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THE NORBAR EVOLUTION


In 1942, at the height of World War II, Bill Brodey was engaged in selling various tools and machines, including Joseph Sunnen honing machines used for honing engine cylinder bores. Torque wrenches were being imported and sold alongside the honing machines because it was known that uneven torque tightening of engine cylinder head bolts would distort the cylinder bore. Brodey and his friend


Ernest Thornitt applied to the UK Ministry of Supply for permission to manufacture torque wrenches in the UK. Torque wrenches were much in demand for the manufacture of Rolls-Royce Merlin aero engines and the UK Government was keen to manufacture in the UK wherever possible to reduce pressure on the Atlantic supply convoys. Consequently, permission was granted to The North Bar Tool Company (as Norbar was then known) to start manufacturing torque wrenches in North Bar Place, Banbury in the UK.


 The Rolls Royce Merlin aero engine, seen here as a working display at the Abingdon air show in 2014, was the 27 litre V12 powerplant of World War II aircraft and renowned for its use in the British Spitfire fighter


At the end of World War II


the market for the Merlin aero engine dried up, along with all of the tools used in its manufacture. The North Bar Tool Company switched its attention to the manufacture of simple household goods like tables and trays. But as industry recovered, North Bar Tools went back its roots in the aerospace industry, manufacturing a range of specialist fitting tools, along with torque wrenches. Prior to launching the


Slimline in 1963, designed by Dr Henry Edward Merritt,


arguably Britain’s best known gearbox designer of the 1950s, all Norbar torque wrenches used an external, break-back mechanism. The Slimline was the first Norbar design to completely contain the mechanism within the body tube of the wrench, hence the “slim” reference. Some models remain in production today and variations of this mechanism underpin most of Norbar’s current torque wrenches. Norbar has manufactured


torque testers for almost as long as they have manufactured wrenches. The


FROM AIRCRAFT PROPELLERS TO WIND TURBINE BLADES


Norbar Torque Tools has launched EvoTorque2, building on themodel launched in 2014 and adding data capture technology. EvoTorque is designed to


deliver the correct torque output across both hard and soft joints. Safe to use on pre- tightened bolts as part of a verification process and, featuring a high tolerance of supply voltages and frequency variations, it specifically targets the wind energy market. EvoTorque2 can store up to


3,000 readings across 12 user IDs, all of which are time- and date-stamped. It willmemorise multiple targets, work IDs, user IDs and readings to ensure complete traceability and data availability. EvoTorque2 is factory-


calibrated to +/-3 per cent of reading and, thanks to the so- called “intelligent joint sensing”, it is able to continuallymeasure a joint during operation. If required, it will deploy dynamic braking to avoid over-shooting due to motor inertia. Where required, the


EvoTorque2 can take the user through a pre- determined tightening sequence and has three operationalmodes; torque, torque and angle and torque audit, the latter specifically designed for testing pre-tightened bolts. Usingminimal impact on the original fastening torque, it can


provide quality controlled data of joint performance over time. Sales andMarketing


Director Philip Brodey says: “On wind farms, during routine maintenance, it is common practice to check the bolts on turbines. However, when electricmultipliers are


triggered on bolts that have already been tightened, it can create a dangerous over- torque which in some instances can be as great as 100 per cent.Where this happens, there is an extreme danger that the application may fail due to overstressing the joint.” Furthermore, as there is no


 The EvoTorque2’s torque audit mode prevents over-


tightening when testing pre-tightened bolts –a feature that is particularly useful during routine maintenance where overstressing the joint


can lead to failure


need for final torqueing with a hydraulic wrench, EvoTorque saves users time on site. And because its output is not dependent onmotor temperature, its accuracy will not alter, enabling numerous joints to be tightened successfully. The range is available in


both 110V and 230V versions andmodels are capable of operating between 200 and 6,000Nm.


December 2016 /// Environmental Engineering /// 43


earliest types employed a simple spring balance attached to a pivoted bar. The next evolution was to utilise a hydraulic cell and hydraulically activated gauge. The Static Torque Meter was much more compact than the earlier versions and were easier to use because this system avoided the needle fluctuations of the spring balance type. This product enjoyed a near 50-year life span before finally being rendered obsolete by electronic measurement methods. The first reference to a


Norbar electronic torque analyser is dated 1967. The display, which incorporates an analogue gauge similar to a voltmeter, was attached by a cable to a separate strain gauged torque transducer. This essentially remains the method of measuring torque 45 years on, although the electronics are now based on single-board computer technology with such features as a colour display and touch-sensitive screen.


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