The bearings support the weight of the bridge and each have to cope with around 80 tonnes in weight. The work to replace the bearings is expected to take around 20 weeks.

Bridge engineer at Derbyshire County Council Graham Hollet was quoted as saying on the BBC that these types of bearing only have a finite life, he said:

“The bearings are nearly 30 years old,

“They are deteriorating and not allowing the bridge to move as it was designed to.

“If we leave them unchecked, it would set up unacceptable stresses on that bridge which would lead to very expensive repairs and would put the structure at risk.”

There are around 100 bearings in total on the bridge, all of which will need to be replaced. In the meantime temporary structures will be built to support the weight of the bridge so effective bearing replacement can be carried out.

A mock hospital has been built on a ‘shake-table’ at a test site so engineers can induce earthquake-like shaking conditions.
If positive, the tests will confirm whether the rubber bearings are able to support the degree of movement which might be expected if an earthquake were to occur. Rubber bearings are frequently used in Japan in similar constructions.

It is the first time that this new type of bearing system has been tested in the US to such a scale and it’s hopeful the results will prove positive.

Engineering Professor Tara Hutchinson said:

“What the bearings do is uncouple the building from the motion of the ground during an earthquake, like putting the building on roller skates,

“What we found is that the contents of the building carried on working after our ‘earthquakes,

“If the equipment had been life-support systems keeping real people alive, then the bearings would have saved their lives.”

Comparison tests are now being conducted to see what damage would have been sustained had the rubber bearings not been used.

At HillHead 2012, SKF, the popular bearing manufacturer, are planning show their range of innovative new bearing products, among them is the SKF Explorer self-aligning roller bearing.

The Explorer range of bearings has been expanded immensely and now features upgraded component design, improved manufacturing processes and a wider range of bearings suitable for many more applications. The new designs help the bearings to resist the heavy contamination present in the quarrying, mining and construction industries.

Other bearing products being showcased by SKF include their new SE bearing housing and SKF idler sound monitor.

The new idler sound monitor from SKF is an easy-to-use handheld device which can detect faults in conveyor belt idlers. The device uses acoustic enveloping technology, which can distinguish between those sounds generated by a good idler and those sounds generated by a faulty idler, enabling easy condition monitoring in tough working conditions.

Tapered roller bearings are used in car wheels because they can support the weight of the car whilst are also able to support the cornering forces generated by great axial loading.

In tapered roller bearings the rollers are set at an angle between the raceways. This means that the apex of the tapered rollers will intersect at a point on the bearing centreline, depending on the type of bearing and the load which needs to be supported. Tapered bearings are usually used in pairs so can cope with the induced force in either axial direction.

Needle tapered roller bearings feature needles instead of rollers which are usually around three to ten times longer than their diameter. These can support high loading whilst also offer high rigidity for applications in which require smaller than normal bearing sizes.

Bearings need to be maintained properly to ensure they remain in a good working condition for as long as possible. And this means that they need to be lubricated at regular intervals.

Incompatible lubrication can have disastrous consequences for a bearing. If two different types of lubrication are mixed together three things can happy. If you are lucky there will be no direct consequence but… If you are unlucky, the mixture will harden and the lubricating oil will not be released meaning bearing failure, or the mixture will soften and the mixture will be too thin to lubricate the surfaces sufficiently and the bearing will fail.

If you need to re-lubricate a bearing and you don’t know the type of grease that was previously used, it is always better to remove the old grease from the bearing completely before you add new grease. This will ensure that the bearing will not fail due to the use of an incompatible substance and future lubrication of the bearing can be done knowing the type of lubricant used.

Even in rotating systems, which are manufactured to the highest tolerance levels, there will always be wear. But using the right lubricant can reduce this wear significantly.

Any lubrication which you add to a rotating part or component will reduce wear on the component surfaces but the lubrication can also do other things besides. Lubrication can reduce the heat created by friction and hence can mean that parts can rotate faster without temperature increasing markedly. If a bearing, for example, is allowed to increase in temperature the molecular structure of the metals can be altered and component size can increase.

As well as removing the heat from a bearing, the lubricant applied to the bearing can also stop the bearing corroding and stop moisture entering the rotating parts. The lubricant or grease also stops dirt, debris and other grime entering the bearing and so protects the bearing from being damaged by these foreign bodies.

If you have bearings on a machine you may well have a schedule of work which enables you to check the bearings on a regular basis. Things which a maintenance engineer might have to do include:

• Check bearings for unusual noises whilst the machine is in operation
• Check shafts or housings to which bearings are mounted run true
• Lubricate certain bearings on a weekly or monthly schedule
• Clean areas around bearings to avoid contamination
• Check running temperatures of bearings
• Check bearings whilst the machine is at standstill for tight spots or roughness
• Change bearings when they have completed their estimated service life or maximum number of rotations

If a maintenance schedule is followed bearing life will be extended and downtime will be reduced.

Every industrial company receives goods on a frequent basis throughout the week, and in many cases these goods are sat on pallets due to the quantity received and their weight. Pallet trucks are thus then the easy way to move these goods from one location to another. The truck is simply slid under the pallet, the hydraulic pump action lift is raised and the goods can then be pulled to their required location.

Pallet trucks receive a great deal of wear and tear over the course of their lives and are usually neglected until they break down.

The first part which usually causes problems on a pallet truck is the rollers. Pallet truck rollers do wear out over time but they can be replaced with new rollers quite easily by your maintenance staff.

If you take a look at your existing roller on the truck it will usually contain a code which can be used to reference a replacement part. Some rollers have integral bearings whereas some rollers require fitting on the bearings already located on the roller housing of the pallet truck.

One of the biggest problems any drive will face is sheave wear. The sheaves are permanently in contact with the belt and after time the faces of the sheave and also the bottom of the sheave can become worn.

If you are replacing a belt on a drive you need to check the sheaves before the belt is fitted.
Things to check include:

• Make sure the sheave faces aren’t shiny – this can cause belt slip
• Check the faces aren’t dished out – this will cause rapid belt wear
• A belt should ride in the grove of the sheave so that it is just higher than the sheave top – if this doesn’t happen then check the belt is not riding on the bottom of the sheave and the sheave bottom is not worn
• Make sure there are no burrs on the sheave and file any smooth if necessary

One of the most popular types of inverter available is manufactured by Lenze. Lenze drives are popular because they are easy to install, easy to maintain and they can be worked on easily by maintenance personnel.

Lenze inverters can be powered by a single phase or three phase supply and have an easy to program user-interface. Some drives also come with a removable parameter chip, which can be programmed offline and then inserted into the drive so the drive can be used straight away. This is especially beneficial for maintenance staff, as if the drive fails it can be replaced quite quickly without any manual programming of parameters reducing machine downtime.