If you’ve ever taken to the sky aboard a Ferris wheel, maybe you’ve wondered just what keeps these marvels in motion. It might come as a surprise that much of the engineering behind the original Chicago Wheel (More on that HERE) is still at work in the its most modern of descendants, from the London Eye to The Wheel at ICON Park. This week’s Wheel Works will give you a nuts-and-bolts look into the design and mechanics that have kept these sky-scraping spinners rolling from the 1890s into the 21st Century.
You armchair architects building along with the #iconwheelworks challenge will definitely want to read on for tips on how to make your wheel strong with the force….s of nature (I couldn’t resist). Afterwards, we’ll put your new know-how to the test in the next phase of construction.
“Wheel” World Design
While the technology behind Ferris wheels has changed over the years, there’s one consideration that has always been at the heart of their design: gravity. You might have heard of it. From your experience… well, living on Earth…. you probably know that gravity is always pulling you toward the ground. The heavier something is, the harder it pulls. If you’re a multi-ton, solid metal wheel, that means just standing upright is a challenge, let alone moving at a constant speed all day!
To help distribute the pull of gravity, many Ferris wheels (including The Wheel at ICON Park) take their design from spider’s webs. Ferris wheels using a cobweb structure are actually two in one! The two wheels, equal in size, are attached at the outer rim by horizontal beams. The center of the wheel (called the hub) is connected by an array of spokes to a circular beam midway between the rim (called a crown). Crowns act as a sort of second hub that connect to the outer rim and helps continue rotation around the axle.
You may not realize it, but you probably have a cobweb wheel in your garage. Bicycle wheels work very similarly to Ferris wheels in that the lower half of the wheel supports the upper half through rotation. Of course, the wheels on your bike are probably made of light aluminum, whereas Ferris wheels are typically constructed out of steel or iron. These heavy metals have high tensile strength, which means they handle well under the immense pressure exerted by gravity. It also means that it takes a little more than pedal-power to turn these circular giants; however, maybe not as much as you’d expect.
Early Ferris wheels were powered by steam boilers, but today, the majority are completely electric. For instance, The Wheel at ICON Park is run on 14 electric motors that produce a combined output of 123 horsepower. That’s only about the same as an average automobile engine, making for a pretty energy efficient operation.
In addition to moving the wheel, motors are responsible for maintaining a constant speed of rotation. On the ascent, motors work to lift passengers against the pull of gravity. On the descent, they are challenged to keep the wheel from turning too fast with gravity and picking up too much momentum. The motors control speed and motion through a set of stationary wheels that rotate along the rim at the bottom of the wheel. The counter-spin causes the wheel to rotate around its axis.
In a traditional Ferris wheel, the axle is the true workhorse. It must sustain the full weight of the wheel, and keep it suspended above the ground. The axle is typically supported by two towers on either side of the wheel. On permanent wheels, these towers can be driven dozens of feet underground for support. Transportable Ferris wheels usually hinge towers to the wheel chassis and base for the needed stability.
So far, everything we’ve talked about concerns standing the wheel up straight and getting it to turn. But remember, these rotund revolvers must also carry people. Above the speed and structure of a Ferris wheel, it really is the cars, cabins, or capsules that really define the experience for rider.
On more traditional observation wheels, like your hometown wheel, capsules are equipped with a computerized self-levelling system that minimizes sway and automatically adjusts to the weigh distribution inside. Smaller wheels, usually more thrilling than scenic, are hinged with allowance for tilting and swinging. Another type of Ferris wheel, called an eccentric wheel, roll cars along a track built into the structure of a truss work creating a roller coaster-like ride. Of course, here at ICON Park, we like to take things nice and easy.
Whether built for rollicking exhilaration or high-flying relaxation, Ferris wheels are a testament to ingenuity and creativity in design. While meant to service fun seekers, they too provide inspiration to out-of-the-box thinkers that dare to be different. As monuments to humankind’s relationship with physics’ laws, these wheels of progress continue to roll us ahead into new ages of innovation.
Wheel Works at Home: Supporting Your Structure
Now that you know the science behind the design of Ferris wheels, it’s time to move onto the next phase of construction in your Ferris Wheel! Today, we’re going to assemble the supports (or towers) for your wheel’s axle. You’ll need:
- Popsicle Sticks
- Ruler/ Tape Measure
Step 12: Take two popsicle sticks and cut off on curved end on each. Glue the two cut ends together. Do this twice to give you two extra-long sticks equal in length.
Step 13: Lay the two ends of the extra-long sticks near each other while spreading the other end about 4 inches apart.
Step 14: Lay a popsicle stick across the extra-long sticks a half-inch down from the closest ends. Trim off the ends that extend past the extra-long sticks and glue it down.
Step 15: Lay another popsicle stick across the extra-long sticks about a half-inch down from the stick you glued in Step 14. Trim off the ends that extend past the extra-long sticks and glue it down.
Step 16: Glue one popsicle horizontally across the two extra-long sticks 2 inches up from the widest ends. Cut off the protruding ends of the glued stick.
Step 17: Take another popsicle stick and lay it diagonally between the horizontal sticks you glued in Step 15 and Step 16. Use a pencil to mark the part of the diagonal stick that overlap.
Step 18: Cut off the overlapping end of the diagonal stick and glue it into place.
Step 19: Lay another popsicle stick over the glued joint of the extra-long popsicle stick between the horizontal stick you glued in Step 15 and the diagonal stick you glued in Step 18. Use a pencil to mark the parts of the stick that overlap.
Step 20: Cut off the overlapping ends of the stick and glue it down.
Step 21: Lay another popsicle stick over the glued joint of the other extra-long popsicle stick between the horizontal stick you glued in Step 14 and the diagonal stick you glued in Step 18. Use a pencil to mark the parts of the stick that overlap.
Step 22: Cut off the overlapping ends of the stick and glue it down.
Step 23: After the glue has dried, turn the axle support over. Lay another popsicle diagonally over the diagonal stick you glued in Step 17, creating an “X” shape. When you have it in place, glue it down.
Step 24: Color your tower support!
Step 25: Repeat steps 12-23 until you have two identical towers.
Next week, we’ll put all the pieces together, construct your capsules and get your wheel in spinning order! Remember to share your progress on social media at #iconwheelworks! Stellar designs will be included in the final Wheel Works blog!
In celebration of ICON Park turning a big five-years-old this month, next week we’ll share the story on how the largest observation wheel on the east coast came to be. You won’t want to miss it!