Machine Design

Clamp Nut from Hytorc Provides Secure Fastening for Critical Applications

The Hytorc fastener from Hytorc, a div. of Unex Corp. based in Mahwah, N. J. (, consists of a clamp nut, which includes an inner sleeve, outer sleeve, and a washer. The inside of the inner sleeve is hardened, and a washer prevents galling. The geometry of the nut lets the fastener apply mechanical tensioning to high loads, exerting bolt loads up to 1.5 million lb.

The clamp acts a mechanical tensioner and prevents bolts from being overstretched. It also eliminates highly stressed tension pullers. Technicians use a Hytorc driver and torque tool to move the outer sleeve clockwise, causing the inner sleeve to push up and rise with the bolt. This action exerts an accurate gentle cold stretch without residual load loss. The clamp exerts a pure tensile load, with no torque transmitted to the bolt. All components are in a managed force flow, so preload losses are negligible.

Installation is hands-free because there is no need for a reaction arm. The technician places the Hytorc tool on the fastener, even if it is inverted, stands back from the fastener, and activates the tool from a safe distance.

Sizes range from 1.5 to 7 in. in all thread forms, with low, standard, medium, and high-temperature ratings available.

© 2011 Penton Media, Inc.

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