I wonder if anything will come of this Round table Discussion at the Hational Fluid Power Assocaition meeting in 8/07

http://www.nfpa.com/Pdf/Roundtable_Notes.pdf

Looked like some good points were made by the attendees.

I have done training myself.

I think in a lot of training classes there is too much time spent talking about individual components

Ground work needs to be laid about hydraulic principles. If your not careful in how you present this it starts to look like an engineering course and you lose the group that your training. It works well, however, if you constantly bring into the discussion actual components that the group uses. They can then see how the principle applies. Once they understand the principle, component discussion makes a lot more sense.

Example1:
Given a fixed hole size - more flow = more PSI differential. Then you introduce a flow control and look at charts and structure. At this point your not stressing the flow control but the principle.

Example2:
Function of a spring - force to compress a spring must increase as the spring compresses(spring rate). Introduce a simple check valve. Reinforce Ex 1 and explain that to make the hole bigger you must compress the spring further so the pressure against the dart or ball must increase. Now when you talk about the differentional pressure required to fully shift a pilot operated directional the spring is understood. When you talk about the increase in PSI needed to take a var. vol. pump from 100% to 0% flow the increase in PSI is understood because the function of a spring is understood.

Example3:
Pressure drops across holes cause heat. Pressure drops that result in work do not cause heat. Introduce a directional valve and cylinder.

Bottom Line:
If the principles are understood the student will be a better designer, troubleshooter, maintenance person, etc.
The instructor will not be successful unless the student sees the need to understand the principles.

As I saw Peter stated earlier, it is very difficult or impossible to put a value on every variable but if the student understands the principles, the unknown effect from the unknown variables can be minimized but, mostly, accounted for.

Jim K:

Take a look at the Ebook I use to teach Fluid Power basics at this address:

http://www.hydraulicspneumatics.com/200/eBooks/

There is also one I use to teach a Circuit Design class there that is partially posted.

I have a third book on Trouble Shooting Industrial Hydraulics that uses a different approach than most I've tried to use.