work up to I50 pounds. With 8 foot lift, ought to start at 30 pounds and work up to I30. With feed water heated to I00 degrees Fahrenheit it should start with the same lift, that is, will say 2 foot, at 26 and work Up to I20, and at 8, from 33 up to I00. You will see by this that conditions, consisting of variation of temperature in the feed water and different lifts, change the efficiency of your injector very materially, and the water can soon get beyond the ability of your injector to work at all. The above refers more particularly to the single tube injector. The double tube injector under the same conditions as above should work from I4 pounds to 250, and from I5 to 2I0, but as this injector is not generally used on farm engines you will most likely not meet with it very often.

The injector should not be placed too near the boiler, as the heat from it will make it difficult to start the injector each time after it has been standing idle.

If the injector is so hot that it will not lift the cold water, there is no way of cooling it except by applying the water on the outside. This is most effectively done by covering the injector with a cloth and pouring water over the cloth. If, after the injector has become cool, it still refuses to work, you may be sure that there is some obstruction in it that must be removed. This can be done by taking off the cap, or plug-nut, and running a fine wire through the cone valve or cylinder valve. The automatic injector requires only the manipulation of the steam valve to start it. There are other makes that require, first: that the injector be given steam and then the water. To start an injector requires some little tact, (and you will discover that tact is the handiest tools you can have to make you a good engineer). To start an injector of the Pemberthy type; first give it sufficient steam to lift the water, allowing the water to escape at overflow for a moment or long enough to cool the injector, then with a quick turn shut off and open up the supply which requires merely a twist of the wrist.

If the injector fails to take hold at once don't get ruffled but repeat the above move a few times and you will soon start it, and if you have tact, (it is only another word for natural ability) you will need no further instructions to start your injector. But remember that no injector can work coal cinders or chaf and that all joints must be air tight. Don't forget this.

It is now time to give some attention to the heater. While the heater is no part of the pump, it is connected with it and does its work between the two horizontal check valves. Its purpose is to heat the water before it passes into the boiler. The water on its way from the pump to the boiler is forced through a coil of pipes around which the exhaust steam passes on its way from the cylinder to the exhaust nozzle in the smokestack.

The heaters are made in several different designs, but it is not necessary to describe all of them, as they require little attention and they all answer the same purpose. The most of them are made by the use of a hollow bedplate with steam fitted heads or plates. The water pipe passes through the plate at the end of the heater into the hollow chamber, and a coil of pipes is formed, and the pipe then passes back through the head or plate to the hot water check valve and into the boiler.

The steam enters the cylinder from the boiler, varying in degrees of heat from 300 to 500. After acting on the piston head, it is exhausted directly into the chamber or hollow bed-plate through which the pipes pass. The water, when it enters the heater, is as cold as when it left the tank, but the steam which surrounds the pipes has lost but little of its heat, and by the time the water passes through the coil of pipes it is heated to nearly boiling point and can be introduced into the boiler with little tendency to reduce the steam. This use of the exhaust steam is economical, as it saves fuel, and it would be injurious to pump cold water directly into a hot boiler.

If your engine is fitted with both cross head pump and injector, you use the injector for pumping water when the engine is not running. The injector heats the water almost as hot as the heater. If your engine is running and doing no work, use your injector and stop the pump, for, while the engine is running light, the small amount of exhaust steam is not sufficient to heat the water and the pressure will be reduced rapidly. You will understand, therefore, that the injector is intended principally for an emergency rather than for general use. It should always be kept in order, for, should the pump refuse to work, you have only to start your injector and use it until such time as you can remedy the trouble.

We have now explained how you get your water supply. You understand that you must have water first and then fire. Be sure that you have the water supply first.

THE BLOWER

The blower is an appliance for creating artificial draught and consists of a small pipe leading from some point above the water line into the smoke stack, directly over the tubes, and should extend to the center of stack and terminate with a nozzle pointing directly to top and center of stack; this pipe is fitted with a globe valve. When it is required to rush your fire, you can do so by opening this globe and allowing the steam to escape into the stack. The force of the steam tends to drive the air out of the stack and the smoke box, this creates a strong draught. But you say, "What if I have no steam?" Well, then don't blow, and be patient till you have enough to create a draught; and it has been my experience that there is nothing gained by putting on the blower before having fifteen pounds of steam, as less pressure than this will create but little draught and the steam will escape about as fast as it is being generated. Be patient and don't be everlastingly punching at the fire. Get your fuel in good shape in fire box and shut the door and go about your business and let the fire burn.

Must the blower be used while working the engine. No. The exhaust steam which escapes into the stack, does exactly what we stated the blower does, and if it is necessary to use the blower in order to keep up steam, you can conclude that your engine is in bad shape, and yet there are times when the blower is necessary, even when your engine is in the best of condition. For instance, when you have poor fuel and are working your engine very light, the exhaust steam may not be sufficient to create enough draught for poor coal, or wet or green wood. But if you are working your engine hard the blower should never be used; if you have bad fuel and it is necessary to stop your engine you will find it very convenient to put on the blower slightly, in order to hold your steam and keep the fire lively until you start again.

It will be a good plan for you to take a look at the nozzle on blower now and then, to see that it does not become limed up and to see that it is not turned to the side so that it directs the steam to the side of stack. Should it do this, you will be using the steam and getting but little, if any, benefit. It will also be well for you to remember that you can create too much draught as well as too little; too much draught will consume your fuel and produce but little steam.