Winch Wise – March 2016
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Project File:
High Roller – World’s Largest Ferris Wheel
Article:
The Beat of a Different Drum
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Wraps for What?
No matter what type of winch
you are operating (hand or power), ALWAYS keep at least the minimum recommended number of wraps of wire rope on the drum at all times. These will serve as anchor wraps ensuring that the wire rope will remain securely attached to the rope anchor. With an inadequate amount of anchor wraps, the rope could come loose causing the load to escape. The recommended number of anchor wraps may vary, based on applied design standards and the type of rope used. In many cases, 4 wraps are what are recommended. Direction of the rope spooling off the drum is important as well. In many cases, under winding is recommended in order for the winch brakes to operate properly.
PROJECT FILE: Mission Possible
Linq – Las Vegas High Roller Ferris Wheel
Las Vegas Linq “High Roller” Observation Wheel is currently the world’s largest Ferris wheel. The total height of the structure is 550 feet (168m).
The wheel structure consists of 7.2 million pounds of steel and 112 cables. Each 3″ diameter cable measures approximately 225 feet for a combined total of 25,256 feet. The High Roller features 28 spherical cabins that each hold 40 guests for a maximum capacity of 1,120 guests per every half-hour rotation. The cabins weigh approximately 44,000 pounds each and include 300 square feet of glass which provides a magnificent view of Las Vegas.
Besides providing a fantastic view of Vegas, the High-Roller is quite a spectacular view itself – Especially at night when it is beautifully lit with almost 2,000 fixtures.
The work, primarily performed by American Bridge, included the supply and erection of a 469′ diameter wheel that rests on a fixed spindle on four inclined steel legs approximately 283′ above ground level supported by a transverse braced leg: the hub, spindle, bearing, and cable spoke system; Thern supplied American Bridge with two TA5 Air winches to handle the task of pulling and positioning the one hundred twelve, 3″ diameter spoke cables. 
The winches have a maximum capacity of lifting or pulling up to 11,500 pounds. The High Roller also utilizes three Thern davit cranes for maintenance, one mounted on each side of the hub platforms and another down below. The cranes on either side of the hub are Thern’s Captain series cranes fitted with Thern power winches and are capable of lifting 2,200 pounds each. The cranes and winches are painted to match the Ferris wheel.
This was a very cool project that Thern is very proud to have been part of. The next time you are in Vegas, check it out and look for our cranes on the hub platforms.
The Beat of a Different Drum
Drums come in all different sizes, sometimes with multiple compartments, plain or grooved, with pressure bars, special cable anchors, drum locks and more. So, what kind of drum do I really need? First we have to consider the length of the pull or lift and the weight of the load – Which will determine the capacity of the winch, the diameter of the wire rope
needed to handle the load and how much wire rope will be needed to complete the pull or lift. Once we know how much rope the drum needs to hold, the optimum drum width and flange height can be determined for the application. Line speed requirements also play a very important role in determining the drum size. For instance, Thern’s winch that lowers the Times Square Ball on New Year’s Eve had to be very precise with line speed and the 130 foot distance required to lower the ball for the countdown to be perfect. The diameter of the drum, motor speed and gearing needed to lower the 12,000 lb. ball had to be precisely calculated in order to build the proper drum for the winch to complete the task in the exact time allotted. Should the drum be smooth or grooved? Does it need a pressure roller bar? Single or multiple compartments? How about an automatic level wind or manual line guide? And what about Fleet Angle…What the heck is that? We’ll cover more about drums in the next issue of Winch Wise.
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