Pictured on the left is a main shaft used within a Proven 2.5kW Wind Turbine; there are two of these per machine. It is a single roll ball bearing located in a self aligning housing. On the right of the above image we have our Westwind 3kW main shaft bearing, which is a tapered roller bearing.

The table below shows a performance comparison of the bearings; information taken from NSK Bearings.

	Proven 2.5kW	Westwind 3kW
Radial Loads	Poor	Good
Axial Loads	Poor	Good
Combined Loads	Fair	Good
High Speeds	Excellent	Fair

• Radial Load - The force perpendicular to the axis of rotation, which in this case is the force being applied on the bearing from the end of the shaft.



• Axial Load - Also known as the thrust load, is the load applied to the bearing parallel with the bearing axis of rotation. In this case it is the load on the side of the bearing.



• Combined Loads - It is the combination of axial, radial and various forces acting upon the shaft & bearing.



• High Speeds - This evaluates the bearing when it is under high speed rotation.

Taking into consideration there is a lot of thrust on the end of the shaft due to the power being taken from the wind and that there should never be more axial load than the weight of the generator rotating parts it is clear that Westwind have designed a very robust product, having our bearing strength far superior than competitors. The high speed performance of the bearings is important; however it is not as crucial due to the machines being designed to be 'low-speed machines' i.e. The bearings should not be under very high speeds.

It would also seem the choice of the shaft / axle bearing on a Proven was made more on the suitability of the bearing being self aligning to suit the manufacture stage rather than the suitability of the intended purpose. The Westwind bearing however is more than suitable for the task expected of it; as we want to maintain a reputation as the most reliable product available.

Finally the issue regarding loading capabilities of the single row ball bearing versus te taper roller is another issue we consulted, and as you should also find; any bearing manufacturer will recommend the tapered bearing for having the superior size to strength ratio.

To conclude, our bearings used are more suitable not for their use alone, but as we use bearing that are overly strong for the task, their lifespan will be increased - as will the machine lifespan. They are the more expensive option, but nonetheless Westwind Wind Turbines will continue to provide our customers with the highest quality & most robust small wind turbine available.

In this image, on the left we have the main shaft bearing from a 6kW Proven machine, and on the right the main shaft / hub bearing from a 5.5kW Westwind machine. The NSK information on the bearings has no change (same performance indications as the previous bearings) and the same benefits of our bearings are still apparent.

This image displays the Bergey Excel 10kW single row 2rs bearing on the left and our Westwind 10kW tapered roller bearing on the right. The performance information is the same, were the tapered roller is the more suitable. We do not wish to offend Bergeys design, as their bearings are suitable for the job, however we just wish to show customers that our bearing used is used so that our robust machine will have a very long lifespan with minimal maintenance. If there was to be a fault in the bearing it is unlikely that it will collapse due to the oversized nature of the design - remember on each turbine there is two of these oversized bearing per machine.

Here is displayed the bearing on the left is the main input shaft / hub bearing from a 20kw Jacobs machine.
The bearing on the right is a hub bearing from a 20kw Westwind machine.
In this case Jacobs Wind Turbines have chosen a suitable bearing, however Westwind wanted to offer a much superior strength machine; and this can be seen due to the colossal size difference.

While we do not wish to imply any of the other manufacturer's bearings are not fit for the intended use; we are simply using this as an indication of the care Westwind Wind Turbines has taken in their choice of bearings for a long lifespan. We figure out what is needed and then exceed these requirements. It is our intention that we should never have a bearing failure as our bearings are under such a low level of stress.
There is a monetary cost element to this but we feel that our customers will appreciate our efforts to make a superior product. Every element of our turbines has had this attention to detail right from design to manufacture. The machines are heavyweight where it is needed but with no extra where it is not needed. The Westwind range does not "carry" any extra weight to absorb inherent vibrations. There are no untoward vibrations that need to be dampened.
Westwind in our 20+ year history have had minimal trouble due to fitting such oversized bearings and product components, however, if we use these oversized components then why are competitor turbines (of similar size) so heavy? In some cases the extra weight used to stop the machine vibrating and causing movement on the top of the pole, this concept does work; however Westwind prefer to take the engineering option and solve and vibration / movement problems rather than this option.

We have the experience. We have been the installers. We know all about 'parts only warranty'. We know all about endless repairs to machines while under warranty and the customer simply doesn't understand nor want to pay for the labor. J A Graham have been installing wind turbines since 1991. We were and will be for some time the largest small turbine installer in Ireland having installed several Megawatts.

As our history story explains, "We have tried the rest, now we have the best."