Hi, this is Wayne again with a topic “Make Inventions: Otis Safety Elevator”.
Various kinds of lifts, hoists and elevators have been around for thousands of years, but they were generally considered too dangerous for people to ride a broken rope would mean a quick and violent death. They had such a bad reputation that when elijah otis invented his safety elevator, he found them difficult to sell. That is until 1854, when he built a four-story elevator at the new york world’s fair in front of a crowd of curious onlookers. He rode his elevators to the top and then commanded his assistant to cut the rope with an axe when the rope split, the elevator fell only a few inches and stopped. He repeated the demonstration every hour of the exhibition and survived to see a safety elevator business.
Take off otis reveals his simple but reliable idea in his patent application, but is difficult to make out even zoomed in i’ll build a scale model to illustrate better a simple elevator rides rails up and down and is held aloft by a simple cable. If the cable breaks the elevator drops otis’s elevator and a mechanism between the cable and the elevator car, when there is tension on the cable, the levers retract allowing the car to move freely. But when the cable breaks, the tension is released and a spring pushes the levers engaging the pawls along the rails, holding it securely, i don’t have room for a full scale. Elevator, but building a half scale model should be big enough for me to take it.
For a ride, the basic frame of the elevator car is built from plywood and two by fours, when the elevator is running. Normally, it’s supported by the mechanism that operates the levers. A steel plate helps reinforce the frame and i use a leftover piece of steel pipe to operate. The levers eye bolts, connect it to the pulleys that lift the car.
The levers that stop the car in case of a broken rope are made from square steel tubing. Each lever has a spring: that’s guided and held in place by a pivoting pipe when the rope is under tension, the levers retract, but when it’s released the springs, push the levers into place. The levers don’t do anything without a rester hooks in case of an accident. They’Ll need to stop the entire weight of the car, so i build them from sturdy. Strap hinges bolted to the side of the car. Tabs are welded to the back of the hinge to attach a turnbuckle that connects to the lever. The turnbuckle makes it easy to adjust how far the hooks deploy. Finally, i heat up the end of the hinges and bend hooks, so they can actually catch something for the short length of track that i’m building.
I make a sandwich from two by fours and two by twos. I use links of steel rebar as the cross pieces for arrester hooks to catch on. I make the track square straight and sturdy by reinforcing it with angled support beams. Finally, i add rolling guides to keep the car aligned with the arresting track.
I make sure everything is comfortably reinforced and tighten all the bolts. Then i run some tests before. I trust myself to it with a dozen successful tests. It’S time to test it myself, i don’t have an assistant and good rope is expensive, so i pull myself up and release the rope when i’m ready to test the brakes. I was pretty confident i wouldn’t fall too far, but it was still pretty harrowing. Elijah otis safety, elevator changed the world skyscrapers became practical cities could grow upward as well as outward top floors, went from being the cheapest real estate to the most sought. After today, elevators safely transport billions of passengers every day, i’m steve hofer for may conventions. You .