MOTOR CAR 



5556 



MOTOR CAR 



the transmission. When a pedal 

 is released and a strong spring 

 allowed to press the parts together, 

 the connexion is made, and the en- 

 gine drives the mechanism beyond 

 the clutch. Pressure on 

 the clutch pedal throws 

 the clutch "out" and 



Motor Car. Fig. 1. Dia- 

 gram of self-starter. See 

 text 



frees the engine. A common form 

 of cone clutch is shown sectionally 

 in Fig. 2. Engine fly-wheel A, 

 fixed in crank-shaft S, has a wide 

 rim, slightly coned inside. Clutch- 

 plate B has a wide rim coned ex- 

 ternally on the same taper as A, 

 and covered with leather, riveted 

 on. (In some clutches the leather 

 is attached to the fly-wheel.) B re- 

 volves on an ex- 

 tension of S. Nor- 

 mally B is forced 

 into A by spring 



Motor Car. Fig. 2. 

 Details of cone 

 clutch. See text 



S P, and the engine power is trans- 

 mitted through C from shaft S. To 

 disconnect the engine, B is drawn 

 slightly to the right by fork D of 

 the clutch pedal, out of engagement. 

 A multiple clutch is illustrated 

 by Fig. 3. Fly-wheel A, crank- 

 shaft S', and casing B are bolted to- 

 ether. Drum C is fixed on shaft 

 2 , B is grooved lengthwise inter- 

 nally ; C externally. The ring-like 

 plates P (marked in solid black) 

 are so shaped that alternate plates 

 fit B and C respectively and are 

 carried round by them, though 

 able to move endways. Spring S P 

 forces in cup D and presses the 



plates together against a flange on 

 C, and the total friction makes the 

 whole clutch revolve as if solid. 

 If pressure on D be relieved by the 

 pedal the plates fall apart. 



The single-plate clutch, having 

 a plain or asbestos-covered flat 

 disk forced into contact with a flat 

 surface on the fly-wheel by a system 

 of three levers, also enjoys a con- 

 siderable vogue. 



THE GEAR Box. The petrol en- 

 gine, being essentially a high-speed 

 motor, must revolve much faster 

 than the road wheels, and, as its 

 power falls off 

 rapidly with th e 

 rate of revolution, 

 means must be pro- 

 vided for altering 

 the gearing-down to 

 suit the running con- 

 ditions. On the level 

 it may suffice if the 

 engine crank-shaft 

 turns four times for 

 every revolution of 

 the road wheels, 

 since under this con- 

 dition the car can 

 easily be moved fast 

 enough to keep the 

 engine speed high. 

 But when a hill is 

 encountered, the 

 greater resistance slows the engine 

 down, and reduces its power just 

 when it is most needed. The 

 driver can, however, alter the gear- 

 ing by the movement of a lever 

 so that the engine may make, say 

 6, 11, or 16 revolutions per wheel 

 revolution, and get in a larger num- 

 ber of power strokes during every 

 ten yards the car progresses. The en- 

 gine is thus enabled to do useful work 

 at the same rate as before, though 

 the velocity of the car is reduced. 



Most change-speed gear boxes 

 are next to the clutch, and give 

 three or four different speed ratios, 

 besides a reverse gear. The last is 

 essential, since a car engine is de- 

 signed to run in one direction only 

 and it would otherwise be difficult 

 to turn big cars in narrow roads. 



The principles of a four-speed 

 box are explained by the accom- 

 panying diagram (Fig. 4). Shaft 

 A, driven by the 

 clutch, embraces 

 shaft C, which 

 projects from the 

 rear of the box 

 and will hereafter 

 be termed the 

 gear box shaft. 

 To A are fixed 

 pinion D and the 

 internally - 

 toothed ring N. 

 The lay or inter- 

 mediate shaft B 

 carries fixed 



Motor Car. Fig. 3. Dia- 

 gram illustrating multi- 

 disk clutch. See text 



pinions E (meshing with D), L, H, 

 and F. Pinions M, K, and G 

 (the two last joined together) re- 

 volve with C, but can be moved 

 endways on it in either direction by 

 forks in collars X Y, forming part 

 of the gear-changing mechanism. 

 As shown, all the sliding pinions are 

 in their neutral positions, and A 

 and B are able to revolve without 

 influencing C. To throw in the 

 first speed, K G are moved to the 

 right, and G meshes with F. For 

 second speed, K G are slid to the 

 left, and K engages H. Third speed 

 is obtained by mesh- 

 ing M with L ; and 

 the fourth speed, or 

 "direct" drive, by 

 slipping M into N, 

 thus locking A and C 

 together. Reversing 

 is accomplished by 

 means of a special 

 pinion (not shown) 

 which connects F 

 with G. The three 

 forks by which the 

 forward and reverse 

 gear sliding pinions 

 are moved are at- 

 tached to sliding 

 rods, with notched 

 lugs on their upper 

 sides. A short arm 

 projecting from a shaft turned by 

 the gear-changing lever can be 

 moved sideways into any of the 

 lugs. " Gates," or openings in the 

 lever quadrants, make it impossible 

 to traverse the arm and engage 

 any gear while any other gear re- 

 mains " in." When the lever is in 

 the neutral position, motion can- 

 not be imparted to the driving 

 wheels (even if the engine be run- 

 ning and the clutch engaged), as 

 there is no gear connexion between 

 A and C. 



Principle of Epicyclic Gears 

 Epicyclic gears are used on a few 

 types of car, of which the Ford 

 is a leading example. In the 

 epicyclic gear shown in Fig. 5, A is 

 the power or engine shaft, B pinion 

 secured on A and engaging with 

 pinion C formed integral with pin- 

 ions D and E, F is the epicyclic 

 axle, G the propeller or driving- 



Fig. 4. Diagram of four-speed gear box 



