CLAMPING DOWN
Clamp-style collar

Clamp-style shaft collars are a simple design with easy installation. They are used as mechanical stops, locating components and bearing faces. They come in a one or two-piece design, both using socket head cap screws. With Set Screw type collars, the set screw protrudes into the shaft, but the clamp-style collar screws act to compress the collar and lock it into place around the shaft. They work well on practically any shaft. The design is easy to use and keeps the shaft from being damaged. It also creates a holding power that is nearly twice that of a set screw collar.
Two-piece clamp styles can be disassembled and installed in position without being slid over the shaft or removing any components. It also provides the most holding power of all the shaft collars.
Clamp-style collars have been around since World War II. They were used in bombsights and guiding systems.
No one knows who invented the clamp-style collar.

Information gathered from Wilipedia and William Hewitson, Director of Mfg and Engineering, Ruland Mfg Co., Inc. www.ruland.com