Product category:
Bearings
News Release from: NSK UK | Subject: Super Precision ball bearings
Edited by the Engineeringtalk Editorial
Team on 23 October 2003
Bearings help cut friction in record
attempt
NSK has provided sponsorship and a set of specially adapted low friction, high-load bearings for the final drive system of E-motion, the UK's electric land speed record attempt car.
NSK has provided sponsorship and a set of specially adapted low friction, high-load bearings for the final drive system of E-motion, the UK's electric land speed record attempt car Having made a successful test run up to a controlled 169km/h on 15th July, E-motion is on target for the world record attempt in South Africa in May next year where the target is 483km/h (300mile/h)
This article was originally published on Engineeringtalk on 4 Jul 2008 at 8.00am (UK)
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NSK's micro-manipulation system features a three-axis (XYZ) positioning stage that facilitates the attachment of measuring devices, micromanipulators and microscopes for examining a preparation.
The bearings provide an essential link in the innovative transmission system; supporting both the car's weight and harnessing the final drive power to the rear axle.
The E-motion car accelerates relatively slowly up to 160km/h to overcome the initial inertia of a 1t rolling mass.
After this point the acceleration is much harder: "greater than that of high performance road car", according to team design and development director Colin Fallows.
"The efficiency of the drive system was a vital consideration in the building of this car, as every Newton-metre taken up by friction or transmission losses is robbing us of speed.
The bearings play an important role here, minimising rolling resistance to help ensure the final target speed is achievable", adds Fallows.
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The belt drive fitted to the car was deemed to be the most efficient method of transferring power from the motors to the axle and also provides a gearing stage, allowing the motors to work up to 6000rev/min, which according to the team's calculations, corresponds to 483km/h (300mile/h).
The other major consideration, the drag factor, was described as "the lowest of any vehicle" that had been through the testing facility.
All this effort to maximise the efficiency of the system is matched by the bearing solution, designed to withstand extremely high loads for a short space of time while providing the minimum of rolling resistance.
Two standard Super Precision ball bearings were chosen as the basis for the solution, the smaller contact area of the balls compared to rollers providing reduced friction and space within the cage for a nonpressurised oil lubrication system.
Providing a consistent level of lubrication was essential to maintain bearing life and to dissipate heat effectively, but had to be achieved without adding the extra weight of a pump and reservoir, or the initial stiffness of grease lubricated sealed type bearings.
The bearings are rated for over 10kh use in their normal application of a machine tool spindle, but the extreme loading on the back axle meant that the bearing life would be severely reduced but still more than adequate.
To achieve this, NSK engineers reached a compromise by balancing the weight, load, frictional losses and physical size of the space available to achieve the best solution for this purpose.
Mark Newby, the driver and co-owner of E-motion commented during the testing day: "NSK's support for this project has been fantastic, the NSK engineers remained flexible and inventive enough to bend the normal rules of bearing specification to achieve an ideal solution for our unusual requirements.
The company's sponsorship has also been in place from the beginning of the project, demonstrating their commitment to the environment and future technology; many of the lessons we have learnt about powering a vehicle electrically should prove useful to future designers of general-purpose electric vehicles.
We believe this development is essential for the future".
The current land speed record for a wheel driven electric car is held by a team in the USA at approximately 393km/h (244mile/h).
E-motion is designed to achieve 483km/h (300mile/h) within its normal operating envelope and could be capable of more.
To achieve the final target speed, the team require a longer running space than is available in the UK and so will be making a world record attempt on Monday 31st May 2004 at Verneuk Pan in South Africa, the location of Sir Malcolm Campbell's outright world land speed record attempt in 1929.
The team would welcome any additional funding for the trip and is actively looking for further sponsors.
Existing sponsors alongside NSK include Exide, which has provided the battery packs, and ABB, which has supplied the two 600V machine tool spindle motors and the inverter drive used to power the car. Request a free brochure from NSK UK ...
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