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Show . . THE MODERN AUTOMOBILE By George Bergstrom, nstructor Auto-Meduinics, Ogden High School. Written egieciallv for The Stamlurd KxamimM maM . II in I IN M DRI I GROl P , B In this most Important pan of the , - fl i modern car. we have many different ' units, and the final drive group usual - 'ii Iv begins from the trsinsntsslon. In il! v that the transmission 1s placed on the H. 9 rear ajile Itaelf, it makes Put little dlf- S ference. and this unit will bo discus- B 3 Md in another article. H; jf' with the universal Joints, drive shaft. H,!!!! ear reduction thVoueh the drle shaft 1 ' pinion and ring gear, rear axle houi H:.rf,'r ings. axle shafU, differential. toripe H : 1 and torsion rods and otln r small units Hi 1 such as brakes, wheels, etc (1 I The drive shall of the car trai l.f 1 the power from the transmission to i ihe rear wheels through Ihi medium .J i of the universal joints, which allow ii the drive shaft to transmit the power at arty angle. It is so constructed that, B no matter what position tlx- drive Hl ' " shaft Is in. the unlvcr.-.il J.iints moe H!. II t- kto compensate this angle. The con- ; tlnual moving up and down of the n 1111 axle In its work of driving the car. I : 1 ! Us sideway or its lack of alignment. Is jj taken care of by this Joint. J, r There are two types of nnn r al i joints pni iit is stationary and thp other a slip joint. The latter allows I fore and aft movement of the drive shaft. This is done by having one end - ' I of the universal joint with square opening and one end vf shaft squar-!;; squar-!;; ed to fit It This end of the shaft la machined to fit the unlvciisal joint and I Peing 6quarc. II drives, and at the lairie time slides In Vr out as the occasion J requires, and does very effective work. There are other flex -iJc drives ut- i. 6uch as two thin pieces of tempo ! ateel. leather Joints, also many heavy i lajcra of fabric bolted together. The drive shaft itself is somdttmea 1 called a propelb I made with a universal joint at each , end, not very large In diameter and of n I j solid steel. It is held Wmi-ilgid bj a !j torque arm or tube, which koe'ps It j in alignment wiih the frame cf the i i car and eounteraets the effect of I torque caused by the twisting ton t ol 1 the drive shaft. The final reduction is obtained by ihe us- of gears. These may be of everal type, such as the bevel spur gear, worm gears, helical gears, and spiral bevel gears. The smaller one or the pinion Is fastened to the drive shaft, and meSheS with a larger one thai Is Listened on the housing of the differential. The drive shaft turns BJ the same rate of speed that the motcn- does When II hi In direct or high (ear. The pinion turns at the same peed. If Ihe elie- shaft pinion has ten teeth. 'the ring gear or the larger one has foity teeth, the gear redud- tlon would be at Ihe ratio of four to one. In other words ih- wheels will turn once while the: motor makes i...ur complete reve.lullons. The worm gear is not very suitable fOE,pleasurs ears, or ones than have to travel at high rates of speed. It ha- a much larger gear reduction, and i more suitable for trucks and small e 1,-ct rle i .i rs. The axie bousing Is made as a covering cov-ering for the differential and carries I a good part of Ihe we ight or the load. In addition, brakes, wheels, rods. etc. I are fastened or bolted to I' 1 The differentia was devised to allow I the wheels on the rear to turn at ctif-I ctif-I ferent ratios of speed. This was ne-icessary ne-icessary because the- car in turning .-, 'comer or otherwise-, needs a balan as a compensating gear. This mech-( mech-( nlsh which allows em. whee.-l to turn j faster than the other must also gh'-a gh'-a positive elrle- to the motor. In or- der that a car may go around a curve properly the outside wheel munt turn (at a greater rate of speed than the j inner cene, in fae-t. the Inner one holds a pivot, us It were, and the outer one j must travel just that much faster In lb.- same Interval of time, rhls i- dote b3 a ne-t of cltlie r spur or be vel gears. Thi- set of eais Is held together so j that when imre resistance coine-s on 'one wheel than the other one-, this one , will slow down or stop ami the other one will speed up In proportion i To He- Continued i |