And the survey says. . .

Julie Ritchie has been conducting market research at Penton (the company that publishes H&P) for more than 20 years. As is typical of the “old-time” Penton people, Julie takes pride in her work and absolutely will not sacrifice credibility.
Julie sent me a copy of a readership survey, which was e-mailed at random to 10,000 subscribers — about 1/5th of our total. It looks like a very accurate survey because the results mirror the facts.
One fact is that of our total of 51,021 qualified subscribers, 6478, or 12.7%, receive the digital version of H&P. In Julie’s survey, 14% indicated that they receive the digital version. That’s not exact, but it’s pretty close, and probably excellent results for a random sample survey.
As with most surveys, this one consisted mainly of multiple choice questions. This makes it easy to tabulate results and post them into charts and graphs. But what I really like about Julie’s surveys is that she gives participants an opportunity to enter comments in their own words.
Question #3 of the survey asked readers why they prefer to receive the magazine in the format they do — print or digital. The top three responses among print subscribers were that it’s easier to read, it can be read any time, and it’s easier to carry, in that order.
But I was surprised at the #1 answer among those receiving the magazine through their computer: it’s environmentally friendly. Now this is purely speculation, but I presume that the average age of these readers is less than the average age of readers who receive the magazine in print. If this is true, then you could conclude that the younger readers are more likely to conserve paper than the older ones are.
If this is true, then techniques for designing more environmentally friendly fluid power systems must be of keen interest to these younger readers, and I suspect it is. But this is nothing new. We’ve stepped up our coverage relating fluid power systems to the environment for years.
This survey was conducted primarily for demographics, to learn the information-gathering habits of the “typical” reader. But Julie also conducts surveys to find out what type of information readers are looking for — what they like, don’t like, what they’d like to see more of, etc. So when the time comes for that kind of survey, I’ll be eager to see if environmental issues are among the top interests of readers.

Hydraulics — a modern marvel

Modern Marvels has been a long running series on The History Channel — known today, simply, as History. The producers never seem to run out of ideas, and they always do a great job with their presentations.

Back in 2004, The History Channel released an episode on hydraulics. Although I have a couple minor issues with the content, in general, I think the producers did a superb job.

They present the content in a way that would interest people well-versed in hydraulics, who know nothing about it, or anyone in between.

I found a link that previews the first five minutes of the episode. To view it, click here. And if you download the Veoh web player, you can watch watch the entire 45-min episode. Or go to History's website, and buy the DVD.

I corresponded with one of the producers of Modern Marvels to suggest they create an episode about pneumatics. He asked me to provide some impressive examples of pneumatics, but I didn't hear back from him. But who knows, maybe some day. . .

Dealing with stress

I don't know who the author is, but the following advice sounds pretty good to me.

A lecturer, when explaining stress management to an audience, raised a glass of water and asked, "How heavy is this glass of water?"
Answers ranged from 20g to 500g. The lecturer replied, "The absolute weight doesn't matter. It depends on how long you try to hold it. If I hold it for a minute, that's not a problem. If I hold it for an hour, I'll have an ache in my right arm. If I hold it for a day, you'll have to call an ambulance. In each case, it's the same weight, but the longer I hold it, the heavier it becomes."
He continued, "And that's the way it is with stress management. If we carry our burdens all the time, sooner or later, as the burden becomes increasingly heavy, we won't be able to carry on. You have to put the glass of water down for a while and rest before holding it again. Likewise, once you're refreshed, you can carry on with the burden.
"So before you return home tonight, put the burden of work down. Don't carry it home; you can pick it up tomorrow. Put it down, and don't pick it up again until after you've rested a while."

Here are some tidbits from the same author:

* Accept that some days you're the pigeon, and some days you're the statue.

* Always keep your words soft and sweet, just in case you have to eat them.

* Always wear stuff that will make you look good if you die in the middle of it.

* Drive carefully. It's not only cars that can be "recalled" by their maker.

* If you can't be kind, at least have the decency to be vague.

* If you lend someone $20 and never see that person again, it was probably worth it.

* Your sole purpose in life may simply be to be kind to others.

* Never put both feet in your mouth at the same time or you won't have a leg to stand on.

* Nobody cares if you can't dance well. Just get up and dance.

* When everything's coming your way, you're in the wrong lane.

* Birthdays are good for you. The more you have, the longer you live.

* You may be only one person in the world, but you may also be the world to one person.

* Some mistakes are too much fun to only make once.

*A truly happy person is one who can enjoy the scenery on a detour.

* We could learn a lot from crayons... Some are sharp, some are pretty and some are dull. Some have weird names, and all are different colors, but they all live in the same box.

There's no business like...

Through the years, I've been fortunate enough to sometimes write and edit article dealing with the entertainment industry. These usually involved thrill rides at amusement parks but also included special effects used in movies and in live theater. Developing these articles generally turns up much more information than space allows to print or that deviates from the magazine's focus of system design.

One article I remember in particular involved an interview with Dan Hoffman, of Showtech, Inc., I learned how he sometimes has to overcome directors' fears or negative perceptions of hydraulics. Dan said this problem usually is overcome once a director discovers that hydraulics was instrumental in the success of other impressive effects. For example, in a production of Peter and the Wolf, Showtech was called on to supply a mechanism that would whisk an actor ten feet off the ground to the top of a tree in about a second with rigging not visible to the audience.

Dan housed a hydraulic power unit and cylinder inside the tree trunk and connected a block-and-tackle assembly to the cylinder rod to gain mechanical advantage. The block-and-tackle arrangement multiplied the stroke of the cylinder but divided its force by an equal factor. This meant hydraulics was the only choice for generating the high force and rapid linear motion needed. A cable on the output end of the block-and-tackle assembly ran inside a low hanging tree branch containing a track. Hooking the end of this cable to a harness on the actor and activating the hydromechanical system gave the impression that the actor lept ten feet from a standing position without any visible cables.

Another problem is how financially risky show business can be for those who are not involved directly. Dan said that in legitimate theater, a contractor like Showtech often can win or lose a bid based on a prep charge. A prep charge is the fixed cost a contractor charges a production company to complete the project at hand. The rest of the money comes from the lease agreement between the contractor and production company. What makes the financial picture so risky is that the contractor has to predict how well a show will do when figuring fixed and contract charges. If he thinks a show will do well -- and, therefore, run for a long time -- he can recover his investment just on the lease agreement and not even quote a prep charge. However, if he thinks a show may close after only a brief run, he will tend to quote a high prep charge because a short lease term will not cover his investment.

What complicates matters even more is competition. If a competitor thinks a show will do well but you don't, you'll likely lose the contract because of your higher prep charge. So trying to win a contract tends to keep your prep charge low, but minimizing risk tends to keep it high. But I guess that's show business.

An early lesson in motion control

One of my favorite toys as a pre-teen was a tape recorder, which brought many, many hours of creative entertainment. After recording various bodily function noises (some genuine, others fabricated) toilet flushings, etc., my friends and I graduated to making parodies of TV and radio commercials, TV shows, and even made our own skits. But my first tape recorder also taught me my first lesson in drive design, although I’m getting ahead of myself.

My first tape recorder was a real cheapie, and quite primitive. We’re talking about the old reel-to-reel jobs — early sixties, just before cassettes fell into favor. This machine drove a takeup reel at a constant rotational speed to pull the tape past a record and playback head. The trouble is, as more and more tape wound around the takeup reel, its effective diameter increased, so the tape at the beginning of the reel traveled at a slower linear speed than tape did at the end.

This simple setup posed no problem as long as I recorded and played back tapes on the same machine. However, I noticed a big difference when I got my second reel-to-reel machine. The new one worked great, but when I played back tapes that had been recorded on the old machine, the speed was off. The beginning of tapes played too fast, and the end of tapes played too slow. Further study revealed the problem.

The new reel-to-reel machine used what I later learned is called a capstan drive. Capstans were used by most reel-to-reel tape recorders, and many years later I learned that they are used extensively in industry. They serve as an effective way to maintain constant linear speed of material winding onto or unwinding from a spool or reel.

Unlike my first tape recorder, the second one’s motor didn’t drive the tape takeup spindle directly. Instead, it drove the spindle through a torque-limiting clutch. The clutch transmitted just enough torque to spin the takeup reel and apply tension to the tape. The tape itself got pinched between a pair of rollers (the capstan) spinning at a constant speed. This allowed the tape to run at a constant speed, regardless of how much tape was on the takeup reel.

So even though this wasn’t my first lesson in fluid power, it did provide an important lesson in drive design and motion control. I just didn’t call it that.

Catching forty winks

As Labor Day weekend approaches, I reflect on the era when the Monday after Labor Day meant the opening of the SAE Off-Highway Show in Milwaukee. The first time I attended an SAE Off-Highway Show was in 1981, during my first year as an editor. I worked for a different magazine then, Power Transmission Design, and that trip left quite an impression. A new chief editor had just been appointed to PTD, and after becoming acclimated to her new position, she realized that no editor had yet been assigned to cover the Off-Highway Show. So the week just before the show, I was instructed to arrange travel arrangements to attend.
The show was doing pretty well then, so there wasn’t a hotel room to be had in downtown Milwaukee. This meant I’d have to rent a car and stay on the outskirts of town somewhere. No problem. After many attempts, I finally landed a room — at the 40 Winks Motel.
I arrived at the 40 Winks, then drove downtown the next morning to attend an editor’s breakfast and press conference. About ten of us were seated at a table, and most of these guys obviously knew each other. Now keep in mind, I only 27 at the time, and had only been an editor for a few months. Prior to that, I didn’t know the difference between a font and a sidebar, so I felt a little intimidated and apprehensive. But I don’t remember doing or saying anything to embarrass myself.
Eventually, the conversation drifted to where each person was staying. One guy made some remarks about his room at the Hyatt. The man to his left was staying at the Marc Plaza. A couple others were at the Pfister. Each man took his turn, moving clockwise around the table. I remember thinking (or maybe it was a silent prayer), “Please let the conversation switch to something else before it’s my turn. I don’t want to say I’m at the 40 Winks.” Fortunately, the topic of conversation did change before it was my “turn,” so I was off the hook.
I had a pleasant stay at the 40 Winks and have even gone back a couple times. It seemed like a ma-and-pa operation at the time, and has gone through at least one expansion — so they must be doing something right. Unfortunately, I don't have many business trips to Milwaukee any more; the last one was probably 10 years ago. I remember seeing a sign at the 40 Winks about rooms with water beds. So the last I stayed at the 40 Winks, I requested a room with a water bed. The bed was comfortable enough, but I couldn't help but think what must've gone on in that room after seeing the giant mirror mounted onto the ceiling!

Focus on efficiency

It’s always a good idea to design for efficiency whenever you can. But efficiency can be a hard sell unless the buyer or management sees higher efficiency as a smart investment.
I visited a Baldor Electric, a manufacturer of electric motors, drives, and, controls, and learned about substantial reductions in electricity costs that can be had simply by specifying higher efficiency motors. The presentation was geared toward general-purpose motors in the manufacturing plant, but energy savings could also become a selling point if you specify electric motors for hydraulic power units.
John McFarland, president and CEO of Baldor, pointed out that more than 97% of the money spent on a motor goes toward the electricity to run it. More specifically, the average 3-phase, 50-hp, 1800-rpm motor will consume $36,029 worth of electricity if operated continuously over the course of a year. This assumes a very modest $0.10/kW-hr rate for electricity and motor efficiency of 90.7%. However, a premium efficiency (94.5%) motor operating under the same conditions would consume $34,580 worth of electricity. McFarland noted that the $1449 savings in the first year alone would almost pay for the entire motor -- not just the difference in price. Now multiply this saving by an expected life of ten years (which seems rather conservative), and the cost of a $2000 motor compares to a total cost of $360,000.
Granted, most motors aren’t 50 hp and don’t operate fully loaded 24/7. However, for most industrial hydraulic systems, the power unit’s electric motor is running whenever the machine is on. And in many cases, the motor runs fully loaded most of the time. So if the power unit is running 16 hr/day, six days a week, the savings can still be substantial.
Literature provided by Baldor lists figures for motors sized from 1 to 200 hp, so let’s look at a situation more typical of an industrial hydraulic system. According to Baldor, a standard 10-hp motor has an efficiency of 86.1%, which would use $7591 worth of electricity annually if operated continuously. But 4800 hr/yr seems more reasonable for a typical power unit. This amounts to 16 hours per day, six days a week, with two weeks off, which translates to $4159/yr. Baldor publishes their 10-hp premium motor as having an efficiency of 91.7%, which would consume $7127 of electricity annually. Again, though, at 4800 hr/yr, this would translate to $3905 -- an annual savings of $254.
But if the motor runs only about 55% of the time, then we should upgrade its expected life proportionally -- to 18.25 years. So for our example, the total energy cost savings from specifying a premium efficiency motor would amount to $4635. And don’t forget, these figures are based on electricity at $0.10/kW-hr. Ten cents is too low for situations, and rates will likely increase even more over time.
After the formal presentation, someone remarked that many designers are well aware of the benefits of specifying more energy efficient components. The problem is that sometimes the people who won’t approve spending a little more for higher energy efficiency are the same ones who threaten to cut jobs if expenses (such as the electricity bill) are not reduced. Therefore, because you have read this far, it now has become your task to share this information with whoever has been complaining about your facility’s electricity bill.

Hyped up over hybrids

Seems like everything is hybrid these days. My dad had a degree in agriculture from Michigan state, and I remember him telling me about how crops were bred to produce hybrid species that were highly resistant to certain diseases, drought, and other conditions — and that was more than 40 years ago.

Ever since the introduction of hybrid cars, we see the word hybrid popping up everywhere. A news release arrived awhile back describing a new hybrid excavator from Doosan Infracore, Atlanta, scheduled for launch in North America in 2012.

Why is this excavator a hybrid? The release explained that the excavator “will be equipped with a diesel engine, electric swing motor, electric converter, and an ultra-capacitor that will store excess energy during turning and light-duty operations. The reserve electricity will then be used to assist the power of the engine during heavier work; allowing the engine to maintain low revolutions and high efficiency combustion during acceleration.”

Now I’m not surprised that Doosan is replacing the conventional hydraulic swing drive with an electric drive. Hydraulic gear motors are normally used for this function. And although gear motors are powerful, reliable, inexpensive, and extremely compact, they’re not especially efficient. Plus, the rotary output of a hydraulic motor can easily be accomplished with an electric motor — even if the electric package must be larger and heavier. So it stands to reason that if efficiency is your primary goal, you’d consider using an electric motor for the swing drive.

However, Doosan could probably save all that trouble by using a moreefficient bent-axis piston motor instead of the gear motor and use an accumulator instead of the “ultra capacitor” for energy storage. Plus, the hydraulic solution would eliminate the likelihood of overheating the motor and avoid the potential dangers of electricity. After all, excavators are often used near water and out in the rain.

But what I found more puzzling was that Doosan made no mention of using a hydraulic fan drive to cool the excavator’s diesel engine. Hydraulic fan drives can substantially improve fuel efficiency and reduce emissions of diesel engines. How substantial? According to Gary Gotting, of High Country Tek, a manufacturer of electronic controls (including those for hydraulic fan drives), testing has shown that simply replacing a vehicle’s conventional belt-driven fan with a hydraulic fan drive can cut fuel consumption by 14.5%.

For the record, I contacted Doosan to find out what type of drive this machine will use for its cooling system. I was told it uses a conventional belt driven fan drive. Therefore, if Doosan’s goal is to produce the “greenest” excavator on the market, I think they’re missing out if they don’t investigate the virtues of hydraulic fan drives. These fuel savers have been popping up in all kinds of off-highway equipment. They’re just not getting all the hype of hybrid electric drives.