head broken, what will control the compressor?

Answer. The maximum pressure top. Question. What would be the effect if the pipe leading to the maximum pressure top breaks, and what should be done?

Answer. Plug the pipe toward the main reservoir to prevent the waste of air. The excess pressure top will control the compressor in release, running and holding position of the brake valve, but will have no control in lap service or emergency positions; therfore, the action of the compressor would have to be governed by throttling the steam valve.

Answer. In service braking the brake cylinder pressure will be two and onehalf times the reduction of brake pipe pressure up to the point of equalization of the pressures in the pressure chamber and application chamber, unless the point of equalization be above the adjustment of the safety valve, which is 68 pounds. Putting it another way, if the pressure carried be 70 pounds, a 20-pound brake pipe reduction will cause the pressure chamber and application cylinder and chamber to equalize at 50 pounds, which means 50 pounds brake cylinder pressure will be obtained, while if 110 pounds pressure be used, equalization would take place at about 80 pounds, were it not for the safety valve, which holds the pressure at 68 pounds. In an emergency application, with 70 pounds brake pipe pressure, the application chamber being cut off, the pressure chamber pressure and application cylinder will equalize at 65 pounds. However, in emergency position of the automatic brake valve, the blow-down timing port is open, allowing air at main reservoir pressure to flow to the application cylinder, where the pressure is built up to the adjustment of the safety valve, or 68 pounds. When using 110 pounds brake pipe pressure, the pressure chamber and

application cylinder will equalize at 93 pounds, which will gradually be reduced to 72 pounds through a safety valve.

EFFECT OF OVERCHARGED BRAKE PIPE ON OPERATION OF AUXILIARY DEVICE GOVERNOR

Question. Our U. S. standard locomotives are equipped with power reverse gear, auxiliary device reservoir and governor. I have noticed that when the brake pipe becomes overcharged the fire doors won't operate, and in some cases the power reverse gear won't work. Where this condition exists there is no air at the fire door valve, but a couple of heavy reductions with the automatic brake valve will set everything all right. I do not understand why the overcharging of the brake pipe creates this condition, as the air used in the operation of the different devices is taken from the auxiliary device reservoir. An explanation of this will be greatly appreciated. E. I. P.

Answer. The trouble you refer to is due to the action of the auxiliary device governor. The purpose of this governor is to protect the supply of air for the air brakes from becoming depleted, due to the operation of the different air operated devices other than the brake. To accomplish this, all air operated devices, other than the brakes, are supplied with air from the auxiliary device reservoir, and the supply of air to this reservoir is controlled by the auxiliary device governor. The operation of this governor is much the same as the compressor governor, the only difference being the supply valve seats upward instead of downward as does the steam valve. The regulating spring above the diaphragm is generally adjusted at 15 pounds, and this, plus the feed valve pipe pressure, creates the total load above the diaphragm. When the main reservoir pressure, which is found under the diaphragm, slightly exceeds the pressure above, the diaphragm is forced upward, unseating the pin valve, allowing main reservoir air to flow to the top of the governor piston, forcing it downward, unseating the supply valve, allowing main reservoir air to flow to the auxiliary device reservoir.

Main reservoir air will continue to flow to the auxiliary device reservoir

until the pressure in the two reservoirs has equalized, or until the main reservoir pressure under the diaphragm becomes slightly. less than the combined spring and air pressure above, when the diaphragm will move downward, seating the pin valve, allowing the supply valve to seat, closing the connection between the two reservoirs. An example of this: Let us assume the feed valve adjusted at 70 pounds and the regulating spring in the auxiliary device governor at 15 pounds. If we now start the compressor having the automatic brake valve handle in running position, the pressure will build up in the main reservoir and brake pipe to the adjustment of the compressor governor and feed valve. As the pressure builds up in the feed valve pipe it also builds up in the chamber above the diaphragm of the auxiliary device governor; this would mean a total load of 85 pounds when the brake pipe pressure reached 70 pounds. Now when the main reservoir pressure becomes slightly greater than 85 pounds the diaphragm in the auxiliary device governor will be forced upward, unseating the pin valve, allowing air to flow to the top of the governor piston, unseating the supply valve, permitting main reservoir air to flow to the auxiliary device reservoir. Thus it will be seen that with a brake pipe pressure of 70 pounds, no air will go through the auxiliary device reservoir until the main reservoir pressure is greater than 85 pounds. However, if the feed valve fails to control the brake pipe pressurc at 70 pounds, that is, if the pressure becomes greater than this amount, it also means an increase of pressure above the diaphragm of the governor, which in turn means a delayed opening of the supply valve. Putting this another way, the supply valve in the auxiliary device governor will not open unless the main reservoir pressure is 15 pounds greater than the feed valve pipe pressure.

TEMPERATURE OF AIR LEAVING COM-
PRESSOR

Question. Will you please let me know through our JOURNAL, what is the temperature of the air as it leaves the compressor? L. M. N.

Answer. The temperature of the air as it leaves the compressor is dependent

on the rate at which it is compressed, the pressure to which it is compressed, the temperature of the air before compression, and the condition of the compressor, and as these conditions vary so will the temperature of the air delivered to the main reservoir. Air cannot be compressed without creating heat, as where the particles of air are crowded closer together, the friction of one particle moving over another is responsible for the heat created. Therefore the same amount of heat is created where compression takes place slowly as where the compressor is run at high speed; that is, where the pressure to which it is compressed is the same. The compressor heating more quickly when running at high speed may be accounted for by saying that a greater amount of air is compressed in a given time, and the heat of compression has less time between each stroke of the piston to radiate or leave the cylinder; hence, as more heat is created, and less heat radiated at each stroke of the piston, it is evident the compressor temperature must increase with its speed. Where the compressor is required to work against high pressure more power is employed than when working against a lower pressure; therefore, heat is generated at a greater rate. The temperature of the air before compression also affects the final temperature, as tests have shown that air at zero will have a final temperature of about 400 degrees when compressed to 100 pounds pressure, while air at 100 degrees, compressed to the same pressure, will have a temperature of about 575 degrees. The condition of the compressor has much to do with the temperature of the delivered air, and probably the greatest cause for heating is due to worn packing rings or worn cylinder. Where packing rings or cylinder are worn, air can leak by them in either direction; consequently less cool air is taken into the cylinder at each stroke of the piston, and the air leaking by the piston being of a high temperature, raises the temperature of the incoming air even before compression takes place. At each stroke of the piston the air that leaks by is hotter than in the previous stroke, and raises the temperature of the air still more, until finally the temperature of the delivered air becomes quite high. Thus it will be seen that to

arrive at a somewhat correct answer to your question there are several things to consider. However, taking a compressor in fair to good condition, making 140 single strokes per minute working against 130 pounds pressure, the temperature of the incoming air at 70 degrees will result at a final temperature of about 550 degrees. Defective air valves and partially stopped up air passages are also responsible for high temperature.

BROKEN EQUALIZING RESERVOIR PIPE

Question. Will you please answer the following question through the JOURNAL? While handling a train of 85 cars, the pipe leading from the automatic brake valve to the equalizing reservoir broke, and the brakes applied in service, making a nice stop. I have always understood that if this pipe should break, the brakes would apply in emergency, and I believe I have read that in the JOURNAL, So am anxious to know why the brakes on this train did not apply in emergency. What should be done where this pipe breaks?

A. L. C.

Answer. The breaking of an equalizing reservoir pipe will cause a sudden drop in pressure in the chamber above the equalizing piston, causing this piston to move up quickly, making a sudden opening from the brake pipe to the atmosphere; and with a short train would, no doubt, cause the brakes to apply in quick action. But with a longer train, having a larger brake pipe volume, the pressure will be reduced more slowly and the brakes will, as a rule, apply in service. When the pipe breaks, move the automatic brake valve handle to lap position, put a blind gasket in the union near the brake valve, and plug the brake pipe service exhaust port. To apply the brake in service, move the brake valve handle slowly toward emergency position, making a gradual reduction of brake pipe pressure, and when the desired reduction is made the handle should be moved slowly back to lap position. Where the brake pipe service exhaust port fitting cannot be removed from the brake valve for plugging, as is very often the case when desiring to make service application of the brake, move the brake valve handle to service position, allowing it to remain there until

it is desired to release the brake. When the desired brake pipe reduction is made (which will be indicated by the black hand on the small gauge), gradually close the brake pipe cut-out cock under the brake valve; a further reduction may be made by again opening the cut-out cock. When desiring to release the brakes, first place the brake, valve handle in release position and then open the cut-out cock.

"Helpful Hints on Modern Locomotive Brakes" is a book gotten up by our Air Brake Editor, Bro. T. F. Lyons. This book is up to date, and of handy, vest pocket size. Price, 50 cents. Address, T. F. Lyons, 546 E. 109th St., Cleveland, O. Editor.

Letter to Bill

Chicago, June 22, 1920. Deer Bill: Whatta ye think o th Raypubliken campane fer th nominashen av th prisidenshal candidate? I never seen th bate o it in awl me borrn days. I'm sure you didn't ayther. I never seen such bare face spinden av money in me life in a counthry thats dhry, "bone dhry," they say, whatever that manes, but it didn't mane anythin in Chicago durin nominashen week whin awl th candidates an thare heelers an rubbers an backers wur gathered thare fer th big race. The funny thing was the lads that spint th most money lost out whin it cum to th final contist, an than awl hands sed it wur a case o pure ould-fashend simon pure sterling quality av th winner that wun. At that th peepel cheered an clapped like childhren. Ould P. T. Barnum sed our Ameriken peepel like ta be humbugged, an he noo fer he foold thim a long time an thay liked it, an thay like it yet, so thay do. Bill, did you ever go to a cirkus an see th stunt pulld off whare a rube av a looken lad havin green whiskers, an hay in thim, an warin his pants in his boots, wud jump inta th ring whin the performans was goin on, an do awl th tricks th same as th klown an akrabats athout taken his boots off? Oh th peepel useta go wild over that. Er kin ye raymimber th races we useta hav at the county fares long ago whare thayd be an ould lad wud his pants in his boots, too,

like that kind doo, an him dhrivin a nag in the free fer all; a nag havin a lotta sand burrs in his tale an his mane, an he pullin an ould-fashend wood sulky, an it havin flat wheels anna cuppel o spokes outa aich wheel? An, Bill, dya ye mind how th dhriver never let an he noo a thing. If he wurth pole horrse heed cum down away aḥedda th feeld, er be way back, an finely the starter, looken like he wur outa pashence, wud holler th wurrd, "go," whin th rube layout wur way back, an th crowd thayd guy th dhriver an call him hayseed an holler giv yer nag more otes, er more ginger, er thayd tell him ta push on th lines? An thin th fursht thing weed no ould "Ruben" heed be up among thm. Round th shorrt fursht turn on th little half mile thrack hed hav th sulky ridin an th outside wheel, an thin down th back strech hed go by the showy hi steppers, wud thare fancy bikes an silver buckles, like thay wur meerly thare to ornmint th thrack, an bys o bys how heed make the lasht turrn in a cloud a dust, goin like a bat outahell, an wud th crowd yelling lik mad hed cum down th home stretch wud th bit in his teeth an pass undher th wire so far ahed o th feeld it wud luk like it wur goin th other way? That useta be grate, Bill, an alwus got a hand. I useta fall fer it meself, but th fact o th matther was th lad that ownd th hi steppers er mosta thim, ownd th rube outfit, too, but we didn't no that, an so what harrum, sez you.

So now, Bill, wud that race fresh in yer mind, let me ax ye ta kindly cumpare it to th late Raypubliken campane fer nominatin th presidenshal candedate, an if yer not as blind as sum think ye arre, ye kin see th same ould rube thrick plade agane whin Warren G. wun th nominashen. Dya mind, Bill, how Wood an Lowden wur paraden over th cunthry as big Wall Sthreet candidates long beefore th convinshen, an wherever thay wint thare wur a gang around thim throwin dollars away like thay wur thradin stamps. An dya mind how th noospapers got th peeple wurrkd up tellin about Wall Sthreet thryin to by th nominashen, an how thay krackd jokes about th hi costa nominashuns-fer so much a joke-an Wall Sthreet payin fer it awl. An whi thay had th peepel goin about

rite, thare wur a grate hullabaloo med fer a peepels chice candidate, an wud that the convinshen opened up an th contist wur pulld off on skedgel time. An thare cuddent be a place more fit fer a crookd deel av any kind than ould "Chi." Oh th convinshen race wur a grate job, Bill. It lookd like Wood er Lowden caus thay had th most money. Hi Johnson cuddent win caus Wall Sthreet wur afreed a him, an then thare wus Hoover an sum more that wur thare meerly to fill in so th crowd wud think it wur havin a run fer its mazooma. Wood an Lowden wur steppin hi as ye like an proud as ye plaze wud thare fancy thrimmins an rubber tire sulkys, so at the lasht momint afore th bell, in cums Warren G, like th rube at th cirkus er th kounty fare, an nobody thot he had as much show to win as a mud turkle. Annyways one oth gang throo th loded dice fer posishen an nacherly Warren G. got the pole, as is neerly always th case. So wud that, whin Lodge rings th bell fer th starrt, down cums th hole feeld, ahead oth pole horse, mind ye, an th californy inthry, Hi Johnson, goin bad. . At that Lodge, th starter, sinds thim awl back, an th nex time thay cums down ahed o th pole horse agane, an Johnson threatenin to bolt th thrack. That happened a few more times an Lodge hollers out that he woud fine anny dhriver a dollar an a half that wud cum down ahed o th pole horse agane. At that th peepel cheerd loud sayen that Lodge musht be a fare an shquare man, an then meerly to sho that he wur as fare as thay thot he was he sez, mad like, to th dhriver av Warren G., I want th pole horse to cum down wud th feeld, an on his sthride, fer we wanta pull off this race so th peepel kin get whats cummin to thim. After that bit o bunk, Bill, th hole krowd cheerd agane an sum lad sez, rite out loud, that th Ameriken peepel shud awl chip in an get a brown derby, er a dubbel cross er th like, fer Lodge, he bein such a fare guy.

An so, afther skorin nine times Lodge sez, to himself mind ye, we gave th crowd a good run fer thare money, so he gave a sine to th dhrivers ta be shure an make it a go nex time, an so the nex time thay awl came down like thay wur hiched in wan teem, pole

horse an awl, exceptin Hi, an whin thay passed Lodge he hollers loud, “go,” an thay dun so, an th crowd wint krazy, awl thim that wazzent krazy before. Yes, it wur a go at lasht, Bill, wud th candidates going sthrong upta th fursht quarther. All the crowd had thare eyes on Wood an Lowden an Johnson, no wan payen much attinshen to Warren G., fer thay thot he, like the rube at th county fare, didn't hava chance, an he wasnt payin attinshen to annyboddy ayther but huggen th pole like if it wur a months pay. Whin thay wur goin round th fursht turn Hi Johnson got goin bad agane, an he got Lowden excited so he wint inta th air, too, but Warren G. wur in his sthride huggen th pole, as I sed, an him at Wood's wheel an goin sthrong down th back strech, wud Lowden an Johnson an Hoover thralen in th ordher named, as thay say in th spoorting papers. At th third quarther th pace wur tellen on Wood-dee ya mindfer he begin to wabble like thay do, thin up he goes inta a bad break, an afore they cud get him back an his feet agane Warren G. goes by him like he wur a lode o wood er hay, an cums down th strech like a coyote an wins th heet an race th same as the rube that cum down the strech wud his flat wheel sulky at th kounty fare. An, Bill, th peepel wint wild agane an throo thare hats away, just as rekless as if thay wur thrown thare votes away, an Hinnery Capper Lodge med a little speech an sed th fakt that the candidates av Wall Sthreet wud awl th money behind thim cuddent win the nominashen over Warren G. wur a grate onner ta th Raypubliken parrty, an he sed that athout crakin a smile, too. Oh, Bill, he must be a grate joker. But joke er no joke I'm not kicken, mind ye, but meerly given ye a "close up" av th performance. No, Bill, I'm not nocken caus sum wan didn't show up th hole game afore or afther bein plade, fer th longer I live th more I see that Barnum wur rite, so whats th use o tellin peepel thare bein foold whin thare injiyen themselves caus thay dont no.

Ye no yerself, Bill, that whinever ye see a lotta peepel goin krazy wud joy over a fixd horse race or a nominashen it wud be rong to tell thim thay wur bein thricked, just th same as it wud be a sin to tell th childhren a

Chrismus mornin that Sandy Klaus wur a fake.

But annyway, whin th convinshen wur over every wan thare wur as tikled as a sucker whin hees payin fer his fursht goold brik, an thay awl sed Warren G. wur th goods, an that heed make a grate run, but beleev me, Bill, if he kin go fasther than a walk on that zig zag Raypubliken platform hees as handy as a tite rope walker, er a chipmunk. Yes, Bill, it wur a grate frame up an th hole thing inded in a blaze av glory, fer awl th wurld like an Oktober sunset on th Erie Canal. JASON KELLEY.

Questions and Answers

BY JASON KELLEY

Question. Would the sticking of a wedge, or driving box-whichever you please to call it-have any effect on track? I have never heard that it had, but not long ago I had an engine with a hot left main driving box and when the box got red hot it stuck between the wedge and shoe and the engine rode fearful and must have pounded the rail awfully. The tire was pretty badly worn. How would such a thing be likely to affect the track?

W. R., Div. 10. Answer. There is no condition the writer can imagine that is so likely to cause more damage to track than the very conditions brought out in your question. A much worn tire means, as a rule, a tire worn out of round, the main tires more so than the tire of any other of the driving wheels, and this condition finds its fullest development where the box is not closely fitted or where the wedge is not kept in good adjustment, both of which are common faults today.

So with the main wheel worn out of round and the box stuck, thus supporting rigidly all the weight of that side of the engine, it is easy to see how the continuous pounding on the rail that such a condition would cause, must surely have a very damaging effect upon it, and the track in general.

Question. What is the reason we have trouble here on our superheater engines with piston packing? It will sometimes go all right for a while and then blow out and new rings will do the same. On some engines the packing