As autumn peers around the corner, so too do the persistent bugs that bring many a healthy individual into a state of discomfort, accompanied by a red nose and an endless need for tissues. Surely after 40 plus years on this planet, having had a cold or two per year, we must eventually build a stronger immune system? Colds are a complete pain in the neck and I write this suffering from a cold that is adamantly loitering with intent to do grievous bodily harm. As can be expected, a cold will also choose to arrive at the least opportune moment, when the work load increases and there is just no time to take off.
I have to share that I learnt something new this week that really caught me by surprise. I do not often write about the technical side of hydraulics because there are far too many gurus out there whose knowledge exceeds mine tenfold, but this was interesting. The application required a completely normal four-port two-position spring return NG10 valve (P-A, B-T and P-B, A-T). In neutral with P-A there were no problems, when activating the solenoid with P-B there were no problems, however, when the solenoid was deactivated the valve stayed activated, even with the solenoid completely disconnected from the power source. It turns out, and was confirmed when reading the fine print of the catalogue, that a simple valve like this operates normally when there is flow in both directions. In this application the T port was blocked, therefore there was only flow in one direction. This uneven flow through the spool keeps the spool activated, over-powering the return spring action. SAFPA feedback is as follows:
Market survey
All companies that participated should, by the time that this copy of Motion Control goes to print, have their copies of the market survey posted to them. If you do not have your copy, please contact the SAFPA secretariat. They are also for sale from the secretariat to any other entity, either local or foreign, that would like a copy. All copies issued will be watermarked in an attempt to stop unauthorised distribution.
Technical meetings
So far we have had very interesting talks covering a variety of topics, which have all been well attended. Further topics in the pipeline for this year include load sensing; seals and O-rings; open and closed loop pumps; and welding and its technicalities. E-mail reminders will be sent to our distribution list or details can be found on our website.
Safety training course on hose assemblies
Now that we have preset dates and venues for this course they are starting to fill up. Please check our website for dates. This is a valuable course, especially in light of the ever more stringent SHE legislation.
Hydraulic handbook
We have finalised our SAFPA Hydraulic Handbook. This will also be forwarded to members in the near future and is available for purchase to the rest of industry. A useful document to have lying around your desk for reference purposes.
Regards
Norman Hall
| Tel: | +27 11 061 5000 |
| Fax: | 086 589 2158 |
| Email: | [email protected] |
| www: | www.vdw.co.za |
| Articles: | More information and articles about SA Fluid Power Association (SAFPA) |
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