2 Power Lock Manufacturers in 2023

What Is a Power Lock?

As the name suggests, a power lock is a device that locks (restrains) power (load force), and the name is a trademark of Tsubakimoto Chain Co. The device is a frictional fastening element that simply, strongly, and securely, fastens a shaft to a boss in a non-backlash condition.

Uses of Power Locks

Power locks are used as mechanical connection elements to connect the rotating shafts of various industrial machines with pulleys, gears, and other mechanical elements, because they are wear-type fastening devices. Powerlocks are mainly used in the fields of conveying, packaging, and printing machinery. The Power Locks are used for the final positioning of the power train, such as pulleys and sprockets, and its phase level can be adjusted with a single bolt and in the radial direction, thus contributing to space-saving design.

Principle of Power Locks

Power locks and other frictional load-locking devices are used in industrial machines, machine tools, semiconductor manufacturing devices, food processing machines, and other applications. There are two typical systems: wedge mechanical system based on the wedge principle and hydro-hydraulic system based on Pascal's principle. By understanding the advantages and disadvantages of each method and adopting a friction type power transmission fastening device that is suitable for the application and environment in which it is used, various advantages such as man-hour reduction and improved maintenance can be achieved.

The wedge mechanism method is inexpensive and versatile, but requires time and labor for installation and dismounting. Conversely, the hydro-hydraulic system is slightly more expensive than the wedge-mechanical system, but it is much easier to maintain, easier to install and remove, and quicker and more precise. This method is also compact, capable of transmitting high torque, has a large machining allowance, and can be used even when there are keyways, etc. However, because it uses many screws, removal can be time-consuming, and it is possible to forget to tighten them. On the other hand, the hydro-hydraulic system is easier to install and remove, has higher accuracy, and is superior to the mechanical system if cost is not a factor.

Tightening Torque of Power Locks

Power locks transmit torque by friction with the shaft, so if tightening is weak, the specified transmission torque will not be achieved.

To achieve the specified transmission torque, the tightening torque of the tightening bolt and the dimensional tolerance of the shaft must be controlled.

The tightening torque for bolts is listed in the manufacturer's technical data and ranges from 11.1 to 18.4 Nm for a shaft diameter of 20 mm, which varies from model to model. The transmission torque at this time is 61.7 to 62.7 Nm.

The recommended tolerance of the shaft dimensions is h6 for φ38 or smaller and h8 for φ40 or larger, and if the dimensions are too small, the transmission torque will be reduced. If the dimension is too large, mounting will not be possible.

Tighten the bolts diagonally and gradually, taking care to ensure uniform tightening. Finally, set the torque wrench to the specified torque and tighten all bolts. This prevents over-tightening.

Although multiple power locks can be installed on a single shaft, note that the transmitted torque is not simply proportional to the quantity. According to the manufacturer's data, the transmission torque is 1.55 times higher with two power locks and 1.85 times higher with three power locks.

How to Remove Power Locks

When removing power locks, loosen the pressurizing bolt to release the tightening by the wedge, but if the lock has been tightened for a long period, it may be stuck and cannot be removed simply by loosening the bolt. At this time, screw the bolt into the extraction tap next to the pressurized bolt hole and forcibly pull off the fastener.

Also, make sure that no load or torque is applied to the power locks during removal. The power locks may pop out or rotate during removal, resulting in a serious accident.

When storing the removed power locks, do not lose the attached bolts. The attached bolts are strong enough to satisfy the required tightening torque, so using bolts of other lower strength classifications may result in bolt breakage, etc.