Children's Encyclopedia1976 |
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Pàgina 54
... wheels of vehicles was not new . The Ancient Greeks cut smooth grooves in their roads for the wheels of chariots . Much later , iron tracks were used in coal mines to make the ladened wagons move more easily . But with the inven- tion ...
... wheels of vehicles was not new . The Ancient Greeks cut smooth grooves in their roads for the wheels of chariots . Much later , iron tracks were used in coal mines to make the ladened wagons move more easily . But with the inven- tion ...
Pàgina 56
... wheels . The emergency brake acts only on the back wheels . It is used to keep the car from rolling when it is stopped . The Valves Holes called valves at the top of the cylinders must open and close at just the right moment . These ...
... wheels . The emergency brake acts only on the back wheels . It is used to keep the car from rolling when it is stopped . The Valves Holes called valves at the top of the cylinders must open and close at just the right moment . These ...
Pàgina 57
... wheels with teeth are gear wheels . The small wheel has 9 teeth , the big wheel 18. If the small wheel is driving the big wheel , the big wheel will turn at only half the speed of the small one . Turning the Wheels Some cars have ...
... wheels with teeth are gear wheels . The small wheel has 9 teeth , the big wheel 18. If the small wheel is driving the big wheel , the big wheel will turn at only half the speed of the small one . Turning the Wheels Some cars have ...
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