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Fourth gear

Fourth gear

In fourth gear, the input shaft and mainshaft are locked together, providing 'direct drive': one revolution of the propellor shaft for each revolution of the crankshaft. There is no increase in torque.

Explained in

    How manual gearboxes work

    Internal-combustion engines run at high speeds, so a reduction in gearing is necessary to transmit power to the drive wheels, which turn much more slowly. Read more

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