ing set manufactured by the Pyle-National Electric Headlight Company known? A. The type "E" equipment. (Art.

1.)

2. Q.-How is the dynamo protected from mechanical injury and weather conditions?

A. By being self-contained and enclosed. (Art. 1.)

3. Q.-How many rows of buckets has the turbine wheel, or rotor?

A. It is of a special tension spring type and operates the valve by means of two levers. (Art. 2.)

6. Q.-What speed is the tension of the spring set for, and how may the speed be increased or decreased?

A. The tension of the spring is set for the required speed, 2,800 revolutions per minute. The speed is increased by turning the adjusting screws, 617, to the right, and is decreased by turning them

used.

(Art. 2.)

7. Q.-Why is it necessary that the port openings in the governor valve cage should register with the 3-inch steam inlet hole in turbine casting?

A.-Because, were it inserted with the blank side covering the steam inlet, steam could not pass through to the nozzle and wheel. (Art. 2.)

10. Q.-What form of bearings are used with this equipment?

A. An annular ball bearing is used on the generator end, while a special bronze metal bearing provided with an oil ring is used on the turbine end. (Art. 3.)

11. Q.-What lubrication is necessary with this equipment?

A. The only lubrication necessary is

8. Q.-How is the travel of the governor valve regulated, and what should the opening between the valve and seat be?

A.-Adjustment is made by means of the two nuts, 615 and 618, on bottom end of valve stem. The opening should not exceed 1/16-inch. (Art. 2.)

9. Q. What effect does the adjustment of the governor valve have, and what other adjustment is necessary for speed?

A. The adjustment of the governor valve only regulates the speed at no load, that is, with the arc lamp not burning. For all speed adjustment the adjusting screws, 617, located on the

at the two bearings, which may be accomplished by means of two oil cups in which a heavy oil such as valve oil, should be used. (Art. 4.)

12. Q.-What attention should be given the oil cups to insure regular lubri cation?

A. They should be examined each trip. (Art. 4.)

13. Q.-What should be done in case the equipment should be taken out of service for a considerable length of time?

A. In order to prevent corrosion of the parts, one-half pint of ordinary engine oil should be introduced into the exhaust opening and the shaft revolved a

Engineer McGinniss showed up in the air car the other day for the first time in a long while. He has the 32d degree in air brake philosophy and is a divinė critic, and I had a hunch that he was due to start something; which he did. "I don't wish to be understood as finding fault with your instruction work, either locally or in your published articles, but merely want to correct a misstatement of fact," he began-and that was rather mild for McGinniss-nothing like a cold shower bath to start the circulation. "You have cited a case in a recent article in which a passenger train was composed of five cars with the common PM brake equipment-ordinary quick-action brakes and the sixth and rear car, a sleeper, had the new 'PC' brake equipment. The feed valve on the engine being in sluggish condition the maintenance of brake-pipe pressure was irregular, and the circumstance is supposed to have occurred and repeated itself, wherein the drop of brake-pipe pressure while the feed valve was sticking shut caused the brake on the PCequipped sleeper to creep on, while yet none of the PM brakes were affectedno other brake stuck.

"Now," McGinniss advised, "it is my understanding that the 'control valve' which in the PC equipment takes the place of the common triple valve, is less sensitive than the triple valves on the PM-equipped cars in moving to application position from reductions caused by brake-pipe leakage in connection with sluggish acting feed-valve on the locomotive, and has just the opposite effect to that which you relate in your article. This feature has been embodied in the control valve with a view overcoming the troubles you mention in the magazine article I have referred to. The release piston will move down promptly and close the charging ports

of

on a light brake-pipe reduction, but the brake-cylinder exhaust is not closed, and the brake does not apply until a predetermined amount of brake-pipe reduction has been made, which is about 5 to G pounds.

"If you meant to infer that the 'L' type of triple valve was more sensitive than the ordinary kind and would give the trouble mentioned in your article, it would probably have escaped my attention," he concluded with his finest missionary air.

From McGinniss' particular perspective he was right, but with practical reference to the underlying issues in the article he referred to he was wrong. However, there may be other engineers in passenger service who, like McGinniss, have missed the lesson intended in the printed article referred to, by having been too exclusively interested in the reference to a PC brake applying from a brake-pipe reduction which, in the case in question, did not apply any of the brakes of the old standard equipment; and, as a consequence, some of those engineers may be led to do their braking of PC-equipped cars in a manner not calculated to produce the best results. So, here is a good opportunity to repeat the instructions of the Westinghouse Air Brake people regarding the proper manner of doing service braking where one or more cars in the train have the PC equipment.

It is a common practice with some passenger engineers to start a service brake application by a reduction of only 5 or 6 pounds, this usually being sufficient to start the triple valves into action and to get the brake shoes against the wheels with just about force enough to gently close or run out the slack between the cars in the train, following this up immediately afterward with a heavier reduction that will afford the re

quired braking results-a very good method of practice where all of the cars in the train have the "PM" equipment, or "L" triple valves with the graduated release feature cut out.

The "control valve" of the PC equip ment, however, is so devised that a 6or 7-pound brake-pipe reduction is required before it will start applying the brake; hence, with a train composed of PM-braked cars with triple valves, and one or more other cars having the PC equipment and control valves, a 5- or possibly a 6-pound reduction would probably cause an application on all of the PM-braked cars, but would not apply the PC brakes. If the PC brakes were at the rear of the train, for instance, this would cause a bunching of the cars with the compression of the draft and buffer springs; consequently the following reduction would then apply the PC brakes at the rear, resulting in a violent stretching of the train which I would be intensified by the reaction of the draft and buffer springs. With the PC-braked cars ahead in the train, equally violent shocks would be induced at the second reduction through the sudden closing of the slack and the bunching of the cars.

To do the braking so as to avoid these troubles, whenever there is one or more PC-equipped cars in the train make the first reduction by drawing off never less than 8 pounds; this will cause all brakes in the train to start taking hold, and if the PM brakes have proper piston travel -if those cars have the automatic slack adjusters the cars having all styles of brake equipment, PM, LN and PC, will all apply with approximately the same relative degree of power.

The control valves are designed to require a somewhat greater number of pounds reduction before they start brake application than is necessary to apply the triple valves, so that any fluctuation of brake-pipe pressure-that is, any reduction-within certain limits, will not cause the PC brakes to creep on.

But engineer McGinniss confused pounds reduction with something vastly different-the rate of reduction of the brake-pipe pressure. Here in the air car I have frequently closed off the air pressure supply to the instruction rack and then bled the brake pipe down a matter of 20 pounds or more, but so slowly that not a triple valve in the rack was moved to apply the brake.

There have been many instances where air pumps have failed on the road, or angle cocks have been accidentally closed, and the brake-pipe pressure has escaped completely in a comparatively short time, without applying a brake; for there are the feed grooves in the triple valves, and the leakage grooves in the brake cylinders to waste the auxiliary-reservoir pressure and prevent an application when the reduction of brake-pipe pressure is very gradual; and the better condition the triple valves are in, the less is the likelihood of the brakes applying under the circumstances.

On the other hand, what would be the result from a control valve in the PC equipment, in case of a slow decrease of brake-pipe pressure of 8 pounds or more? On page 245 of the Proceedings of the Air Brake Association at their 1911 Convention, in a paper prepared by the Chief Engineer of the Westinghouse Air Brake Company and read before the association members, on the subject of the PC Brake Equipment, we read in the details of its "novel functions" that one of those most important functions is:

"Certainty and Uniformity of Service Action, secured by insuring that the valve parts move so as to close the feed grooves on the slightest brake-pipe reductions, the design of the valves being such as to then cause the necessary and proper differential to be built up to move the parts to service position as the brake-pipe reduction is continued."

Therefore with a slow falling of the brake-pipe pressure it is only a question of amount of reduction until the PC brake applies; while the PM and LN equipments require a certain rapidity as well as a definite amount in the pressure reduction, before their brakes can apply at all.

In

I explained this to Mr. McGinniss. And an idea then occurred to me. the coach tracks, and having just emerged from the shops, were standing a train of five coaches, combination and parlor cars all with PM brake equipment, and the sleeper Sanjack equipped with the PC brake. I took Mac with me, we went over to the coach yards and had the air cut into that train. At the end of the train where the air pressure was connected I inserted between the hose couplings a special fitting with air testgauge to indicate the pressure in the brake pipe of the cars, a cut-out cock,