The Hidden Grip That Pulls a Cable Car

Some streets in San Francisco, California, rise like long ramps. Getting a heavy cable car up such a steep hill takes a strong pull. Yet the car carries no motor to pull it uphill. A photo guide with the heading “A Pull from Below” helps explain this surprising ride.

The first photograph shows a cable car on a hill. Two rails support its wheels. Between the rails, a narrow slot runs along the street. The caption says, “The opening leads to equipment below the road.” The photograph shows where to look, but the pulling cable is hidden underneath.

Below the street, a thick steel cable travels through a channel, or narrow passage. While the system is running, the cable moves at a steady speed. The cable car needs a way to catch this moving cable and be pulled along.

The second photograph shows a museum display with the street covering removed. A metal tool reaches down from beneath a cable car toward a cable. The caption identifies the tool as a grip. Its two jaws are parts that can squeeze together, somewhat like the ends of kitchen tongs.

The person operating the car uses a lever to close the grip around the moving cable. Once the grip holds firmly, the cable pulls the car along the rails, including uphill. The display photograph makes the grip easy to see, but its cable is not moving.

Where does the cable get its motion? The third photograph shows large wheels and thick cables inside a building called a powerhouse. Its caption says, “Motors turn wheels that move the cables beneath the streets.” This machinery supplies the pull. The motor stays in the building instead of riding on the car.

To stop, the operator releases the grip and uses brakes. The cable keeps traveling while the car stays at the stop. Together, the photographs reveal different parts of one system: the street opening, the hidden grip, and the machinery that keeps the cable moving.