Actuators ex Libris: Hydraulic Power

Actuation and mechanical engineers go together like lamb and tuna fish.  Yet there are plenty of engineering schools that do not even touch the subject as it applies to the practical world, and above all else, how it applies to industry.  But man I am sure glad I learned to make that black box model.  The standard google search for designing actuation systems will leave you high and dry unless you use the right keywords which you conveniently don't know.  Lucky for whoever is reading this, my stumble-upon searches usually end up at some tech resource.

Enough crap, lets get to the good stuff.  Actuators are used to provide displacement in a mechanical system. The traditional actuator provides linear, or single axis displacement usually in the form of cylinder slides.  Actuation is provided primarily by electronic solenoids, pneumatics, and hydraulics. Gear systems (depending on how you look at it), can also be used but present an additional design element.  As general rule of thumb, system power and size increase in magnitude from:

electronic solenoids -> pneumatics -> hydraulics

Electronic solenoids and pneumatics generally provide forces up to the order of 100lbf, while most hydraulic actuators provide forces in excess of 10,000lbf.  

Actuators require a complete power system to function.  System design is the challenge engineers face, whether manufacturing the components or building the systems.  This article will address hydraulic power, but pneumatic systems are very similar operating on the same fluid principles and often using very similar components.  A basic actuation system is comprised of two main components: motive power and actuation.  The power in the system follows:

Motive Power -----> Transport Medium -----> Actuation

Electronic solenoids are simple, typically powered by a controlled AC/DC power source, the transport medium electrical wire connecting the components.  Pneumatic and hydraulic systems are slightly more complex, requiring a few more components.  The motive power is provided by a pump, and the transport medium consists of piping and valve controls.  It is worth noting a pump is comprised of two components: a motor and pump head (A topic to be discussed in a future article). A general hydraulic system is illustrated by:

Parker Hydraulics is a high end hydraulics manufacturer, and is also a great place to start for system components and information.

Self Evaluation Try Two

Well I did not really know where to start with myself so I took a look at my first Self Evaluation post and I have to say, I have definitely improved in all aspects of my blog.  I have doubled my blog content with relevant posts that reflect engineering tools.  I have increased my comments on other's blogs, but unfortunately have not received many comments on my blog that I can reply to.  My posts strive educate the reader about engineering tools and their uses.  I have incorporated many types of media into my blogs including hyperlinks, self-taken / create photos, and tutorial videos.

The Voltmeter

A voltage detector is essential tool to every handyman, craftsman, tradesman, and engineer.  The handyman and craftsman would use the small analog voltmeter in the bottom right to measure small time voltages every so often. The tradesman would use the voltage detector at the top in red to check high voltage levels from 120V to 600V.  The engineer would use the voltmeter, or more specifically digital multimeter (DMM) located at the bottom left in yellow, to measure circuit values.  Anyone and everyone should have the pencil voltage detector in yellow at the top right to detect the presence of electrical potential without any contact.  This little guy can and has saved many lives.

Today I will focus on the DMM, since it is widely used in engineering.  A good multimeter should be able to test AC/DC voltage, AC/DC current, resistance, continuity, diodes, and capacitance.  Some meters may also feature transistor testing, a nice feature.  A good multimeter should cost around $100-$150 and should have a replaceable fuse (try and get a few spares because if you mess up measuring current you will for sure blow a fuse).  The video below teaches the basics of electronics components and taking measurements with a DMM.

The Real Deal With Global Warming

Everyone is taking this global warming junk way to seriously.

Most everyone is aware of the two sides to global warming: Its gonna happen and we're all gonna die, or its a big hoax and we have all been deceived. Pro global warmingites view humans and their machines as the main source of global warming via the green house effect. Anti global warmingites think the earth warming up is part of its natural cycle.

In my expert opinion, both sides are correct.  There is no doubt that the earth has a natural warming and cooling cycle, resulting in other earthly cycles such as amount of carbon dioxide in the air.  There is no  doubt the mankind and its mega machines have increased the amount of carbon dioxide in the air.  Anyone who says otherwise is simple mistaken.  The global warming theory focuses on this massive amount of carbon dioxide produced by man and states (via the greeenhouse effect) the earth is going to warm up and things are gonna melt and cities will flood and godzilla will possibly rise from the ocean. Yes this could happen, but lets think about it, nothing like this has ever happened in the past at even greater concentrations of greenhouse gases in the atmosphere.  There are so many details about the earth that play such an important role in climate change that it is impossible to accurately predict global warming.  It would be like putting a dog in the grocery store and trying to predict where he would go and what he would eat.  The point is yes we are most likely causing the earth to warm up a little faster but the climate cycles will take care of it and it will be like nothing ever happened.

Besides, the Masters (Lewis and Floorwax of 103.5 The Fox) revealed a study that cow (and other animal) farts are the second leading cause of carbon dioxide emissions.  I really think we should focus our resources on that instead of humans.

The Vernier Caliper

A pair of calipers is the engineer's right hand man, at least for mechanical engineers anyways. The earliest caliper date back to 6th century BC used by (surprise surprise) the Greeks.  I am not here to give a history lesson because I hate history, I am here to tell you how to use one of the most basic and common types of caliper, the Vernier Caliper.  The basic layout of the Vernier Caliper is shown below.  This information is pulled straight from the Caliper Wiki but it is important enough to restate here.

1. Outside Jaws: Used to measure an external dimension
2. Inside Jaws: Used to measure internal dimension
3. Depth Probe: Used to measure a depth dimension
4. Main Scale Top: Millimeter (mm) scale
5. Main Scale Bottom: Inch (in) scale
6. Vernier for mm: gives interpolated measurements to 1/10 mm or better
7. Vernier for in: gives interpolated measurements to 1/128 in or better
8. Retainer: Used to lock slide into place

Below is a video from this Vernier Tutorial that shows the correct way to use a pair of Vernier Calipers.  I recommend you visit the site for an in-depth analysis.