For years Modular Elevator Manufacturing has been educating the public on elevators in general and the benefits of hydraulic elevators specifically. Hydraulic elevators are often times the absolutely best option for vertical travel, especially when it comes to low-rise applications. However, we have not spent an inordinate amount of time discussing many of the drawbacks. That is because there are very few and generally well understood. However, it has come to our attention that some of these drawback have taken on a life of their own and now live on in near mythic proportions.
So in this short article we are going to address the ups and downs of the hydraulic elevator, dispel myths and shed some light. This is not a sales pitch! After all you can buy a high-quality, commercial hydraulic elevator from any number of companies. We look at this article as a help to those that are truly curious about the best elevator for their current or future elevator project.
To keep me organized and to keep from jumping all over the place, I will address each point listed below. These are the largest complaints that many have about hydraulic elevators:
Believe it or not, there is merit to some of the claims made above, but the explanations are often ignored and this has led to more than one exaggeration. That begs the question, why would one perpetuate a misleading claim? I hate to say it, but sales and profit motives are usually big factors. If more money can be made, why sweat the small things like the truth and developing a reputation over time. After all, the elevator industry has such a stellar reputation, why damage it for a few dollars? Just kidding on the reputation crack. One of the biggest battles we face as an elevator manufacturer is the overall reputation of the industry as a whole.
Ask nearly any general contractor, building owner or architect and they will affirm they dislike the elevator business. In my experience and when doing independent research I have personally heard elevator companies described as bullies, untruthful, unreliable, unresponsive and overpriced. Do any of those descriptive terms surprise you? Unfortunately, probably not. So let’s just say that profit motives are powerful and can lead to some generalizations and exaggerations. But more than that, in the late 1990’s a new product was introduced to the American market. The MRL (machine room-less) traction elevator was rolled out with tons of fanfare and major investment from big elevator companies.
Logically, for that investment to payoff significant downward pressure was applied to sell up MRLs. Incentives were created, promises were made and poor comparisons were projected. Those sometimes false comparisons still ruminate in the minds of many. This coupled with ignoring hydraulic elevator technological improvements leads to a misunderstanding of facts and benefits. But let’s get to the list.
The first common complaint is that hydraulic elevators cost too much. Not necessarily in the upfront investment in installation, but in the Life Cycle Cost or LCC. The initial cost of a hydraulic unit runs around 35% less that a traction MRL. Not only is that true of pricing at Modular Elevator Manufacturing, but across the board, but what about maintenance and electricity? How does hydraulic stack up against MRL traction?
This question was answered by a study from of all places Thyssenkrupp. They were so interested in this question that they commissioned a report and then published its findings in a blog. The answer may surprise you. They found the following:
“We conducted Life Cycle Costing (LCC) research on low-rise elevators to help customers understand their economic and environmental impacts. LCC looks at the costs involved with a product or service over its entire lifetime. The study showed that over 25 years, the cost to maintain three-stop traction MRL is $173k compared to the same hydraulic MRL which cost $91k.”
Myths about Low-Rise Elevators Means Realistic Costs to Building Owners – Tetley-Scott 2014
Keep in mind that is the cost to maintain the elevator, not buying it and install it as well. That is a stunning admission. They are in basic terms saying that an MRL traction is, give or take, seven grand out of your pocket every year when a hydraulic is only three thousand-seven hundred. That is for the same travel distance and same number of stops. Cost wise hydraulic is the only logical choice. This is especially true when you add in the initial investment cost.
Regarding electricity, the same blog post points out, “In fact, a 2,500 lb. elevator, traveling a single floor (12 feet) at 100 fpm (feet per minute) and operates 100 runs a day, does not even use $600 worth of energy in an entire year. So assuming the hydraulic uses more energy than traction, you could have a differential of perhaps just $150 a year in energy cost.” In other words, in the whole picture, although a hydraulic elevator may use more electricity in a year, it is negligible to say the least.
It is an old canard that hydraulic elevators use significantly more energy than a traction. If it were true, we would produce counter-weighted hydraulic systems. It would be easy enough to do, but who on earth would pay so much up front and then have a more additional maintenance costs of weights and ropes? They make no sense because the electric cost is so low and going down every year as efficiency in hydraulic pumps and motors increase.
This is no old myth. When hydraulic elevator were first installed there were a couple of factors that made them less green than their traction counterparts. The hydraulic fluid used was not bio-degradable and the oil was in a jack underground where leaking could not be effectively monitored. It was a time bomb of sorts as rust and corrosion slowly wore away at the hole lining, jack and bulkhead. The seals were more prone to failure and the drips turned into steady streams of lost fluid.
There are still hundreds of these old systems in place today. And they are either, by some miracle leak free, they are not being routinely checked for oil loss or the person paying the bills would rather buy a five-gallon bucket of oil every quarter than have the jack pulled and replaced.
But things have changed. In many applications you can use above ground jacks and better materials are available when an in ground jack is needed. Generally, PVC filled with sand is in the hole and then the jack is inside the PVC. If installed properly there should be no leaking at all.
Also, the elevator code has recognized the need for improved environmental awareness. If the code is followed, environmental issues should be non-existent to rare. If there are any problems or accidents of an environmental nature it is more than likely due to unqualified installers. Current technology affords jack leak monitoring systems and all the jack components are better than in years past. This coupled with good maintenance and record keeping should significantly reduce any hydraulic fluid escaping into the ground.
But what if it does? Good question. The last line of defense are interceptors for spilled oil that separate the oil from water protecting the environment against leakage. And also you now have the choice of many bio-degradable hydraulic fluids formulated for elevators. Oil replacement and additional testing is necessary so the elevator technician needs to know of this choice. But there is no real need to worry about leaks if you don’t want to with improved rules and technology.
Okay hydraulic elevators are slower. But does that matter? I really could write an entire article on this subject…as a matter of fact I already have. You can check it out here. You can read it if you are really interested, but for everyone else let me cut the the chase. Speed is really needed if you are going over six or seven stories for sure and maybe a wanted convenience you would like going over four or five stories. But for anything below that you are not getting your money’s worth.
The reason is due to limits of the human body and how fast an elevator can get to top speed and still be a comfortable ride. If you are traveling just 30 or so feet you would just barely get to top speed before starting to slow down again for the next stop. Top speed is rarely to never hit in a typical three stop elevator. Think about it, you would be thrown to the floor or pasted to the ceiling if you traveled to top speed any faster. So yes, hydraulic elevators are slower, but for low-rise applications it is not that important at all. Yet everyday we send out Fast Track budget numbers to people that are convinced they need a jet pack for 10′ to 20′ feet of travel. The need for that much speed does not exist.
To increase speed at a lower cost a roped hydraulic is a great option if you are going over three or four stories. It combines a hydraulic system with a pulley wheel at the top of the jack. This speeds up the elevator and increases the total height of travel.
Although limited, hydraulic elevators may go higher than you thought. Two or three stops are just the beginning. I have seen hydraulic elevators installed up to six stops. That is with over 60′ of travel! The chart below shows a comparison of what MEM can provide and associated travel. Keep in mind these are only general numbers.
The important thing is to weigh all the options available and not make any snap decisions without some research. For building owners and managers, that may mean asking some hard questions of your team and comparing costs to benefits. For the architect it may mean thinking outside of the elevator cab. Look for a better technology, before you drop in the same footprint. For the GC you might need to call and ask questions about how other alternatives can make your job easier, not harder when it comes to the elevator installation.
It is important that, when looking at the elevator alternatives, you do not just listen to sales pitches. Doing so will cost you significantly more in both the short and long term. I hope this article makes clear that traction elevators are not a proper alternative for two and three stop projects accept under certain circumstances. Also, hydraulic elevators up to five stories need to be considered. Based on cost and use you may find a hydraulic as the best alternative. Just take a look at the facts, determine your needs, and choose wisely.
You will be keeping your elevator for a long time so seek independent voices. MEM can be a great resource or a qualified elevator consultant. We won’t say one is better than the rest just for a sale. Just find the proper and most applicable mode-of-conveyance for the right application.
If you have a project in mind, or questions about this article or our line of manufactured elevators feel free to contact us for Fast Track budget numbers. Our knowledgeable team will happily advise you on the most effective and beneficial mode-of-conveyance for you and your project. We can provide budgetary numbers in 24 hours.
It is a tough chore deciding on what kind of elevator conveyance you should have in your next building project. As I have said before the elevator industry is very secretive about many aspect of vertical transportation. The wrong elevator is often placed in buildings because the information is guarded so closely. Too many resources can be spent on the improper type of elevator conveyance, not to mention the ongoing cost of maintenance and other factors if a bad fit is chosen. I hope to illuminate just some aspects of that decision in this blog, but let me warn you. Elevators are complex so I can’t cover everything in just one sitting. This will be a continuing series with this being the just the first.
Let’s start with the basics. There are three types of elevator conveyance systems (ways the elevator moves). This is regardless of the cab size or capacity of a commercial quality elevator. I am purposely excluding home elevators from this discussion, however there is a lot of transferable knowledge so stick with me. Any cab or weight capacity can utilize any of the three modes of movement. Those three are traction, hydraulic and roped hydraulic.
Traction is the type of conveyance that most people imagine when they think about elevators. It is the one from the movies with the ropes that people are constantly dangling from. Though the term “ropes” can be a little misleading. Here we go again with the elevator industry using terms that can confuse. Ropes are not what cowpokes use to lasso cattle or magicians use to tie up all too willing assistants. Ropes are actually cables. Elevator professionals understand ropes as highly engineered strands of wire wrapped together. A typical cable or rope can have over 150 strands of wire designed to be strong and flexible for a long time.
Ropes fill the hoistway of a traction elevator. That is because although one rope and pulley could in theory lift an elevator car, it would be inefficient and unsafe. So, in the hoistway you will find several hoisting ropes attached to the car and the counter weights. If you were paying attention in sixth grade science class and learned about pulleys and multiplication of force, you know why. Ropes are also redundant for safety.
Then there is a governor rope used to stop the car if there is a failure. If the elevator starts traveling too fast, the governor rope’s movement tells the brakes to stop the car. Lastly there are compensating ropes. Ropes can get heavy (up to 1.85 pounds per foot). Compensating ropes are attached to the car and counterweights to make up for the weight difference. All these ropes and sheaves (really pulley wheels) raise and lower the car.
However, despite appearing with Bruce Willis, Keanu Reeves and Spiderman (see the link at the end for a fun video on elevators in movies) traction elevators may be a star but, is not the the most common type of elevator conveyance. This is due to the attributes that make this type of elevator more conducive to taller buildings. As there are more low-rise or short buildings than high-rise buildings, hydraulic is much more common.
Hydraulic elevators are simply one or two hydraulic jacks pushing the elevator car up in the hoistway and then releasing hydraulic fluid to allow it to move down.
The jacks can either be in-ground or above-ground, depending on how high you need the elevator to go. But think about what a hydraulic jack is. In simplest terms it is a cylinder with a piston inside. As you push hydraulic fluid in, the piston goes up. So if you want to move something up ten feet you have to have a piston at least that tall. This means the whole jack must be at least that tall as well. Hence the in-ground jack.
An in-ground jack configuration is a single jack usually attached directly to the bottom of the elevator car. So to increase the height the car can travel, a taller jack must be used and must then be placed in a hole. The travel distance of the elevator dictates the depth of the hole.
Above-ground jacks (as you can tell by the name) are not in a hole. They are usually two jacks at the bottom of the elevator pit (the area at the bottom of the shaft) and attached above the car on either side, or more properly attached to the car’s sling several feet above the car itself on stiles. Logically, the higher the travel distance – the taller the jacks – the higher above the car the jacks must be attached – the taller the hoistway must be to accommodate the system. You may want to re-read that again. I wrote it and had to peruse it several times to make sure it was right.
In any case, to reduce the need of a real deep hole or a real tall hoistway, jacks can be and often are telescopic. Elevators can typically have up to four-stage telescopic jacks. This ultimately increases the useful range of hydraulic elevators overall.
Lastly, roped hydraulic elevators borrow from both systems. Again keeping it simple, this system of elevator conveyance uses hydraulic jacks, not to push the elevator car up directly, but to push an elevator sheave or pulley up that then with ropes raises the car.
How does it work? It has a pulley wheel or sheave mounted at the top of the piston or pistons and instead of it being directly connected to the bottom of the car or above the car on the sling. The sheave goes up or down as the jack is raised or lowered. A rope goes over the sheave and then is anchored to the hoistway below the lowest level of the piston and to the car.
There are clear benefits to this type of elevator, the most important being the 2:1 ratio of car to jack movement created by the use of sheaves and ropes. This provides a greater range of travel and allows for a shorter jack. Because shorter jacks are used greater travel distances can be achieved without an in-ground jack with its associated drilling costs. Also the travel speed is faster than hydraulic elevator at 200+ feet per minute, but the travel distance can easily be over 80 feet as the ropes and sheaves double the effective length of the jacks.
Your head maybe spinning a bit, especially if you generally view elevators as an annoyance that should be avoided at all costs. But, the above can help you start getting a picture of what type of elevator conveyance should be used in a project based on total travel. And let’s face it, cost and travel are the primary factors. Other factors may include speed, design flexibility and even building codes, but nothing can disqualify an elevator type faster than the practical inability for the elevator to travel the needed distance.
Regarding the cost briefly there are several factors to consider. The initial investment, work space interruption, the value of taking the elevator off the critical path, maintenance contracts and even operating costs. We will explore each of these in future posts, but again to keep it simple. Traction elevators are far and away the most expensive to buy and maintain. Roped hydraulic is next and finally the workhorse of the industry hydraulic is the least expensive. You must however, consider overall travel capabilities when deciding on your elevator. Take a look at the chart below.
The chart is for general guidelines. But as you can see the right elevator conveyance choice starts to take shape. For instance, for a two or three stop elevator, traction can be used but is highly impractical. There is simply no valid benefit for a traction elevator at that height. Likewise, an above-ground or holeless hydraulic elevator maybe less expensive, but impractical terms the limit is less than 30 feet. Also keep in mind that just because you can, does not mean you should. There are massive in-ground single stage hydraulic jacks. But, at the upper end it can get expensive, not only for the jack, but for drilling to nearly China.
So with all that said, hopefully you have a better understanding of the various ways an elevator moves and can start making clearer decisions on which should be employed in your next project whether you use Modular Elevator Manufacturing or not. If you would like a deeper conversation about what would be the best for your project, give us a call or get a fast track number by clicking the button below. We are looking forward to speaking with you.
By the way here is that fun video about the movies and elevators I promised click here.