For anyone with an interest in Mechanical Engineering it’s impossible not to be hugely impressed by the feat of engineering that is the Britannia Class mainline locomotive “Oliver Cromwell” – one of the last four steam locomotives used by British Rail.

Aside from simple appreciation of this enormous machine (pictured above), I am bringing the Oliver Cromwell to your attention because Norbar recently donated 2 torque wrenches to the Great Central Railway (GCR) after being approached by one of the directors and Chairman of Cromwell Tools, Michael Gregory. Mr Gregory asked us if we could donate the wrenches for the maintenance of the steam locomotive engines and some of the GCR Diesel engines.

So, earlier in the month, I went up to Loughborough to present one Model 200 and one 5R torque wrench to Tom Tighe and Bill Ford (Managing Director, Great Central Railways Plc). Both wrenches will be used to torque cylinder bolts on the steam engines and also on the larger diesel engines that boast up to 2,500 horse power.

The Great Central Railway (GCR) is a heritage railway in Leicestershire, named after the company that originally built this stretch of railway, and is currently Britain’s only double track mainline heritage railway, with 5.25 miles (8.45 km) of working double track, period signalling, locomotives and rolling stock. It runs for 8.25 miles (13.28 km) in total from the large market town of Loughborough to a new terminus just north of Leicester.

Seeing as torque engineering became prominent at a similar time to the peak of locomotive engineering, it’s fitting that we were able to support the history and heritage of GCR and help keep their biggest assets on track and accurately torqued.

Philip Brodey, Sales and Marketing Director, Norbar Torque Tools

Like most drivers I often take my car into a franchised dealership or an independent garage for a change of tyres.

Usually, the mechanic removes and then replaces the wheel with a torque wrench.  All generally goes well until the first click of the wrench which signifies that the nut has been tightened to its optimum torque.

However, all too often in my experience the mechanic continues to tighten the nut beyond its optimum torque.  In the past, I have counted two, three and even four clicks of the torque wrench before the operator stops tightening.

The assumption appears to be that a nut can never be “too tight”.  Unfortunately, this is untrue, as the impact of a nut being too tight is as serious as being too loose.

For this reason, all car manufacturers specify the correct torque for wheel nuts on their vehicles in the handbook.  For example, a wheel nut on a BMW 5 series is 120 N.m, whilst a Ford Focus Titanium requires only 95 N.m.

Why is this important?  Because, when the nuts are attached to the wheel bolts or studs, the bolts stretch as the nut is tightened.  By over-clicking you apply extra torque and apply extra load which further stretches the bolt above and beyond its optimum capacity.  This brings the bolt closer to its yield point which can ultimately lead to bolt failure.

Conversely, under-tightening can be equally as dangerous.  A wheel nut applied with inadequate torque can work itself loose through general use or vibration of the vehicle.

So how can we define best practise when it comes to tightening wheel nuts?  First off garage operators must check the torque required by different vehicles.  The variation may only be minimal, but it is still vital to check.

Secondly, it is crucial to use a torque wrench checker or a torque wrench calibration device to check the accuracy of the wrench.  Our recommendation is that a torque wrench is checked at least once a year or every 5,000 cycles, which ever event happens first.  Busy garages can get through thousands of calibration cycles, or clicks, every month and it is important therefore to align torque wrench calibration with work volumes, to ensure the unit remains within accuracy.

Of course, torque wrenches are not the only method of tightening wheel nuts.  I’m sure many of us have been to garages where pneumatic impact guns are used to tighten bolts.  Again, there is a basic rule of thumb that must be followed.  If an impact gun is being used it must apply less than the specified torque and the task completed with a torque wrench in order to ensure accuracy.

All of this may sound overly complex but garages must remember that, in the event of bolt failure, if it can be proven that a bolt has been over-tightened, liability may potentially rest with them.

Dave Waters,  Norbar Torque Tools Ltd

One of the more frequently asked questions from our customers is “how do I select the correct torque wrench for application?”

Generally, most torque wrenches are used for tightening nuts and bolts accurately. Nuts and bolts need varying degrees of accuracy depending on the materials being fastened together, and therefore, there are different wrenches for different applications.

The two main reasons why we use torque wrenches are to achieve the correct level of tightness and then to ensure consistency across all of the bolts in the assembly. Used properly, a torque wrench will ensure that all bolts have the same level of torque applied. The effect of badly tightened bolts can be seen in lost time and money. It’s also worth noting that careless torque can cost lives.

The most common torque wrench is called a click wrench. This wrench is used to tighten bolts and nuts and will indicate when a pre-set torque has been reached. The pre-set value can be set by the user, or by a quality control department, but one thing that users must remember is that one click is enough. The first click the wrench makes signifies that the nut has been tightened to its optimum torque.

The second most common torque wrench is used to check an already tightened bolt to ensure consistency. The wrench can be equipped with mechanical or electronic sensing mechanism and also an electronic or analogue display.

There are of course other tools referred to as torque wrenches, such as hydraulic and pneumatic wrenches, powered by pressurised oil or air respectively. Both these tools are alternatives to impact wrenches and are much easier to operate, making less noise and applying torque with high accuracy and little effort. These devices are more likely to be used for larger applications such as flange bolting or when there are a large number of bolts to be tightened on an assembly.

There are other more complicated applications so do take a look at our product pages and if you need further information, get in touch.

By David Rollason, Marketing Manager, Norbar Torque Tools

Norbar’s portable USM-3 ultrasonic bolt meter measures the elongation and load in threaded fasteners, invaluable when the exact measure of fastener tension is essential for the integrity of a mechanical joint, such as applications in the aerospace industry or the Bloodhound SSC Project.

Correct torque settings have always been a feature of automotive design and maintenance – a topic well documented in some previous blogs . The industry has come a long way since the first Ford Model T’s. So much so that we are now manufacturing supersonic cars and striving to reach beyond the very limits of technology and engineering knowledge.

And it is this yearning for technological advancement in such an absorbing field that has led to Norbar joining the wide ranging list of specialist companies, educational and professional organisations, supplying products, services and expertise to the Bloodhound SSC (Super Sonic Car) project, which aims to push the world land speed record to an incredible 1,000mph. At a time of resurgent interest in UK engineering, Bloodhound is an exciting focus for British experience in this area and an inspiration for young people considering a career in this fascinating area of manufacturing and engineering.

As a Product Sponsor for the Bloodhound SSC project, we are supplying a range of torque wrenches, measurement equipment and our consultancy expertise in ultrasonic bolt testing. Setting accurate torque to fastenings on vehicles that are to be subjected to exceptional stresses induced by speeds well beyond the sound barrier, as you can imagine, is vitally important.

The 7.5 tonne Bloodhound SSC is jet and rocket propelled and capable of accelerating from 0-1,000 mph and back again to zero in just 100 seconds. Its jet and rocket engines generate a thrust of 47,000 lbs, the equivalent of 180 F1 cars. Pressures impacting on the vehicle include 30 tonne suspension loadings and air pressures of up to 10 tonnes per square metre.

Bloodhound SSC will be driven for this record breaking bid by the very brave Andy Green, who set the existing land speed record of 763 mph driving Thrust SCC in 1997. The new land speed record attempt will take place in 2013 in the Northern Cape desert region of South Africa, along a track 19km long by 500m wide, which required 10 million square metres of desert to be cleared by hand of rocks and other obstacles.

The Bloodhound project is a hugely ambitious and adventurous project which works as a great way to advance and promote technology. There are likely to be useful practical spin-offs as well as an increased public awareness about how engineering can be an enduring passion as well as a rewarding profession. Certainly something we at Norbar promote.

Philip Brodey, Sales and Marketing Director, Norbar Torque

In 1972 Leeds United won the FA Cup, 4 star petrol was 8p a litre, and Terry Harrison bought a Norbar torque wrench through Lewis Leathers Tool Shop in London. Now jump forward 40 years to 2012. Leeds now languish in the English Championship, 4 star petrol costs £1.40 a litre and Mr Harrison’s torque wrench is still in regular use.

Being an enthusiast, Terry had originally bought the wrench to assist with the reconstruction of Ford V6 engines; however, at the end of 1976 all of his tools were mothballed.

In 1984, Terry made a management buyout of the company Sherpa, which manufactured small, mainly hand powered forklift trucks (Stacker Trucks) and set it up as an independent company (Sherpa Stackers Ltd.).

The company fared well and one of the first actions was to install good quality tooling for machine building. It was to this end that Terry rediscovered his Norbar torque wrench after more than a decade. When he had it tested for accuracy it was still spot on!

As the company progressed so did the tooling and the Norbar wrench kept going. With each year that passed, Terry sent the wrench for testing and it returned from tests with a new certificate of calibration.

When the company itself was closed down Terry kept hold of his faithful old Norbar wrench and wrote to let us know:

“Having been used in so many situations, particularly for the construction of machines for the MoD, specifically the RAF, I am amazed that it has remained within tolerance, when tested at the Quality Control Labs each year. I still have the wrench and it is now used by my son in his business.

“What more can I say, this wrench has served me for virtually my entire engineering life, and it now serves my son. Your company obviously makes tools to last!”

We’ve been making torque wrenches now since 1942 so it’s fantastic to hear stories like Terry’s. If anyone else has Norbar equipment that rivals Terry’s 40 year old torque wrench then we’d be delighted to hear from them, but for now, here’s to Terry’s wrench making a half century!

By Philip Brodey, Sales and Marketing Director, Norbar Torque

This might well be the most frequently asked of all frequently asked questions and is rightly a subject of genuine concern to production and quality managers.

To answer the question, I am going to look to the standard BS EN ISO6789 – “Assembly tools for screws and nuts – Hand torque tools – Requirements and test methods for design conformance testing, quality conformance testing and recalibration procedure”.  Unsurprisingly, most of us refer to it as “the torque wrench standard”!

In 1992, ISO 6789 was very much a document covering the design and manufacture of torque tools and the requirement was that the tool should be tested at maximum capacity for 5000 cycles in each direction.  No guidance was given on recalibration intervals.

However, when the standard was revised to the 2003 edition, the scope was broadened to include “quality conformance testing and recalibration” and so became of relevance to people using torque wrenches rather than just those designing and manufacturing them.  This is the first time that the standard discussed the interval for recalibration.

For those looking for a simple answer to the question posed in the title, the default period of use between recalibrations is 5000 cycles or 12 months.  However, the standard recognises that many businesses will have their own procedures for the control of test devices and, as a torque wrench can be considered a test device, a company’s own procedures must take precedence over the default 5000 cycles/12 months.

The reason that there is really no simple answer to the recalibration interval question is that circumstances of use will vary widely and this will have a direct bearing on how long the torque wrench is likely to stay in calibration.  Factors such as the frequency of use, setting of the wrench as a percentage of full scale, general care taken in use and storage, ambient conditions in use and storage will all have their effect.  Another major consideration is the torque tolerance existing in every individual situation and degree of safety criticality of the bolted assembly.  For example, a helicopter assembly company that I have visited tests their wrenches before every single use.  A typical automotive garage might find this degree of control onerous and unnecessary.

The other important statement made by the standard is that if a torque wrench is subjected to an overload of 25% or more above the nominal maximum, it should then be recalibrated.  For many, this might be the ultimate decider on how often your wrenches should be recalibrated.  For some, it will be almost every time the wrench is used!

The draft version of the next release of ISO6789 is already in existence.  The good news is that in respect of the advice on recalibration, the standard has not changed.  When ISO6789 is published in early 2013 we will blog on the key changes that you should be aware of.

By Philip Brodey, Sales and Marketing Director

Anyone working in torque will have been taught to wind their torque wrench back to zero after every use.

Certainly, if the wrench is wound back at all it should not be adjusted below the minimum scale marking (usually 20% of maximum) – never to zero as this can adversely affect the calibration of the wrench. Beyond that, our position on this topic has been that it really depends on the application. We have thousands of Production Type wrenches in service that are left at their setting for months on end without a problem. Whilst the occasional user should adjust back to the minimum scale setting after use, if you use the wrench in an environment such as a commercial garage, the choice is yours. Either way is acceptable.

However, to test the position we have taken on the winding back question, we carried out tests over the past month. While we have not tested enough wrenches for this to be conclusive proof, the results provide some interesting insight into the debate. The test was designed to show the effects of leaving a torque wrench wound up at 100% of full scale against one wound down to 20% of full scale.

Firstly, four wrenches were taken from our production line and our calibration lab took results. Two wrenches were then left wound up to maximum and two wound down to their minimum scale setting. After 24 hours the calibration lab took further results, and again after a week, then again after one month.

The most significant result from the test is that all of the wrenches remained within tolerance, regardless of whether they were left at the minimum scale setting or at their maximum.  The wrenches left wound to maximum did move more but the change happened quickly, within 24 hours, and then they stabilised.

We acknowledge that we took a small sample and the result almost poses more questions than it answers.  For example, what happens to the same wrenches in 6 months and twelve months?  How does a Norbar wrench compare with our competitors in this regard?  These are tests that we will do and, no doubt, we will be returning to this subject.

For now, the test has not changed our view and our advice is this.  If it is convenient to wind your torque wrench back to its minimum scale setting then you should do so but never wind it below the minimum marking on the scale.  If winding back is inconvenient because you are using the wrench very frequently, then this will not damage your Norbar wrench.  Other factors in the way that torque wrenches are used and sometimes abused will have a far greater influence on calibration and the final torque delivered to the fastener than whether the wrench is left ‘wound up’.

If you want to continue the discussion further, don’t hesitate to comment below or tweet us here and join us on Facebook here, and we’ll talk torque!

By Philip Brodey, Sales and Marketing Director

So, the motorsport theme continues from our last blog. It’s hard not to address the topic of torque and motorsport every now and again when based in here as Banbury, together with Oxford and Silverstone make up the ‘Motor Sports Triangle,’ in the UK. Many F1 teams are based in the area.

There’s even a college campus specialising in motorsport; the Bicester campus, which sits right in the middle of the ‘Motorsports Triangle,’ and is part of the Oxford and Cherwell Valley College (one of four sites). The OCVC on the whole offers a huge number of apprenticeships and courses designed to really prepare students for the world of work. Already understanding the very important role that apprenticeships and practical experience play when it comes to preparing students for a career in manufacturing and engineering, we were more than happy to show our support to the college.

Reiss Pearmain, one of the students at the college, contacted us here at Norbar Banbury asking if we could support them with one of their projects. We duly provided torque wrenches to help them in their development of a gravity racer (soapbox car) which is due to compete in the Whitehill Bordon Soapbox Derby on the 4^th of June.

If unfamiliar with the concept of a gravity racer or soapbox car, it may be worth having a look at the video on this link or taking a look around the UK Gravity Sports UK website. The key to the race is gravity and using this force to race your car down to the bottom of the hill as quickly as possible.

Best of luck to the team (pictured above). We’re already looking forward to the race on the 4^th!

By David Rollason, Marketing Manager at Norbar Torque

It was only last month that I blogged about how vital the torque wrench was for simple bicycle manufacturing and generally how important torque was for those on two wheels. Well, today I’m going to touch upon the importance of torque for those who prefer four wheels to two.

It just so happens that one of those people who prefer four wheels, is our distributor in Norway. Frøde Lund of Verktøy AS Industri drives a rather special Austin-Healey which is pictured above (It’s a plastic bodied, 3000 MKIII 1964 model, 3 litre, 185 HP, triple 45 webbers for those of you who wish to know).

Recently, Frøde took the classic motor out on the famous Rallye Monte-Carlo Historique. Now, for those of you who aren’t familiar, no sooner is the Monte Carlo Rally done and dusted than it’s time for the Rallye Monte-Carlo Historique!

From Saturday 28^th January until Saturday 4^th February, competitors from all over Europe congregated in and around Monaco to test their driving skills on some of the most challenging routes anywhere in the world. But before that, of course, they have to get here – and that’s not always as simple as it sounds in a car which, according to the rules, must be manufactured between 1955 and 1980!

320 teams started off a day or two before the meet from a number of cities which helped to forge the reputation of the Rallye Monte-Carlo: Barcelona, Glasgow, Oslo, Reims, Turin and Warsaw.

Our friend Frøde started his journey in Oslo, driving 3,500km in what can only be described as adverse weather conditions. With major snowfall on the rally route it was no surprise that nearly a third of the cars that started didn’t make it to the end. However, Frøde and his Austin Healey did, and whilst they experienced some troubles along the way, there was no damage to the classic car, no claims and the team finished in a very respectable 124^th (they had been in 6^th after two days but the weather got the better of them over the subsequent three). The car itself was prepped with a Norbar Torque wrench.

When any machine is pushed to the outer limits of its capabilities every joint is put under immense stress. Frøde no doubt found peace of mind in knowing that accurate control was used on the car’s threaded fasteners.

To read more about motor racing and torque, read one of our previous blog posts here.

By Philip Brodey, Sales and Marketing Director

The importance of setting the correct torque when assembling equipment cannot be overemphasised. If you need an example of how important it is to set torque at precision accuracy, you actually need look no further than the common bicycle.

Old ‘bedstead’ bikes were generally easy and quite inexpensive to fix and an over torqued bolt might result in a stripped thread, simply requiring a trip down to the local bike shop or ironmonger.

However, those days are long gone and cheap and easy maintenance is a thing of the past because a revolution has taken place in the materials used in cycle manufacture. Heavy steel frames and components have been replaced by aluminium, carbon fibre, titanium and ultra-thin section steel tubing.

Bikes that are as light as those currently ridden in the Tour de France, such as one of Mark Cavendish’s specialised Venge  bikes, are now within reach of amateur racers and keen leisure cyclists – note the next cyclist you see when stopped at a set of traffic lights.

Today’s bikes have the required torque stamped on their critical components. Clamping down too hard on carbon bars will crack them but insufficient tension in the bolts may result in the bars moving in the clamp. A torque wrench is becoming an essential component in the cyclist’s maintenance kit! Long gone are the days of the Penny Farthing – the correct application of torque is vital to engineering performance when it comes to bicycles.

At Norbar we demand the same consistent levels of quality and accuracy when manufacturing a 200 Nּm Norbar torque wrench as we do in the production of more specialised equipment. All of our tools are designed and manufactured in house and supplied with traceable calibration certificates. Accuracy and traceability help us to ensure that internationally recognised standards of quality and reliability are maintained for equipment used worldwide and across every industry sector – whether on a deep sea pipeline or a Trek Madone 6 Series.

By Philip Brodey, Sales and Marketing Director