The Motor Drivers News.
Page 25
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A Faulty Design of Pump.
" S." (Bath) writes :—" We have lately had considerable trouble through the engines of our buses steaming and getting very hot. The cause of this I first put down to the radiators, because they have no head of water, but, when this was remedied, the result was not much better. The radiators, however, did not steam when new, or when they had just been cleaned out; therefore, I went to work to find out how it was that they should get out of order so soon. I knew that the only place where grease could get into the radiator was from the circulating pump arid, on examining the pump, I found that the packing gland was in such a position that, when the grease cup was screwed into the bearing, the packing would not allow it to escape, but forced it directly into the pump and, from there, it got into the radiator tubes. This, of course, did not give the radiator a chance to cool the water. To remedy this, I had the pump bearing bored out, and the packing now comes on the inside of the grease cup, and, therefore, forces the grease outward instead of inward as before. The attached sketches will make it clear how I altered the pumps, and the result will be apparent to any engineer."
The Use of the Engine as a Brake.
" SOB." (Flampstead) writes It seems to me that
very few of the drivers of trade vehicles, or omnibuses, have any idea of the powerful means of control that they have at their command—the use of the engine as a brake; this applies especially on hills, no matter how steep they are. As far as my experience and observation goes, the usual practice is, on corning to the brow of a hill, to let the vehicle get a good way ' upon it; take out the clutch suddenly, and cram on the brakes. This nearly stops the vehicle, so off come the brakes again. Then another little spurt of speed, to be checked again by the brakes. This goes on until the bottom of the hill is reached, when the clutch is again suddenly applied. Things go on as usual. This method works all right sometimes, but, now and again, it works all wrong. Take the recent accident on Sunrising Hill for an example. These incidents are bound to occur when the ` brakes fail to act.' (This is according to the driver, if he is lucky enough to be alive to tell the tale afterwards). The trouble really lies in the fact that the vehicle is out of positive control at the top of the hill when the clutch is taken out, and it is allowed to make a little rush for a few yards before being pulled up by the brakes. If it is desired to run down the hill on the brakes, the vehicle ought to be brought almost to a standstill before commencing the descent. Then, let it run down easily on the brakes and not, as nine out of ten drivers do, bring the vehicle nearly to a standstill with the brakes. A safer, more comfortable, and dignified method of getting down a bad hill is to ease up at the top, change into first or second speed, and keep the clutch in. Next close the throttle about three-parts of the way, and go down the hill at a comfortable pace. It is immaterial whether the ignition is switched off or not, except that, if it is kept on, it is not forgotten when the vehicle needs a little help from the engine, which can be done by opening the throttle a little. When coming downhill by this method, the clutch should not be touched at all, and no attempt to change the gears should be made.
" I recently had to test a 2-ton lorry and tune up the engine previous to its trial by the purchasers. The load was made up of two tons of pig-iron, and for the brake tests I headed for Netherhall Gardens. I adjusted each of the three brakes to do its work by itself, then made the whole descent on each brake in turn, and then I gave the engine a chance to see what it could do in that respect. I found that in the
lowest gear with throttle closed we only just crawled down. With throttle fully open the engine still had its own way and kept the speed about equal to that on the level with that gear in. In second gear the engine still ` took charge,' but, in third gear, the weight wanted matters its own way, a little more and I had to check it with the foot brake in order to take only my share of the Firichley Road at the bottom. By the way, I did not go round 14•rognal to reach the top of the hill each time ; I drove up Netherhall Gardens."
The Care of a Boiler.
" G.G." (Bradford) sends the following letter —"I took great interest in the letter from (sVatford), especially as we are both in the same line of work, that is brewery ' work. This class of work I consider the hardest that a steam wagon can be put to, as sometimes the load has to be delivered at four or five different places. The boiler gets all the hard work. At every stop it Must be quietened down and the fire damped back to a certain extent, as, usually, the wagon has to stand in the public road during delivery of the load, and it would not do to have steam blowing off,' even if the stop was for only a few minutes. I am told by boilermakers that rapid changes in the boiler pressure cause much more straining than if the pressure were fairly equal all day, as it is on a day's journey with one place of delivery. I cannot say that I, or a great many drivers of my acquaintance, agree with 4 F.W.' about blowing a boiler down or drawing all the fire at once, and, of course, the fire must be completely drawn before the boiler is emptied or it will be of no more use without extensive repairs.
" I was taught boiler management by an old man who had 4o years' experience with all types and his method is surely to be relied upon. On reaching the depat at night clean the fire thoroughly but leave sufficient fire in the fire-box to cover the bars. Sweep out the tubes, put the damper down, and fill the boiler well up, shut off the stop cocks on the pump and injector, and, if the engine is standing outside, put a bag, or something that will answer the same purpose, over the chimney ; this keeps rain from dropping down the chimney into the smoke-box, and rusting whatever it comes in contact with. On lighting up the lire next morning, remove dead ashes, and then light the fire as usual. When there is between 30 and 6o lb of steam, open the blow-off cock and blow down to half a glassful of water. Then shut off the cock.
"The reason for not blowing off' the water when coming in at night is that the water in the bbiler is in a state of commotion owing to travelling, and the particles of scale are floating about. By the following morning, however, the sediment has settled to the bottom of the shell, and is swept out when the blow-off cock is opened, which would not have been the case overnight, unless the boiler was completely emptied. This is a very bad practice, as the strains set up by sudden contraction are very great; it should never be done when the boiler is under steam pressure. Should it be found necessary to change the water in the boiler, the steam must be knocked down to zero, and, then, if there is not sufficient time to allow the water to cool off, the blow-off cock can be opened slightly, and at the same time the clean water can be passed in through the tilling plug at about the same rate as the dirty water is running out. When the water comes out clear from the blow-off cock, it can be shut and the boiler filled to working level again. By doing this, the boiler is cooled off gradually, which is a big point, and the water changed just the same. " I should be very pleased if some fellow-driver would enlighten me as to how to cure my water-glass; it is of the Klinger type, and for some time it has been very difficult to tell where the water level is. I had the glass out and cleaned it and the fittings thoroughly; everything is free from grease, and all the passages are clear and the boiler is perfectly clean. The top half of the glass is all right, but the bottom half is discoloured. I am completely at a loss as to what is the matter, or how to cure the trouble, which, as will be realised, is a somewhat serious one, in view of the possible results from want of water in the boiler."