Big Wheel

In Beijing, China, plans are underway to build the Great Wheel of China, a giant ferris wheel that will hold the record as the world’s highest observation wheel, with views reaching the famous Great Wall of China.

The wheel’s manufacturer, Sigma, is using linear actuators to open the doors and electromagnetic clutches to control the yaw of each of the 48 observation carriages. These components are being provided by Warner Electric, part of power transmission group Altra Industrial Motion.

When the world’s tallest ferris wheel is completed in late 2009, it will stand 680 ft high (208 m), which is over 130 ft (40 m) taller than the current highest wheel, located in Singapore.

The wheel will have 48 air-conditioned carriages that will each be able to hold 40 passengers, giving it a total of capacity of 1,920 passengers. The wheel will be so high that on clear days passengers will have a view stretching all the way to the Great Wall of China.

The wheel is predicted to make 750,000 rotations over a period of 50 years, so only products that are designed to deliver extended service life were considered, according to the manufacturer.

Linear actuators for each of the 48 carriages will be used as a secondary lock to prevent the door from opening during rotation. The actuator was designed in accordance to customer specifications, which included an adjustable end limit switch, end stroke signalling, specific stud, nut and washer arrangements, a manual release lever and extruded aluminium tube bodies to avoid corrosion and reduce weight.

Warner Electric designs and manufactures a full line of maintenance-free linear actuators for applications ranging from light to rugged duty. Each actuator has an ingress protection rating of IP65, meaning they can be subjected to low-pressure jets of water from all directions. All products can be mixed and matched to accommodate custom orders quickly and effectively.

Each cabin of the Great Wheel of China has also been equipped with a Warner Electric electromagnetic tooth clutch to provide stability to the carriages. The clutches will prevent the carriages from swaying in the wind, which is necessary to prevent passengers from suffering from motion sickness throughout the 20-minute ride.

The clutches keep each carriage axis vertical as the wheel rotates. If the carriages were left to hang freely, they could sway too much for comfort in the strong winds that are present at such a height.

A tooth clutch provides higher torque in limited areas, which means that the relatively small clutches are able to stabilize the cabins, according to Pierre Lootvoet of Warner Electric. Each clutch has a flexible coupling that compensates for misalignments and allows for easy mounting. In the event of the transmission locking on the wheel, the clutch will be disengaged to leave the cabin free. A hand release lever also allows for manual disengagement.

For information on the clutches and actuators used in this application, visit www.altramotion.com.

Reader Service Card No. 422