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Show &Auimnik mplkd By an Automobile Expert. If there Is anything not clear to you, ask the automobile editor about it. An answer will be published on the co mpletion of the articles pertaining to each section under discussion. - I LESSON NO. 17. The Cooling System ! The gas engine, known to engineers as an internal combustion engine, comes in the class of engines known as heat engines, because of the fact that the power is derived from the heat developed devel-oped when the mixture of gas and air explodes, or burns. As heat means power, pow-er, all of the heat practical must be kept in the engine. Unfortunately, if the metal parts of the engine be allowed to reach a certain tern- , perature they will become soft, and as they must rub together, the metal would soon be cut and- so the parts be ruined. Thus the engine must be equipped with some device which will keep these metal parts below this dangerous temperature. In other words, a cooling system must be furnished in order to keep the cylinders from becoming so hot as to be cut and ruined by the rubbing of the reciprocat- 1 ing pistons. Both air and water are used to cool the engine. Where air is used alone, flanges or rings are cast around the cylinders, which flanges will conduct the heat away from the cylinders, the heat, In turn, being taken from the flanges by a blast of air, which is blown on them by means of a fan. By observing the engine en-gine on most motorcycles you will he able to see how these flanges arc cast on the cylinders. When the engine is water-cooled, a jacket (as shown In the illustration and called a water jacket) is cast around the cylinders and water is then made to circulate through these jackets. As the ! water comes in contact with the metal 1 it cools it, but in doing so it will take ! the heat to itself and thus become hot. i So, unless the water also be cooled it would in time become so hot as to be useless as a cooling medium for the cylinders. cyl-inders. On a stationary enctne a stream of water from the city piping ran be used, but on a moving auiomobflo the same water must be used over and over nsjain. In order to cool this water it is led from the cylinders to the top of a coolins tank called a radiator throneh whirh it slowly flows downward, being cooled on t he way down by air which is sueked through the radiator by means of a fan. There are two methods employed to make the water circulate through the water jackets and the radiator. In on of these a pump, set almost immediawlv in back of the radiator, sucks the cabled water from the bottom thereof and then ; fortes it through the water jackets and; up to the top of the radiator, down J through which ft then flows .by gravity, i beinir cooled on the way down, when it; !s a an in pumped through the Jackets, j ! et' This is called the pump system, and I is shown In figure 1. 1 1 Tre other system, called natural rir- ; jCulation. or thermo syphon system, de-i de-i pen.is for t he circulation on the fact th:it, 1 hot water being lighter than coid wnter. : : will set to the top and cold water to j tlie bottom. Thus, when th engine is . running, the water in the jackets will ; 1 become hot and so travel upward to the ! ; top of the radiator, its place being taken; by the cooler water in tlie hot. torn of it. j I There are two types of radiators, tnbii- ' . lar and ceMular. or honeycomb, j Figure :i shows a tubular radiator. ! I This, yon will notice, consists of a crrrat ; ' number of vertical tubes, about whjh are J placed a !;ir;e number of thin meia! i 1 fiances. As the water flows t hro-.ich : i these tubes the tubes hp"om hot rind j j ;h:r heat is then conducted awav bv t;-;ej ( flanges. These flanges ar in turn, cooled : j by air Which is sucked through thm bv ! I a fan generally rlrtced Immediately in bark of the radiator. Cm some, older I cars the spokes of the flywheel act as j the fan. i Figure A shows a sMon of a rel'u'ar 1 radiator. Here the water pa.css through ! ! two thin sheets of ir.e;;i!. vhj.-h micl-t ' , he ienr.ed a very !-:::. h-t w.de. tube. s I : that the water travel? dowr.vayd in an eit jcdir.gly thin stream. Xa o;iVa Uus j stream as long as possible the sheets are bent in a zig-zag way. as shown In' the illustration. The corners of the zig-zag sheets are soldered together, bo that the radiator gives the appearance of a honeycomb. The space between the tubes will form cells through which air is drawn by the fan. The cooling- system of a car is an extremely ex-tremely important part thereof, as without with-out it the engine would soon be ruined. A word as to tlie care of It: Each morning the radiator should he filled with fresh water. Because bubbles or air pockets often form in the Lop of the radiator, looking in to see the level of the water may result in your believing believ-ing that the radiator is full when, in fact, it is not, so it is beat to actually pour some water in. In the winter time, if the car is used, an anti-freezing mixture should be used with the water. Denatured alcohol is perhaps the best, and this can be used in the following proportions: 25 per cent alcohol, 75 per cent water freezes at zero; 30 per cent alcohol, 70 per cent water freezes at 5 degrees helow zero; 40 per cent alcohol, 60 per cent water freezes at 20 degrees below zero. In time the alcohol al-cohol will evaporate, so once a month a little should be added to take the place of that which has disappeared. (Caution (Cau-tion In putting the alcohol in the radiator radi-ator be careful not to let any spill onto the varnish, as. it will eat the v3xnten quickly.) When the car Is not used In tho winter, the water should be drained off. In do- ; ing th's it is Is important that the sys- tern be studied to see if there are any 1 places where some of the water can be j pocketed and not drain off, especially at 1 the bottom of the water jackets. Many ! a cylinder has been cracked because of a , failure to do this. I Today there i little likelihood of a leak in the system developing, and when ' it does it usually is at the rubber hose 1 or around the pump shaft. To prevent leakage around the pump , shaft, the pump is furnished with pack- ing nuts, as shown in Figure 2, JjaiuT 1 wick, or, preferably, some special pack- I int? material, is wrapped aiound the shaft ! and the nut then screwed cn, thus squeezing squeez-ing the packing around the shaft and so preventing the water from leaking out. Wnen the pump is first packed, so much packing must be used as to make the pump light when the nuts A and R are screwed up about half way; then, as the 1 packing wears away and the pump leaks. I if the nut? he tightened a little tlie lefik- age will disa ppear. When tlie nuts are screwed on full way some more packing must be added. The radiator is always coupled to the j ' rest of the system by a flexible hose, as If 1 i it were ricidly connected a leak would soon develop, due to tlie vihration. The j ; writer believes In repiainc the hose once ! a year, as it will rot on the inside, and ! yet appear perfect on (hp outside. 'YVh"ri j the hose is rotted, lb1 inr.fr rubber will , -nme loose and oftfn seriously cherk ih; , '"ir.-uia tton of the walfr. When new hose is put on it Is a pood practice to put i some sheila--- on tlie ripe to whirh it is 1 attached, as the shHIac will do nun-h t" : prevent a leak between (lie hose andpipp- ! A larre proportion of overheating is j due to a slipping fan-belt. In time a belt I will stretch to su'h an extent as to slip j To take care of this flip, practically all) '"ars have the fan and its pulirv mounted i in sur'i a wav that they fan be set farther awav from the driving pullev ;md in this way tighten the belt. There is always more or ir-ss lime in the water, and in time this l.nie w-, be ! deposited on tbf jacket an.! radiator v.-;i1If j in the form of n s-aio. As i: a r.or I condu.-tor of hear it will materially affect I the cooiinc. About once everv two or! three months the water soulr be drained out of the system a nd f iesh water, in j which has b f- e n dissolved s m t s o i a i n j he proportion of about a hnniful to r bucket, be pourei In. The eiu'.ne shn-:ln 1 :h'n run a wh:le (bni:- st:ii. ; rnr bp driven ;i few mip) aur this solution thfn drained o:T. The py---, rr;--' ii -:i be ffus'-id n-:t a nirmVer of t:m'. with , fresh naiar. U. engine he.r.g run a mo-. ment or two so as to make the water circulate. This flushing must be continued con-tinued until tlie water Comes out clear. |