THE AUTOMOBILE 



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carriage. At the end of this axle the wheel is mounted on 

 a short axle pivoted in such a way that it can be moved, so 

 as to turn the vehicle in any desired direction. The spindles 

 carrying the wheels are connected by a tie bar, so that both 

 front wheels move together. The motion of these wheels is 

 controlled by a steering wheel, whose motion turns a lever 

 connected with the spindle on which the wheel revolves. 

 (See figure 100.) The rear axle not only helps support the 

 weight of the car, but it is here that the power of the engine 



Wheel 'Spind/i 



Tie Bar 



Sfeer/ng Arm 

 FIG. 100. Front axle and steering mechanism. 



(See 



is transmitted to the axle so as to move the car. 

 figure 101.) 



Wheels and tires. The spokes of the wheel are made either 

 of wood or wire. On large motor vehicles used for carrying 

 heavy loads, solid rubber tires are frequently used ; but for 

 the ordinary car, pneumatic tires are used. These consist 

 of a tough outer casing which comes in contact with the 

 road, and inside of this and protected by it from wear is a 

 tube of rubber which is air tight. This is filled with air 

 under pressure by means of an air pump. In order to pre- 



