Steve Spier / President / Norwolf Tool Works / www.norwolf.com
The Missing Link, a 4:1 torque multiplier, comes in half inch or three-quarter inch drive inputs. Several outputs range from 22 to 60 mm It weighs about 4 lb.
If turbines were standardized machines, a wind technician’s toolkit could be much lighter. But
that is not the case. There are dozens of turbine OEMs with dozens of models getting frequent updates and modifications. These make tooling challenges more common than some would like to admit.
Bolt-tensioning problems, however, are opportunities for new tools. Technicians (you) are talented and inventive people so that when confronted with bolting problems, it is not difficult to devise work-arounds, but sometimes not in the best way. For instance, machining an open-end wrench to fit a larger bolt is unwise because it may weaken the tool and that could be an accident waiting to happen. Custom made tools, such as those manufactured by our company, are one way to safely handle the variety of bolting challenges presented by the wind industry.
Take the Box Tower nut-torquing tool for instance. It was devised for the tight bolt pattern found in a particular 100-kW turbine. It provides a 2:1 reduction ratio so it operates at pressures up to 10,000 psi.
An alternative to the previous torque multiplier would be a bolt puller. These devices pull or tension a bolt enough to allow using a hand wrench to tighten a nut beneath the puller. This method is frequently used during construction on base tower bolts. A variation on conventional bolt pullers is a double acting, double stack device that also works with pressures up to 10,000 psi, an industry standard. The double acting version uses the same pump and hoses as the Box Tower.
Northwind 100-kW turbines use a tight pitch bolt pattern. The relatively narrow Box Tower, a 2:1 hydraulically driven torque multiplier, fits over bolts that are too close together for other tools.
The calibration tool Calibore comes in two different sizes and is used most for 36, 42, and 48mm tower bolts. The unit works to ±3% accuracy. Adaptors are available for the long tower bolts that OEMs seem to prefer. It can be used to certify most any torque multiplier, be it an air gun, electric gun, or hydraulic wrench used in the wind industry.
Another frequently encountered bolting challenge is working in a narrow space, such as adjusting generator feet and those on yaw pucks in wind turbines. A torquing tool called the Missing Link measures only 1.50-in. thick letting it fit into narrow spaces where high-ratio torque multipliers cannot. The relatively thin 4-lb unit provides a 4:1 ratio from a half-inch drive. Common applications are the 46-mm bolts on GE 1.5-MW turbines, and 24-mm bolts on Gamesa turbines. Yaw pucks use 60-mm bolts. This unit uses an adjacent bolt as a reaction point, as the photo on the previous page shows.
A big advantage over other devices that provide higher ratios is that this unit is lever driven while high-ratio multipliers are gear driven. So if one gear tooth is damaged, a high-ratio unit becomes unusable and must be repaired. Being lever-driven means that its teeth are always engaged and do not “roll” like gears. Thus, lever-driven unit can carry higher loads. Its design produced three patents.
Author Steve Spier
Lastly, to know that torquing tools working properly and accurately, it has been customary to send them to a lab for calibration and usually on a Skidmore machine. Hydraulic tools change as they are used, so depending on contractor, a crew could calibrate a hydraulic tool once a day or more in heavy use.
Another way to do so is on a device called a Calibore. The tool calibrator works on a built-in and patented reaction bar, and it’s one-third the weight of a Skidmore.
It works like this: Before a crew would tighten any bolts on a turbine, and to ensure they are using the right torque or pressure for whatever tool the crew is using, they would put a duplicate bolt in this device and torque it using the tool they intend to use on the job site. An engineering or construction spec would say, for example, apply so many kilos of tension to the bolt. Using a torque tool on the calibration device lets the device indicate a load on its gage that would come from the applied torque or pressure. It does not matter what torque tool the construction crew would be using. Then, to be sure the Calibores are accurate, we send our master calibrator to a lab at Columbia University, an independent third party, for certification. WPE
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