Arizona republican., 1921-05-22
TREAT YOUR REAR
 AXLE TENDERLy.
By GEO. x. AUST

Among the hardest working units in the mechanism of the modern motor car is the rear axle. The function of this part is not only to help carry the weight of the ear but also to transmit the power. When ever the car is in motion the rear axle is the scene of intense mechan- ical activity. It will be obvious. then that this part of the mechanism should have the most scrupuious care. It does not always get il. as we shall point out in the course of this article.
 Rear axles fall readily into two dis tinct classificationS, dead axles and live ones. It is live axles which are used on all modern passenger cars, The term live simply means that the axle turns. Dead axles do not turn and they are only used on ve- hicles having double chain drive.
 When we come to examine live axles we find it necessary to classify them still further into three minor classes, known respectively as float ing. semi-fioating and three quarter floating. A further classification comes later. according to the type of gearing used to transmit the power.
 The live axle consists principally of a hollow spheroid from which pro- ject on either side two tubes In the central spheroid is located the diff ferential unit embodying a number of gears. From the differeltiai pro- tubes projecting from the central spheroid of the rear axle. At the ends of these shafts the wheels are attached.
 The classifications of floating, semi floating and three-quarter floating are derived from the method used in attaching the wheels to the shafts.
 The floating axle does do very nearly that thing. It is not called upon to bear any of the weight of to the wheels and takes a little of the torsional or twisting stresses. The floating. axle has its bearings outside the tube, so that the wheels really rest on the tubes and not on the shafts. In this type of axle the shafts may be removed without dis i turbing any other parts.
 The semi floating axle has its bearings on the inside of the tube, SC l shat the shafts are called upon tc bear some of the load as well as tc transmit power. The shafts are not as easily removed as in the case oi l the floating axle.
 The three quarter floating axle has the bearings on the outside of thu i tubes and there is a rigid connec- ton between shafts and wheels. This l type demands that the shafts shal bear some of the load in addition ts transmitting power.
 When it comes to the types O. 1 gears used in transmitting power WI l find that the passenger cars of to- day employ three, straight bevel spiral bevel and two speed hevel. II l the truck field we find three addi. l tional types, the worm internal geal and double chain drive, though tn, latter is growing less every year During the last few years the spira beve1 has come rapidly to the front 1 until today it is the most populal 1 type. There are obvious reasons foi l this, it's quiet running and genera efficiency being the leading ones Many makers still stick to tn
 straight bevel, while the two spec,
 bevel has only one prominent adher
 ent.
 The car owner who has exper
 fenced, that most tenacious troubl
 commonly known as rear axl
 trouble will not need the advice l.
 do everything possible to guar,
 against it. Many serious trouble
 may develop in this unit and oni
 the utmost care will obviate some O them Axle shafts sometimes breal
 or are twisted out of their prope shape. Bearings are sometime crushed. The differential gears ar peculiarly liable to chipping, whic may very probably result in the rui of the whole unit.