Ferris Wheel

Background

A ferris wheel is an amusement park ride consisting of a large vertical wheel with places for people to sit or stand spaced evenly around the outer circumference. In operation, the ferris wheel revolves about a horizontal axis, and the riders are alternately lifted and then lowered as they are carried around the wheel in a circle. When the wheel stops, the people in the seat or platform at ground level exit the ride, and new riders take their place. The wheel then revolves a short distance until the next seat or platform is at ground level, allowing more people to exit and enter. This procedure is repeated until all the seats or platforms are filled with new riders, at which time the wheel is set in motion to undergo several complete revolutions. Although the name "ferris wheel" was not used until the 1890s, the wheel itself has been a part of human festivities for hundreds of years.

History

The earliest designs of wheels used for amusement rides may have been based on the large, circular wheels used to lift water for irrigation. In fact, knowing the human spirit, it is probable that adventuresome children used these water wheels for entertainment from the time they were first developed in about 200 B.C.

English traveler Peter Mundy described what he called a "pleasure wheel" with swings for seats after he visited a street fair in Turkey in 1620. In England, small handturned wheels were called "ups-and-downs" as early as 1728.

Whatever they were called, amusement wheels found their way to many parts of the world. One of the first wheels in the United States was built in 1848 by Antonio Maguino, who used it to draw crowds to his rural park and picnic grounds in Walton Spring, Georgia. As the concept of mixing amusement rides with park and picnic facilities caught on, several companies began manufacturing wheels of various designs. In 1870, Charles W.P. Dare of Brooklyn made several wood wheels of 20-and 30-ft (6.1-and 9.1-m) diameters, which he sold as the Dare Aerial Swing. The Conderman Brothers of Indiana made an even larger wheel when they developed a 35-ft (10.7-m) metal wheel in the 1880s.

The race for larger wheels culminated in early 1893 when American bridge builder and engineer, George Washington Gale Ferris, began building a 250-ft (76.2-m) wheel for the 1893 Colombian Exposition in Chicago. Designed like a bicycle wheel, with a stiff steel outer rim hung from the center axle by steel spokes under tension, the wheel could carry as many as 1,440 passengers at a time in 36 enclosed cars. The center axle was 33 in (84 cm) in diameter and 45.5 f (13.9 m) in length. It weighed 46.5 tons (42.2 metric tons) and was the largest steel forging ever produced at the time. The giant wheel opened on June 21, 1893, and drew more than 1.4 million paying customers during the 19 weeks it was in operation. The overwhelming success of Ferris' design ensured that his name would be forever linked with such wheels.

One of the people who rode the ferris wheel at the Colombian Exposition was American inventor and bridge builder William E. Sullivan. Sullivan was fascinated with the wheel and rode it many times. What was especially attractive to him was the possibility of making a smaller wheel that could be taken down and moved from one park or fairground to another. Drawing on his experience with bridges, he designed a 45-ft (13.7-m) transportable wheel with twelve three-passenger seats in 1900. In 1906 he formed the Eli Bridge Company and started manufacturing his wheel in Roodhouse, Illinois. Later he moved the company to Jacksonville, Illinois, where it remains in operation today. Most of the ferris wheels found in carnivals and fairs in the United States are made by the Eli Bridge Company.

Raw Materials

Because of the unique design of a ferris wheel, most of the component parts are fabricated by the manufacturer. Steel is the most common raw material and is used to make the trailer chassis, wheel support towers, wheel spokes, and wheel crossmembers. A variety of structural steel shapes are used depending on the application. They include square tubing, round tubing, angles, channels, and wide-flanged beams. Aluminum diamond tread plate is used for the entrance and exit walk-ways and for the operator's platform.

Aluminum is used to make the seats and the drive rims. The drive rims are rolled out of aluminum angle stock and are attached to the spokes to form a large circle about 10 ft (3 m) smaller in diameter than the outer rim of the wheel itself. Two rubber drive wheels press against the drive rims on each side to rotate the wheel. Aluminum is used in this application because the constant rubbing of the drive wheels quickly removes the paint on the rims, exposing the bare metal. If steel were used, it would rust.

The cushions used on the seats are molded from a self-skinning polyurethane foam. This material forms a solid, smooth skin on the outside, while the inside remains a compressible foam. Nylon is used for some of the bushings, and a phenolic plastic is used in some of the electrical components. Support cables within the wheel structure may have a plastic cover for appearance and protection from the elements. The electrical rings that carry electrical power from the hubs to the lights along the rotating spokes are made of copper, and the brushes that bring the power to the rings are made of carbon.

Some ferris wheel components are purchased from other manufacturers and are installed on the ferris wheel when it is built. These include the axles, brakes, tires, and wheels on the trailer. Other purchased components include the electric drive motors, the electrical wires and cables, and the electrical light bulbs and sockets.

Design

Ferris wheels that are designed to be transported on the road from one location to another must conform to the overall width, height, and length restrictions for highway vehicles. Although these restrictions vary from state to state, most states limit the trailer width to 8.5 ft (2.6 m), the height to 13.5 ft (4.1 m), and the length to 55 ft (16.8 m). No matter how big or small the ferris wheel is when it is opened and in operation, it must fold down to meet these restrictions when it is travelling on the highway.

The ferris wheel must also be designed to operate safely. This requires calculations to ensure the horizontal and vertical forces of the fully loaded wheel can be supported when the wheel is in operation. It also requires the design of safety interlocks to prevent the wheel from revolving during loading and unloading operations, and to prevent the operator from inadvertently operating the wheel in an unsafe manner.

The Manufacturing Process

The manufacturing processes used to make ferris wheels varies with the design of the wheel and the manufacturer. Most of the components are built in different parts of the shop before they are brought to the main construction area for final assembly. Here is a typical sequence of operations used to build a transportable ferris wheel used in carnivals and county fairs. In operation, the wheel described is about 60 ft (18.3 m) in diameter with a capacity to carry up to 48 riders in 16 seats.

Building the chassis

• 1 The trailer chassis forms the base for the ferris wheel, both when it is being transported on the highway and when it is in operation. The component parts of the chassis
  

  Raising a ferris wheel.
  are cut to length, either with a metal-cutting saw or with a torch, and are welded together. Two vertical support posts are welded to the forward section of the chassis. These posts hold the upper end of the two wheel support towers when they are in their lowered position for travelling.
• 2 The completed chassis is then sandblasted to remove any scale and spatter formed during the welding operation. This ensures a smooth surface appearance and prevents the scale from chipping off later and leaving patches of bare steel.
• 3 The chassis is then coated with a rust-in-hibiting primer. After the primer has dried, one or more coats of finish paint are applied in the desired color.

Installing the towers

• 4 The two wheel support towers are fabricated and painted elsewhere and are lifted into position on the chassis. The lower ends are attached to hinges on each side of the chassis, and the upper ends rest on the two support posts. The towers include ladders welded along one edge to provide access to the electrical rings and brushes at the wheel hubs and to the electrical drive motors and wheels that tum the drive rim on each side. The center axle is then installed between the wheel hubs at the tops of the two towers.
• 5 A long hydraulic cylinder is attached between the chassis and the wheel support tower on each side, about halfway along the length of the tower. These hydraulic cylinders are used to raise the towers into their upright position when the ferris wheel is being set up for operation. The cylinders are secured in place with a pivot pin at each end.
• 6 A separate lateral support arm is attached near the top of each wheel support tower. These arms each consist of two pieces of square tubing, with one piece slightly smaller in cross section so it slides inside the other. When the wheel support towers are raised for operation, the lateral support arms are pulled out to the side and the inner section of each is extended and locked in place with a pin. Two other pieces of square tubing are hinged to the chassis frame on each side and swing out to attach to the bases of the lateral supports. This gives the ferris wheel the required side-to-side stability it needs.
• 7 Hydraulic and electrical lines are routed inside the chassis frame pieces where they will be protected. The operator's control station is installed and connected. The chassis axles, brakes, tires, wheels, and stabilizer jacks may be installed at this time or they may be installed after all other work is complete.

Installing the spokes

• 8 Sixteen pairs of spokes run from the center hubs at the tops of the towers out to the seats. To install the spokes in the factory, the first pair of spokes is laid flat on the factory floor, and two crossmembers are installed between the spokes. One crossmember is located at the point where the drive rims will be attached, which is about 5 ft (1.5 m) in from the outer end of the spokes. A pair of curved sections of the drive rims are also bolted in place on each side at the same point. Only one end of the drive rim sections are bolted, leaving the other end free. This procedure is repeated for the remaining spokes, crossmembers, and drive rim sections until they form a stack. The inner ends of each pair of spokes are pinned
  

  A ferris wheel.
  to the pair below it. V-shaped lighting booms are installed between the center of every other outer crossmember as the stack is assembled. This overlapping pattern of lights produces a double-star effect.
• 9 The stack is then lifted onto the trailer with an overhead crane, and the top pair of spokes is pinned to the hubs. In operation, the spokes are all pulled into the vertical position when the towers are raised. The spokes are then pinned to the hubs, one pair at a time, and the free ends of the drive rim sections are swung down and bolted to the adjacent spokes to form the wheel—like a paper fan being unfolded.
• 10 Electrical cables are connected from the electrical rings at the wheel hubs to each lighting boom. Mechanical support cables are installed between the ends of the spokes around the outer circumference of the wheel. Other mechanical cables are installed in an x-pattern between each pair of spokes to give additional stability.

Finishing the wheel

• 11The entrance and exit stairs and walkways, safety fences, and trim pieces are fabricated, painted, and installed. The seats are fabricated and painted. In operation, four of the seats are carried attached to the wheel. The remaining seats are carried separately on the trailer and are manually lifted and pinned into place after the wheel is erected.

Safety Considerations

As with any amusement park ride, safety is the primary concern of both the manufacturer and the operator. Current safety regulations governing ferris wheels vary from city to city and state to state. The American Society for Testing and Materials (ASTM) is in the process of developing a comprehensive standard for the design, testing, manufacturing, and operation of all amusement park rides. Ferris wheel manufacturers and amusement park operators are actively participating in this process.

The Future

Having provided entertainment for several hundred years, if not several thousand years, the ferris wheel will probably continue to be a pleasurable experience for many years to come. Although roller coasters and other thrill rides may dominate amusement parks, the ferris wheel will still give riders the gentle thrill of being carried up in the air in an open seat to hang high above the crowds on a warm summer evening.