Taking torque around corners

Frequently in machine design, it is critical to transfer torque between points that are not perfectly aligned. This article addresses methods of getting couplings to join rotating drives when the alignment is off at angles over 10-degrees. For these situations, there are a few options: Cardan-type joints, flexible shafts, and block-and-pin joints. Cardan joints use rolling-element bearings to reduce friction. Cardan joints can be found in a variety of applications such as industrial drives, metal rolling-mills, and steering columns. They work best in high-speed, low-torque scenarios where the misalignment is less than 15-degrees. Flexible shafts have almost no limitation on misalignment. They can even be subject to multiple misalignments on the same shaft which allows for the transfer torque around multiple obstacles. The weakness with flexible shafts is that they are limited by the bend radius. A smaller shaft radius will result in less possible torque. Finally, block-and-pin joints are the most versatile of the joints and can be used for misalignments of 35 to 70 degrees. They can achieve very high torque but have problems maintaining a constant speed of rotation. They are used frequently in jets, convertible cars, and washing machines.  Full article at Machine Design.