The traction engine catechism ; a hand book of practical information for the farm engineer and thresherman, compiled from regular issues of the Threshermen's review, with additions of reference tables ...

Preface

Several years ago The Threshermen's Review established a department of questions and answers; a department devoted to the printing of plain questions from threshermen, relating to the business of traction engine operation, and of threshing.

This met with immediate and unqualified favor among threshermen, and every issue of The Threshermen's Review since has contained a goodly number of bona fide questions from threshermen and our answers thereto.

Then came numerous suggestions that these questions and answers be assembled in book form for convenient reference; and these suggestions finally resolved themselves into so insistent a demand that the thing be done that we decided to comply with it. Hence this book.

This work makes no pretentions of completeness; of covering all the questions that may arise in traction engine practice. It is just a compendium of the matter printed in our department devoted to questions and answers since its establishment. It therefore has no "plot"; no attempt has been made to make of it a complete handbook of the traction engine. It is simply what its title indicates: a catechism of the traction engine, with this difference from other works of the kind, that the questions dealt with are those that have actually been asked by working threshermen who have met the problems indicated and have brought them to this paper for solution.

In conclusion, we wish to thank our readers for their many expressions of appreciation of this department; and we hope that this condensation of it will be of some service to them in solving many of the problems that confront them in the operation of their machinery.

The Threshermen's Review.

Chapter I. The Engine

Definition of Engine — Limit of Piston Speed — Percentage of Heat of Coal in Steam — The Double Engine — Explanation of Indicator Card — Point of Cut-off — Fitting new Engine Bed — Increased Fuel Consumption — Difference in Economy — Loss of Power — The Compound Engine — Boiler Pressures — Crosshead Adjustment — Testing Fit of Piston — Broken Wrist Pin — Replacing Piston Rings — Back Pressure — Removing Back Pressure — Removing Crank Disc — Size of Steam Pipe 1 1

Chapter II. The Boiler

Grate Surface — Blowing Out — Pressures — Foaming — Fuel Consumption — Tensile Strength Test — Jacketing the Boiler — Potatoes as Scale Removers — Leaky Stay Bolts — Repairing Tubes — Patching the Crown Sheet — Causes of Explosions — Bagged Plates* — Hydrostatic — Cold Water — Tests — The Safety Plug — Bulge in Crown Sheet — Copper Ferules — Repairing Flue Sheet — Removing Stay Bolts — Loose Boiler Brackets — Leak at Fire Door 46

Chapter III. The Valve Gear

Balanced and Unbalanced Valves — The Corliss Valve — Setting the Valve — The Woolff Valve Gear — Various Matters Explained — The Link Motion — Slipped Eccentric — The Russell or Giddings Valve — Setting Valve on Peerless Engine — Setting Marsh Reverse — Truing the Valve and Seat — Running when Reverse is on Center — Setting Valve on Star Engine 82

Chapter IV. Horse Power

Standard, How Established — Mean Effective Pressure — Figuring Horse Power — The Prony Brake — Horse Power Compared with Engine Power in Plowing — Result of Changing Pinion on Crank Shaft — Catalogue Ratings — Effect of Flywheel — Boiler Horse Power 109

Chapter V. Boiler Feeding

Injector Troubles — The Heater — Continuous Feeding — Pump Questions — Failure of Crosshead Pump — Using Jet on Level 124

Chapter VI. Lubrication

Single and Double Connection Lubricators —

Amount of Oil Needed — Oil Pump Troubles — Graphite in the Lubricator — Graphite as a Lubricant — Long Feed Pipe for Cylinder Oil — Effects of Scant Lubrication — Attaching Lubricator to Simple Double Engine — Discoloration of Oil in Sight Feed Glass — Breaking of Sight Feed Glass 134

Chapter VII. Firing

Thickness of Fire — Banking the Fire — Clinkers — Rocking Grates — Effect of the Exhaust Nozzle — Firing with Straw — The Straw Stoker — The Spark Arrester — A Poor Steamer — Burning Slack Coal — Blower not Harmful to Flues 145

Chapter VIII. The Governor

Uncertain Control — Changing Speed — On the Compound Engine — The Horizontal Governor — The Eclipse Governor 154

Chapter IX. Bearings

Babbitt for the Connecting Rod — Rebabbitting Main Shaft — Lining Brass Boxes with Babbitt — Pound — Babbitting Crank Pin Brasses — The Crosshead — Pressure on Bearings — Lining Up the Crosshead 159

Chapter X. Miscellaneous

Laying Up the Engine — Straightening Spokes

— Loose Flywheel — Best Place for Driving Axles — "Dope" for Screw Joints in Pipe- Malleable Castings — Melting Temperatures — Soldering Flux — Comparative Fuel Values — Weight of Air and of Steam — Steam Chest Pressure — Taper Waist Boilers — Splicing Gandy Belt — Removing Flywheel — Changing Brass Lining in Steam Pump Cylinder — Relative Value of High and Low Drivers — Soot as Paint — A Frozen Steam Gauge — Mending Broken Spokes in Flywheel — Comparative Weights of Steam and Water — Grinding Globe Valves — Heating of Cylinder Boxes — Finding Dead Center 169

Appendix

When Safety Appliances Are Unreliable — Steam Engine Indicator — Keys and Set Screws on Farm Machinery — Compensating Gear — Engine Horse Power — Shafting — Belting — Table of Belt Horse Power — Table of Belt Contacts — Speed of Pulleys — Size of Pulleys — Table of Diameters, Areas and Circumferences of Circles — Table of Properties of Saturated Steam 201

Tradion Engine Catechism.

Chapter I. The Engine

Q. — What is an engine?

A. — The word engine is used sometimes to indicate contrivances that our correspondent would probably not recognize as coming under this classification. For instance, a large gun might be termed an engine of destruction; a torpedo boat or even a battleship might also be so designated. The Standard Dictionary is authority for the foregoing; also that any agency or instrumentality devised or designedly employed may be so termed. As "An engine of oppression. " In mechanics, an engine is a machine for converting some motive energy, usually heat, into work. This is an engine as generally meant; but the term is also applied to elaborate and complex machines for doing intricate and superior work.

ii

Q. — What is the limit of piston speed to which a traction engine should be run ?

A. — The rotative speed of a traction engine will keep it below the limit. A 1 2-inch stroke engine running 300 revolutions per minute has a piston speed of 600 feet per minute. Locomotives run as high as 1,000 feet, and engines in torpedo boats as high as 1,200 feet per minute.

Q. — How much of the heat of coal is gotten into the steam?

A. — Authorities on the subject tell us that about 77 % of the heat of coal is given to the steam.

Q. — I bought a double cylinder simple engine this fall. I understood when I bought it that it had no dead center. I find that it has places where it will not start with the throttle wide open and no load. The agent who sold me the engine tells me I have to throw the reverse lever down toward the end of the quadrant to start it. Now, the engine will run hooked up in the notches toward the center of the quadrant, and sometimes it will start there. Why does it not start there every time? Surely there must be something wrong with the engine or it must have a dead center, although the catalogue claims the engine has no dead center.

A. — It is true that a double engine with its cranks set at 90 has no dead center, as only one crank can be on the dead point at a time. While one crank is on the center the other is in position to do business if steam is turned into the cylinder, but if the reverse

THE TRACTION ENGINE CATECHISM.

lever is in the center notch it cannot start, and even if the reverse lever is thrown far enough ahead so that the valve cuts off the steam at one-half stroke, the engine cannot move when the cranks are set as mentioned in the foregoing. However, the engine will start with the valve gear set at one-half cut-off, providing the one crank is set, say at one-eighth or one-fourth stroke to begin with.

The correct way to start a double engine is to always have the reverse lever thrown well down to the end of the quadrant, and when the engine is started hook it up to the point at which you wish it to run. This is the way locomotives are started, and a double traction engine is built on the same general lines.

Q. — Enclosed find a card taken from my engine. Please tell me what is wrong with it, or what is wrong with my engine. I set the valve with the same lead on each end, but the diagram on the card shows that one end is different from the other. Please tell me why this is. The engine has a link reverse and seems to be in good condition.

A. — We have made a cut of the diagram, shown in Fig. 1. The cause for one end being larger than the other is that the cut-off is not equal. It happens with a valve gear of this nature that when the lead is equal the cut-off is unequal. To get the cut-off equal the lead must needs be unequal. An unequal lead will be more desirable than will be the unequal cut-off, for it happens that the piston is practically standing still when the valve is opening the port, so it cannot effect the engine as much as the unequal cut-off as shown in Fig i. Shift your valve so that it will make a card which will be equal on each end. Then if you will send it to us we will make a cut from it and publish it.

The reason why an engine with an ordinary valve gear cannot have an equal lead and an equal cut-off is due to a peculiarity in the travel of the connecting rod; writers on this subject call it "The angularity of the connecting rod" — in consequence of which the piston travels faster at one end of the cylinder than at the other. Fig. 2 shows the unequal positions of the crank pin, a, b, c, d and e, while the positions of the crosshead pin are equal; a/ b,' c,' d' and e! In Fig. 3 the positions of the crank pin are equal, while the positions of the crosshead pin are unequal. In Fig. 2 the crosshead ,(/, is on the center line while the position of the crank pin, c, is off the center line. One

THE TRACTION ENGINE CATECHISM.

can readily see that the distance from a to c is greater than from c to e y while from a to d is the same as from c to e . Since the eccentric is carried on the shaft and since the motion of the shaft is uniform, d'e'

due to the balance wheel and since it takes as much time for the crank pin to travel from a to c and from c to e in Fig. 3, the piston will travel slower from a' to c than from c to e . This accounts for the unevenness of the card when the valve is set with equal lead.

This can be corrected in an engine with a rocker arm instead of a valve rod guide when the rocker arm is set to move farther on one side of the center than the other. This is done in locomotive practice.

Q. — Would it be advisable or good to change the position of the piston in an engine after the engine had been run for four years; the piston and rings being run in the same position all that time?

2. — How can a click be stopped in the cylinder, caused, I think, by wear of the piston rings?

A. — If a piston is properly made the rings will travel over the counter bore of the cylinder. If they do not they will wear a shoulder in the cylinder. In this case the piston will have to be taken out and the shoulder filed off before it is safe to change the position of the piston.

2. — If the rings are loose in the piston, which they likely are if they click, the only remedy is to get new rings w T hich are wider and fill up the grooves.

Q. — Will some one tell me why an engine should not be reversed without shutting off steam ? One expert machine agent called me down for doing it, and said it injured the valve to slide it with the lever w T hen under pressure. I presume I am dense, but I can't see what difference it makes to the valve, to draw it with lever or eccentric. I know it gives the gearing a bad jar to throw the reverse quickly and I would like to know any other reasons. My engine is an old Pitts, used eighteen falls. Has a screw throttle that is slow to use, consequently it is always handled with the reverse lever. The valve has not been repaired and have put in no new rings nor no new gears. It works good and steams easily.

A. — If an engine is well designed, reversing it without shutting off the steam will not hurt it in any respect. In fact, there is more harm to come from reversing with the throttle closed when engine is running at a high speed, for when an engine is running in an opposite direction to which the valve gear is set the engine is turned into a pump and it pumps air from the stack through the exhaust nozzle into the boiler. This can be done on a locomotive coasting down hill. However, there are release valves on the steam ports which prevent this on a locomotive; but on a traction engine it can only be done when the engine is pulled by another engine or by running the engine to a very high speed and then suddenly reversing it. If the flywheel is very heavy it is more effective than if it is light. This we have said will pump air into the boiler; but if the engine is suddenly reversed while the engine is at a high speed and while the throttle is shut, the air cannot go into the boiler, but is pumped into the steam pipe against the throttle, and if enough power is put to the flywheel of the engine something will burst; but if the throttle is left open the piston never has any more pressure than is in the boiler to pump against and that should not hurt it.

Q. — Which will use more fuel and water, a 12 h. p. engine running at 225 revolutions per minute, or the same engine at 250, the load remaining the same?

A. — This depends on the load. If the engine is overloaded the higher speed is the better, but if the load is too small for the engine the slow r er speed will be the better.

Q. — I have a Russell 14 h. p. compound engine and when I pull the reverse lever open it pounds hard, and when I put it near center notch it does not pound so badly but will not furnish power enough. I admit steam in the low pressure cylinder early and that helps, but causes back pressure. What would you advise to do to help the case ?

A. — From your description we are inclined to believe that your engine is too small for the work you are doing. An engine with an expansion gear, as the Russell, should not be worked with the reverse lever down in the end notch, as this notch is only for convenience in starting or pulling through a hard place when occasion demands. In this notch the valve cuts off the steam at about three-fourths of the stroke and at this point the compression is low and does not afford sufficient cushion for constant use. The engine should be large enough for the work, so that it can be hooked up to say one-half stroke. This would be late enough for a compound engine. A simple engine should be hooked up to one-third or one-fourth cut-off. If you are not ready to purchase a new engine, the best remedy w T e can offer you is to carry as high pressure as your boiler will safely permit and hook your valve gear up as far as possible, that is to run the engine with the reverse lever as close to the center of the quadrant as possible.

Q. — Which is the most economical point of cut-off at which to run an engine? I notice that some engines have no means of hooking up the valve gear. I presume they are set at the most economical point, and would like to know where that point is, as my engine has a great range of adjustment on the reverse quadrant. Can an engine be hooked up too far for economy, and if so, what is the limit?

A. — An automatic single valve engine is generally supposed to be cut-off at one-fourth of the stroke. It would hardly be practical to try to run a traction throttling engine at that cut-off, as the load is so irregular that the cut-off has to be set late enough to take care of the maximum load. The traction engines with a fixed cut-off are set to cut off at about one-half stroke. The best place to run the valve gear on a traction engine is to hook it up as far as possible. The engines are very seldom large enough for the work to get the best economy, so there is no danger of hooking them up too far. The best way to find the place for the reverse lever is, after the engine is at work to hook it up until the speed slacks a little, then move it one notch forward. This is generally enough to take care of the maximum loads. However, it should never be hooked up closer than to one-fourth cut-off.

Q. — In putting on a new engine bed on an engine would you make rigid fastening on pillow blocks when the boiler is cold or would you steam up to about 75 lbs. — working pressure 150 lbs. — to divide the strain on the engine bed equally between expansion and contraction of the boiler, which apparently cracked the lower side of guide of old bed?

2. — The new bed comes with bearing for main shaft babbitted. Opposite bearing has never been opened and seems to be in good order. Would you put it up without rebabbitting both new and old bearings?

3. — What h. p. will a 6^ x 10, 10-inch stroke tandem compound engine develop, running 230 revolutions per minute, at 150 lbs. pressure?

A. — On some engines there is a slip joint where the cylinder is bolted to the boiler which allows the boiler to expand and contract without exerting an undue strain on the castings; but if the cylinder and bed or frame are bolted rigidly to the boiler it certainly would help matters to bolt it up at a medium temperature of the boiler and thus reduce the danger of breaking the frame.

The temperature of the boiler at 150 lbs. gauge pressure is about 355° F. Say the average temperature of the atmosphere is 45 °, this would make the average temperature of the boiler 200 . Steam at atmospheric pressure, or just before it shows on the steam gauge, is 212 ; so you see a medium temperature would be at about this point. As there are only about 50 between 75 and i5olbs. pressure, 75 lbs. would be a medium pressure but would not be a medium temperature.

2. — The main box in the engine frame is square with the cylinder and in the factory the shaft is bolted fast by means of the main bearing cap, so that after the cylinder and frame are bolted to the boiler the shaft is rigidly held in place and the outer bearing is babbitted last. It may be possible that the outer bearing will be exactly in position. This can be found out by close examination, and if it is not exactly in position the babbitt should be cut out and replaced after the cylinder and frame are bolted to the boiler, and shaft is securely held by the cap. To insure the shaft being held properly, the liners should be taken out from between the cap and box.

3. — The nominal h. p. as given by the manufacturers is 20 and the maximum brake h. p. is 49.

Q. — Do you think that the oil that runs down over the side of boiler will do any harm if not removed?

2. — We do not use our governor when sawing and I notice that the engine will run faster when hooked up than it will when the reverse is in the last notch. This is when engine is not working any and just enough steam admited to run, say, 125 revolutions. (Woolff reverse) . Can you tell me why this is?

A. — The only harm the oil on the boiler does is to its looks.

2.— Your engine running without the governor controlling it and using the throttle to control the engine will run faster cutting off early than late, for the reason that the steam w T orks on expansion to a higher degree when cutting off early, and thus getting more value out of the steam. This is a proof that u hooking up" helps the economy. On a cross compound engine, when it is arranged so that it can be run either simple or compound, and when a certain amount of steam is admitted by the throttle in both cases, the engine will run faster running compound than it will running simple with the same amount of steam. This is a proof that a compound engine is more economical than a simple engine as it shows that there is more value gotten out of the steam in running compound.

Q. — Does hammering on a check valve or an injector do any good in starting it when it is slow in taking water?

A. — Hammering on an injector will do no good in helping the injector to take the water. It sometimes happens that when an automatic injector runs at the overflow a little tap will do some good. Hammering on a check valve can do no good in starting an injector.

Q. — My engine is a 22 h. p. and my separator is a 40 x 62 with a blower of a standard kind, feeder and weigher. Now in dry grain the engine handles it with perfect ease and yet uses up from seven to eight tw r elve-barrel tanks in a day of about 12 hours. There is no leak of water and hardly any of steam except the regular use. The valve is set perfect. I took the cylinder head off to see if the rings leaked, but they leaked just a little on one side of the piston head, but it was so little I don't think it would hurt that much. The valve don't leak either as far as I could judge. Last year we used only three to four and a half tanks a day and the grain was all wet and tough, so the engine had to work harder. This year it was easier, yet she uses more water.

A. — If the piston and valve are reasonably tight and the valve is set correctly, the trouble is evidently in the running of the engine. Perhaps you hooked up the valve gear last year and this year you run the valve at full stroke. This would make some difference in the water consumption. If your boiler foams this also would cause it to take more water. It may be to your advantage to have a good machinist look over your engine, if possible a representative of the factory at which it was built. It may be that there is something out of place which you do not notice. There is something radically wrong when an engine takes twice as much water as it did a year ago.

Q. — What is the difference in the economy of different classes of engine? Why would it not pay to have a higher grade engine for the traction engine, say a Corliss and condensing engine?

A. — The additional first cost of the engine is one thing in the way, although there is room for some advancement along this line. An automatic cut-off engine for the thresherman may not be far off; but as for a Corliss and condensing engine for traction work, this may never come, especially the latter. The water consumption of a single valve simple, non-condensing engine is from 30 to 33lbs. per hour per h. p. ; a compound single valve non-condensing engine is from 22 to 25lbs. ; a compound single valve condensing from 14 to 16 lbs.; a simple Corliss non-condensing engine, from 27 to 30 lbs.; a compound Corliss condensing engine, from 12 to 15 lbs.; a triple expansion Corliss condensing engine from 10 to 14 lbs.; steam turbine, high grade, 15 lbs.

Q. — I have a complete outfit consisting of a 25 h. p. engine, 42 x 66 separator, w T ith self feeder, blower and weigher. I would like the opinion of The Review in regard to the engine. It has a cylinder 10 inches in diameter and 12-inch stroke, with a Woolff reverse gear. It don't seem to have as much power as it should and pounds terribly when doing hard work, especially when the relief exhaust is closed. When the reverse lever is in the last notch the valve only opens the ports about three-fourths of their width, and cuts off at about two-thirds stroke, while the lead is nearly one-eighth inch.

Don't you think there is too much back pressure due to compression and lead, which also pushes the valve off its seat and lets it come back with a pound?

Would not a new eccentric strap that has the connection for the eccentric rod farther up towards the block give the valve more throw and less lead?

A. — A valve need not open its port full to admit steam, as the port is made wide enough to let the exhaust escape at a low pressure, say, almost atmospheric pressure, and at this pressure the volume is much greater than at boiler pressure. In the ordinary size traction engine one-fourth of an inch opening for the live steam into the cylinder will be as efficient as three-fourths opening to let the exhaust steam out of the cylinder. On investigation you will find that when the valve gear is hooked up so that there is but a small port opening to admit live steam, the port is always opened wide for the exhaust steam. One-eighth of an inch is not far from the right amount of lead for this size engine. One-thirty-second of an inch less might be better, but in later years engines have been given more lead than before the engine indicator was in use by traction engine builders. It will be interesting to you to find out how much the piston travels while the lead is effected, in other words move the engine in the direction in which it runs until the valve is just ready to open, make a mark on the crosshead shoe and guide, then move the engine to the end of its travel and you will be surprised to see how little the piston moves to accomplish the lead. In this position of the engine's travel, the valve is moving its fastest and the piston is moving its slowest, and this is why a little excessive lead is not as detrimental as one would suppose at first glance. At all events we do not think it would pay you to get a new eccentric strap to reduce the lead.

Your engine does not pound from excessive compression. A lack of compression would be more apt to cause a pound. When the valve gear is hooked up to effect an early cut-off, the compression is higher and you will find this is where the engine runs the smoothest. Your best plan would be to hook the valve gear up as far as possible, to not only get a quiet, but also an economical engine. Any looseness about the boxes always makes more noise when the engine is cutting off late in the strokes.

Q. — In a crosshead pump, such as is used on most traction engines, where one valve works over the other, what is the best thing to use to reduce the lift of the valves and how to hold it in place?

2. — What is the proper lift of pump valves?

3. — How is the diameter of round valve seats measured; in the small opening at the bottom, or at the top?

4. — What is the best way to pack a piston rod and what is the best packing to use?

5. — What is the best packing for a crosshead pump?

6. — In an old engine on which the babbitting is worn down to the box so it heats, how can we continue to run it without stopping to rebabbitt? Can the boxes be bushed with anything outside of rebabbitting?