The wind industry has spawned a range of equipment and tools for it use. Much of it centers around bolting and devices that make such tasks easier and safer. There is not much room to maneuver in a nacelle, so when bolt tightening is the task at hand a torque multiplier can be a better and safer alternative to a long wrench. A torque multiplier increases the torque that can be applied by hand. Of course, output power cannot exceed the input power, so the number of output turns will be fewer than the number of input turns. A brief equation shows how the mechanical parameters relate.
Power = torque x speed
Hand-torque multipliers use an epicyclic or planetary gear train with one or more stages. Each stage of gearing increases the torque applied by a factor of about five.
Electric torque wrenches are gaining acceptance in tower construction. One version of such a tool applies torque with ±3% accuracy and ±2% repeatability, and because it is electric it can store the value for the torque applied to each bolt in a file that can be downloaded later.
The gun uses an ac-servo, brushless motor coupled to a 490:1 gear multiplier to generate the high torque. It operates by measuring and controlling the current output of the ac-servo motor. This measurement and control allows for a good degree of accuracy and repeatability. An internal CPU stores a torque-versus current calibration curve so that when the motor reaches a required torque, identified by electrical current, the motor shuts off.
Filed Under: O&M
