Early in the morning in the city rode the trolley. He held his long arms-rods for the wire, which is stretched over the street, and drove. Was in a hurry. See, afraid that people won't be late for him to work. Wanted, could even overtake the passing cars. But the trolley was stopped to plant some passengers to take other - and because of all lagged.
Suddenly, the roof of something rattling in the driver's cabin has filled up, and the trolley stopped in the middle of the road.
- Why not go? - alarmed passengers, glancing at the clock.
- Rod with wire jumped, " said the driver. "Nothing, citizens, do not worry, please, I quickly nalaga!
He opened the door, went outside, untied behind his car the rope, pulled it batted aside hand-bar trolley, again pressed it to the wire, took the wheel and drove on.
Before the trolley people on the streets drove large horse-drawn carriages, omnibuses ("omnibus" means "for all"). Then for omnibuses began to lay the rails. Turned out rly with horses - "Conca". Later, instead of a cart came up with the tram: under the car hid motors, above the rails pulled the wires, which gave power to the motor. Now the cars were driven not horses, and electricity. But the tram much noise, and the rails are expensive. Therefore invented the trolley. The trolley without rails, but the wires need anyway.
In fact, the power that moves the trolley, as well as the tram is electricity. Trolley receives electric current from the wires that are strung over the road. As current flows from the wire to the trolley using two hands - rods. The trolley must keep both hands"-rods for the wire. At least one wire will go - and do not move. In this he differs nothing from a table lamp. Her to Shine, we need to have two wires: if one breaks, the lamp will go out.