Product category:
Drives, motors and power transmission, couplings, clutches
News Release from: SKF UK | Subject: Electro-mechanical actuators
Edited by the Manufacturingtalk Editorial
Team on 08 November 2005
Electro-mechanical actuators - a growing
market
Nick Brooker explains why the designers of modern forklift trucks are turning to electro-mechanical actuators, which, among other benefits, do not run the risk of oil leakage.
Since their invention, engineers have considered forklift trucks to be the domain of hydraulic actuators Until a few years ago, the same was true of plastic injection moulding machines
This article was originally published on Manufacturingtalk on 19 Apr 2004 at 8.00am (UK)
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Nick Brooker explains why the designers of modern forklift trucks and other applications are turning to electro-mechanical actuators, which, among other benefits, don't run the risk of oil leakage.
A forklift truck without hydraulics? No longer than five years ago, many designers would have laughed at such an idea.
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They would have come up with dozens of reasons why such a concept could not possibly be implemented.
The required power density in the lifting drive could not be achieved using any technology other than hydraulics - this would have been one of the first arguments.
The situation with injection moulding machines was similar up until about 20 years ago when leading manufacturers started presenting the first machines where electrical actuators replaced the hydraulic systems.
In the meantime the manufacturers of electro-mechanical actuators invested substantial effort in the development of their systems.
With more power, longer stroke lengths and higher speeds the range of applications has grown.
Today, actuators are available which are capable of forces from 5kN up to 10,000kN and strokes of up to 7000mm.
The operating speeds can reach 100 metres per minute, and duty cycles of 30 million double strokes can be achieved with designs using planetary roller screws.
Compared with hydraulic systems, electro-mechanical actuators offer numerous advantages apart from avoiding the aforementioned oil leaks.
For instance, they don't require complex and expensive peripheral systems.
In comparison, For the operation of just one hydraulic cylinder, an oil container, a hydraulic pump, a control unit, an oil filter, pipes and hoses, screwed connections and couplings and different valves are required.
Furthermore, electro-mechanical actuators can be easily controlled and are insensitive to changes in temperature.
Finally, when at a standstill, electro-mechanical actuators will remain in position, whereas many hydraulic designs must be fitted with an additional brake.
Apart from the mechanical considerations, electro-mechanical actuators are an attractive solution when it comes to the environment and avoiding contamination.
This is particularly important in applications in waterways (e g, actuators used in bridges or dam gates) or the food processing sector, where oil leakage for obvious reasons must be avoided at all costs.
In plastics injection moulding machines, electro-mechanical solutions reduce risk of fire from oil leaks in the high-temperature process.
Furthermore, more and more engineers in the automotive industry are recognizing the advantages oil-free actuation.
Here electrical actuators are replacing hydraulics in the drives for welding tongs, presses and forming equipment - not only because of their virtually maintenance-free operation and cleanliness, but also for their precision, robustness and ease of control.
So, it seems that the idea of a fork lift without hydraulics is not so funny anymore.
* About the author - Nick Brooker is with SKF Engineering Products, the Linear Motion Division of the SKF Group for the UK and Ireland. Request a free brochure from SKF UK ...
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