Air, will your hydraulic equipment let you down in 2011?

Happy New Year Air,

If you're like me, you're probably starting to think about
what lies in store for you this year.

So here's a question for you:

Will your hydraulic equipment let you down in 2011?

Maybe. You see, just like all other mechanical equipment,
your hydraulics can give trouble at any time.
And when it does, you need the right expertise.

Problem is ...

Good help is hard to find.

But now YOU CAN have a hydraulics expert at your beck and call -
24 hours a day, 7 days a week, 365 days a year - and for peanuts.
His name is Peter Rohner. And he's a hydraulics engineer with
42 years of experience. Experience that can SAVE you a bundle.

Take, as an example, seal failure in hydraulic cylinders.
Do you know up to 25 percent of cylinder rod-seal failures
are caused by bent rods?

There are a few basic reasons why cylinder rods bend.
Peter Rohner shows you how to determine
the underlying cause and the ways to correct it
on pages 58 and 59 of his hydraulics book.

During his 26 years as a University lecturer, thousands of people
gained from Rohner's knowledge. And through his books on
hydraulics, pneumatics and PLCs, tens of thousands more
have profited from his expertise. You will too.

Now in its fourth edition and with 28,214 copies in print,
Rohner's hydraulics book is possibly THE most popular
hydraulics manual on the planet.

AND it's full of practical information every
hydraulic equipment owner ought to know ...
that most mechanics DON'T.

So make a New Years resolution
to appoint Peter Rohner as your hydraulics advisor
and get a copy of his hydraulics book today.

It could turn out to be the most valuable resolution you make.

http://www.hydraulicsupermarket.com/rohner.html

Yours for better hydraulics knowledge,

Brendan Casey

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Australia
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Air two very valuable pieces of paper

December 14, 2010  'Inside Hydraulics' Newsletter http://www.hydraulicsupermarket.com Issue 101 IN THIS ISSUE 1. Be your own Santa 2. What is a picture really worth? 3. Another piece of paper you shouldn't be without 4. Content for your web site or e-zine 5. Help us spread the word 6. Tell us what you think 1. Be your own Santa Last weekend I bumped into Santa at a shopping mall and was reminded of a Santa Claus story crafted by Glenn Turner, which I first came across a couple of years ago, and told by him much more elegantly than I will summarize here: A boy from a very poor family, who each year asks Santa for whatever his cousin (from a very well off family) asks for. One year a pony; the cousin gets a pony, the boy gets hand-me-down clothes. The next year thinking he is erring in his approach, the boy carefully copies his cousin's letter to Santa word for word, politely asking for a bicycle. His cousin gets a bike; the boy gets hand-me-down clothes. In response to this great disappointment the boy goes out behind the barn, with tear-filled eyes but with a rage-closed fist raised to the sky and says, "OK Santa, if that's the way you want to play it!" and then sets about being his own Santa Claus. This is of course a success parable and hopefully its meaning is obvious: far too many people childishly rely on others to give, to appoint, to authorize, to promote, to grant permission, to set their life's agenda for them. Comparatively few accept full and total responsibility to be their own Santa and grant their own requests. Fact is, there isn't any fat guy in a red suit coming down your chimney to bring you that new boat you've been lusting after, or that fat retirement account that'll guarantee your security. But acknowledgement of this grim reality is empowering - just like it was for the boy in the above story. So it's in this context that my wish for you in 2011 is that you 'write your own ticket', Air. Make no small plans, no big compromises. Set, pursue and achieve a lot of goals. Resist mediocrity and ignore less creative or ambitious peoples' criticisms or disapproval. And thank you for your continued support, interest and creation of value for yourself, your company and your family from my work here and elsewhere. I am motivated by it and appreciative of it. Happy holidays! The Nice Things People Say ... "The knowledge I've gained from this information has been so valuable it has earned me a raise!" Find out more ... Jack Bergstrom Heavy Equipment Mechanic Sharpe Equipment 2.   What is a picture really worth? Marian Tumarkin, co-author of Hydraulics Made Easy and Advanced Hydraulic Control, sent me an interesting article published in the BBC's News Magazine, called: Diagrams that Changed the World. One of the examples the article's author Marcus Sautoy cites, involves Florence Nightingale. As Sautoy explains: "Although better known for her contributions to nursing, her greatest achievements were mathematical. She was the first to use the idea of a pie chart to represent data. She had discovered that the majority of deaths in the Crimean War were due to poor sanitation rather than casualties in battle. She wanted to persuade government of the need for better hygiene in hospitals but realised that just looking at the numbers was unlikely to impress ministers. But once those numbers were translated into a picture - her 'Diagram of the Causes of Mortality in the Army in the East' - the message could not be ignored." A good diagram is indeed worth a thousand words (or numbers in Nightingale's case). It can also be worth a lot of nickel. Consider the four main types of hydraulic diagrams in common use -- and the consequences of having to manage without them: Block Diagrams show the components of a circuit as blocks joined by lines, which indicate connections and/or interactions. Cutaway Diagrams show the internal construction of the components and flow paths. Because these diagrams typically use colors, shades or patterns in the lines and passages, they are very effective at illustrating different flow and pressure conditions. Pictorial Diagrams shows a circuit's components and piping arrangement. The components are seen externally and are usually in a close reproduction of their actual shapes in scaled sizes. This aids in component recognition and identification. Graphical Diagrams are the shorthand system of the fluid power industry. They comprise simple, geometric symbols, drawn to ANSI or ISO standards that represent the components, their controls and connections. To a technician skilled in reading and interpreting them, a graphical circuit diagram or schematic is a valuable aid in identifying possible causes of a problem. And this can save a lot of time and money in a troubleshooting situation. If a schematic diagram is not available, the technician must manually trace the actual, physical circuit and identify its components in order to isolate possible causes of the problem. This can be a time-consuming process, depending on the complexity of the system. Worse still, if the circuit contains a valve manifold, the manifold may have to be removed and dismantled - just to establish what it's supposed to do. Because if the function of a component within a system is not known, it can be difficult to discount it as a possible cause of the problem. Schematic diagrams eliminate the need to reverse engineer the hydraulic system. Where are YOUR hydraulic schematics? As most hydraulic technicians know from experience, there's usually a better than even chance that a circuit diagram will not be available for the machine they've been called in to troubleshoot. But this is unlikely to bother the technician, because it is the machine owner who usually pays for its absence through prolonged service calls and increased downtime. Where do all the hydraulic diagrams go? They get lost or misplaced, they don't get transferred to the new owner when a used machine is traded, and in some cases they may not be issued to the machine owner at all. Why? Because generally speaking, hydraulic equipment owners don't place a lot of value on them. So if you're responsible for the upkeep of hydraulic equipment and you don't have schematic diagrams for your existing machines, try to obtain them - BEFORE you need them. And always ensure that you're issued with schematic diagrams for any additional hydraulic machines you acquire. It's a picture which can be worth a thousand dollars. "This book has the potential to save many organizations lots of money. It should be on the bookshelf of every engineer, supervisor, planner and technician who deals with hydraulic equipment... it's worth its weight in gold." Find out more Alexander (Sandy) Dunn Plant Maintenance Resource Center 3.   Another piece of paper you shouldn't be without A schematic diagram isn't the only piece of paper worth its weight in gold to a savvy hydraulics user. In my article in the November 2010 Issue of Hydraulics and Pneumatics available here, I explain what the other is and why it too is so valuable. 4. Content for your web site or e-zine Need some fresh content for your web site or e-zine? You now have permission to reprint these 'Inside Hydraulics' articles on your web site or in your e-zine, provided: 1. Each article is printed in its full form with no changes. 2. You send an e-mail to editor@hydraulicsupermarket.com to advise us where you'll be publishing them. 3. You include the following acknowledgement at the end of each article: About the Author: Brendan Casey has more than 20 years experience in the maintenance, repair and overhaul of mobile and industrial hydraulic equipment. For more information on reducing the operating cost and increasing the uptime of your hydraulic equipment, visit his web site: http://www.HydraulicSupermarket.com 5. Help us spread the word If you've found our 'Inside Hydraulics' newsletter interesting and informative, then chances are you have a colleague who would too. Help spread the word about 'Inside Hydraulics' by forwarding this issue to a colleague. If they share your interest in hydraulics, then they will surely appreciate being told about this newsletter. New subscribers can get the newsletter by completing the form at http://www.insidersecretstohydraulics.com 6. Tell us what you think We would love to hear what you think of this issue of our 'Inside Hydraulics' newsletter. And of course, if you have any suggestions for future issues, please send us those too. Just e-mail the editor at: newslettersuggestions@hydraulicsupermarket.com Copyright 2000-2010 by HydraulicSupermarket.com. All rights reserved.

To subscribe to this newsletter, go to: http://www.insidersecretstohydraulics.com This issue was sent to the following e-mail address: abelkefa.tools@blogger.com

Air, how load-sensing reduces heat.

Hello again Air,

In your past couple of hydraulic maintenance emails,
I explained how to accurately assess the condition
of a hydrostatic transmission using case drain flow.

Today I want to switch gears and talk about
a type of hydraulic control in widespread use,
but not well understood: load sensing.

Load sensing is a term used to describe a type of
variable pump control used in open circuits. It is
so called because the load-induced pressure downstream
of an orifice is sensed and pump flow is adjusted to
maintain a constant pressure drop (and therefore flow)
across the orifice.

The 'orifice' is usually a directional control valve
with proportional flow characteristics. But a needle
valve or even a fixed orifice can be employed,
depending on the application.

In hydraulic systems that are subject to wide fluctuations
in flow and pressure, load-sensing circuits can save
substantial amounts of input power.

A load sensing circuit typically comprises a
variable displacement pump, usually axial-piston design,
fitted with a load sensing controller, and a directional
control valve with an integral load-signal gallery.

The load-signal gallery is connected to the load-signal port
on the pump controller. The load-signal gallery in the
directional control valve connects the A and B ports of
each of the control valve sections through a series of
shuttle valves.

This ensures that the actuator with the highest load pressure
is sensed and fed back to the pump control.

To read the rest of this story - with diagrams,
point your browser to
http://www.insidersecretstohydraulics.com/load-sensing.html

Yours for better hydraulics knowledge,

Brendan Casey
Author of 'Insider Secrets to Hydraulics'

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Air, a final word on hydrostatic transmission leakage.

Hello again Air,

In your previous two hydraulic maintenance emails,
I explained how to correctly determine the condition
of a hydrostatic transmission using case drain flow,
and discussed the role and influence of a flushing
valve when doing this.

Today I want to clarify one last source of confusion
about the influence of the charge pump when assessing
case drain leakage from a hydrostatic transmission.

It is sometimes assumed if the charge pump relief vents
into the case of the pump, transmission pump leakage
can be determined by subtracting charge pump flow from the
total flow from the pump case.

For example, if total charge pump flow is 10 GPM and the
flow-meter in the pump case drain line is reading 15 GPM
then transmission pump leakage is 5 GPM (15 - 10 = 5).

This is incorrect because it suggests that a hydrostatic
transmission can leak more than the total available flow
from its charge pump. It cannot.

That is, it is impossible for the flow meter in the pump
case drain line to read 15 GPM when the total available
flow from the charge pump is only 10 GPM, as in the
above example.

The reason is simple. Because the function of the charge
pump is to make up losses from the loop through internal
leakage, if total losses exceed available charge pump flow,
the transmission will cavitate.

If in the above example, the transmission was leaking 5 GPM
more than the total available flow from the charge pump,
there would be a serious deficit of fluid in the loop.

In practice, the transmission would destroy itself through
cavitation before it got to this point.

Let me explain this another way. Let's assume we have a
transmission that has a volumetric efficiency of 100%,
that is, the pump and motor have no internal leakage.
The loop has a total volume of two gallons and is full
of fluid. Because there is no internal leakage there
is no need for a charge pump.

The pump is stroked to maximum displacement, which circulates
the two gallons of fluid in the loop at a rate of 50 GPM.
Because it's a closed loop, with no leakage, the flow from
pump to motor is 50 GPM and the flow from motor to pump
is 50 GPM.

Now let's introduce internal leakage of 0.5 GPM in both
pump and motor. The result is that, with no charge pump
to replenish the loop, after one minute there will only
be one gallon of fluid left in the loop (the other gallon
will have leaked back to tank). Within a second of the
transmission starting to leak, the transmission pump
will start to cavitate and the severity of this cavitation
will increase with each passing second until
the transmission destroys itself.

Now let's install a charge pump with a flow rate of 1 GPM
in the circuit. Problem solved, temporarily at least.
With 1 GPM leaking out of the loop and 1 GPM being
replenished by the charge pump the status quo is maintained...
until wear causes the internal leakage of the transmission
to exceed 1 GPM.

As you can see, it's not possible for the internal leakage
of a hydrostatic transmission to exceed the flow rate of
its charge pump. Charge pump flow rate is typically 20%
of transmission pump flow rate.

This means that volumetric efficiency can drop to 80%
before the transmission will cavitate and destroy itself.

The trick is to overhaul the transmission
BEFORE this point is reached.

Yours for better hydraulics knowledge,

Brendan Casey
P.S. If you've struggled with any of the concepts
in these past three bulletins on hydrostatic transmissions,
you'll find the simulation videos
in 'Hydraulics Made Easy' a BIG help:
http://www.hydraulicsupermarket.com/hydro-tranny

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West Perth, Western Australia 6872
Australia
6 (189) 380-6659

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