Norbar gearboxes are built to an extremely high standard of precision. All gears rotate on needle roller bearings about hardened and ground journal pins. As a result, Norbar HandTorques can be relied upon to have a torque multiplication accuracy of +/-4%, throughout the operating range, taking the uncertainty out of high torque tightening.
No gearbox is 100% efficient and so the velocity ratio (the number of turns that the input has to make to achieve one revolution of the output) is not the same as the torque multiplication ratio. Norbar multipliers are engineered such that each gear stage has a velocity ratio of typically 5.45:1 which results in a true torque multiplication factor of 5:1.
Torque output calculations are therefore a matter of simple arithmetic with little risk of incorrect bolt loading due to conversion errors. Other manufacturer’s multipliers often require graphs or formulae to calculate the input torque to achieve a particular output.
The Norbar HandTorque is the most comprehensive multiplier range available. Standard products are available up to 47,500 N·m (35,000 lbf·ft) and ‘specials’ to 300,000 N·m (220,000 lbf·ft). A range of ‘nose extensions’ for reaching difficult to access bolts and full range of torque transducers for highly accurate torque monitoring are available.