How Do Palm Couplings Transmit Torque?

Palm couplings, also known as flexible or jaw couplings, are mechanical devices used to transmit torque between two rotating shafts while accommodating misalignment and reducing shock loads. These couplings consist of two hubs, one on each shaft, and an elastomeric element, often called a spider, which connects the hubs. The elastomeric element is usually made of materials like rubber or polyurethane and is shaped like a spider, with multiple arms or legs that connect the two hubs.
Here's how palm couplings transmit torque:
Connection of Hubs: The two hubs are attached to the ends of the shafts that need to be coupled. These hubs typically have inward-facing jaws or fingers that engage with the arms of the elastomeric element.
Elastomeric Element: The elastomeric element, often made of a flexible material, is placed between the two hubs. The arms of the elastomeric element fit into the recesses or slots in the hubs. The elastomeric element is slightly compressed when the hubs are brought together.
Torque Transmission: When one shaft rotates, it imparts torque to the hub connected to it. This torque is then transmitted through the elastomeric element to the other hub and, subsequently, the other shaft. The elastomeric material deforms slightly under the applied torque, allowing the transmission of torque while accommodating minor misalignments and angular offsets between the two shafts.
The elastomeric element acts as a flexible link between the hubs, allowing for a certain degree of radial and angular misalignment and axial movement. This flexibility helps to reduce vibration, shock loads, and noise in the system, as well as protect the connected equipment from damage due to misalignment.
It's important to note that palm couplings are designed to handle moderate torque loads and are typically used in applications where precise alignment is not critical but flexibility and shock absorption are essential. They are commonly found in various industrial machinery, such as pumps, compressors, and conveyors, where they help protect the equipment from the harmful effects of misalignment and torque variations.