Superbolt mechanical multi-jackbolt tensioners (MJTs) are an innovative way to tighten large bolts safely and accurately with the use of simple hand tools. Actual tensioning is achieved by tightening the jackbolts that encircle the nut body. Superbolt tensioners are designed as a direct replacement for conventional nuts and bolts. There is low risk of galling, even in space-restricted areas.

Superbolt tensioners are designed as direct replacements for conventional nuts and bolts. These devices can be threaded onto a new or existing bolt, stud, threaded rod or shaft. The main thread serves to position the tensioner on the bolt or stud against the hardened washer and the loadbearing surface. Once it is positioned, actual tensioning of the bolt or stud is accomplished with simple hand tools by torquing the jackbolts which encircle the main thread. The jackbolts transfer the preload evenly into the main thread and, consequently, onto the joint. The main thread is tightened in pure tension.