The RotaBolt monitored fastener operates within the elastic limit. When it is tightened, the RotaBolt indicator locks and the fastener load is then given by:

(Rota-initial set gap x E x A) /  (Length of Gauge Pin)

where E = Youngs Modulus of fastener

For any selected design load, the Rota gap is factory set against a machined bolt or stud surface with extreme accuracy so that when the Rota just locks, the correct load is achieved within an accuracy of +-5%.

Inserting the RotaBolt gauge pin does not reduce fastener strength, since the weakest point  of a fastener remains the threaded section. As shown in the photo elastic illustration opposite, the gauge pin is anchored in the uniform stress are in the shank of the fastener.

MATERIALS

Gauge pin - 12.9 carbon steel to BS 3692 : 1967
Rota-load indicator - stainless steel
Control cap - stainless steel
Anti -corrosion medium - Anhyrdrous high melt calcium base to grease to MIL-G 10924 and NATO G403

RotaBolts are available as standard in grades 8.8, 10.9 and 12.9 but can also be supplied in full range of specialized materials and surface coatings to customers' own specification. RotaBolt load monitored fasteners can be supplied complete or alternatively customers' own fasteners can be converted. The components can be supplied in compatible material to the parent fastener.

CORROSION RESISTANCE

RotaBolt components are protected by grease packed inside the closely fitting control cap. A high melt anhydrous calcium grease is used which gives excellent protection without affecting load indication.

IDENTIFICATION

Load setting is stamped on the caps.

PROOF LOADS FOR STEEL FASTENERS (Course Pitch) BS3692