Arizona republican., 1920-07-25
QUESTIONS AND
 ANSWERS

Q.-When they say that a car has a unit power plant what do they mean? find this term used in the automo- bile page and I don't understand it.
 A-The term unit power plant is used to describe the construction wherein the motor and the geat set housings arg integral. Other construc- tions make the gear set a unit with the differentiai housing on the rear axle, or give it a separate location midway between the motor and the rear axle.
 Q.-My car has just gone to the re- pair shop to have a set of broken tim ing gears replaced. The relative cost Illness of the proceedings leads me to ask you what causes breaking Of tim ing gears?
 A-Imperfections in the metai may cause timing gears to break and so may misalignment, due to improper installation or the warpage Of the gears. This latter condition may be induced by running without oil or in oil containing fragments of metal in the oil from the gears.
 Q.-will it be possible to increase the power of my engine by fitting a plate of some sort on the top of the pistons, thereby increasing compression? What material ought the plate to be of and how thick should it be?
 A.-Yes: you can undoubtedly in crease the power of the engine by rivetting on the tops of the cylinders, aluminium plates having thickness of from one-eighth to one-quarter of an inch
 Q.-I have bent the front axle of my car slightly, in a curb slam. Do you think it is likely that the wheels are out of line What had I better do? Alt is extremely likely that the wheels are out of alignment. Never l fail after an accident of this kind, to have the alignment checked up by a reliable repairman, if you cannot do it 1 yourself Don't delay attending to this, as wheels misaligned will cause excessive tire wear, to say nothing of l the difficulty of steering. which will be noticeable.
 Q.-Will you be kind enough to tell me what the difference is between the so-called selective and the progressive gearset?
 A.-The essential difference is that l in the selective gear set any speed may 1 be obtained without first going into any other speed. In the progressive type high speed cannot be obtained
 without first going through the lower speeds.
 Q.-What is meant by gear reduction on high?. What relation has the speed of the motor to its power and perform ance?
 1 A.-The term gear reduction refers 1 to the ratio between the number of
 teeth on one gear to those on another
 gear. The gear reduction on high is the ratio between the number of teeth
 on the differential ring gear and the
 driving pinion. Thus to l means that
 there are three times as many teeth on
 the ring gear as there are on the | pinion. This means that the engine turns over three times to one revolu-
 ton of the rear wheels when the gears are in high. 2. As the engine speed
 increases the power increases up to a certain point called the peak. At this
 point the engine has reached it's maxi mum power although the speed may be
 further increased.
 Q.-I have a great deal of trouble
 with my engine driven tire pump. Even
 when new the pump was little good and I have about come to the conclu- ' sion that the hand pump is best after all. Moreover. 1t is a nuisance to be I lifting the hood and making connec-