Tag Archives: maintenance

Rotting from the Inside Out – My Tooth, Your Elevator Jack

Candy CaneRecently, I bit down a bit too hard on a candy cane and I felt a strange sensation. My mouth was suddenly filled with a substance that was more like small gravel or sand than a candy cane.  I knew that gravel wasn’t on the list of ingredients, which meant something I dreaded much more:   One of my molars was broken and the pieces filled my mouth. Ouch!

I’m obsessive about my brushing and flossing, to the point of pride.  But, little did I know, deep in the recesses of my #18 molar, insidious forces were at work.  Painlessly and silently, tooth decay destroyed my dental pride from the inside out, and made a dent in my bank account.

A similar story can be told about elevators. They can look nice and shiny, with highly polished stainless steel hall calls, gleaming handrails and fancy glass interiors. They can be well cared for and brushed to a brilliant sheen, but the mechanisms that make them go up and down maybe rotting from the inside out, without anyone being the wiser. This is particularly true of older, in-ground jacks of hydraulic elevators because part of the elevator system is in the ground.  And far below the surface of the earth, they could be rotting with corrosion and rust.

In ground hydraulic jackPre-Nixon administration hydraulic jacks were made with a single metal bottom plate. With the jack exposed to the water in the ground, over time it can rust.  When it rusts all the way through the wall, the hydraulic oil begins to leak out.  If the jack loses oil all at once, the elevator car could fall.

Today’s jacks have a “double bottom” with the “second bottom” consisting of a bulkhead and orifice the slow any leakage and prevent a complete, sudden emptying of the jack.  In addition, the jack is contained in a sealed PVC liner, so there is no contact between the jack and elements that could rust it.

Should you worry about this if you are a building owner?  If you have a very old hydraulic elevator with an in ground jack, it is a concern.  If you have not had quality routine maintenance, it is a concern as well.  One of the telltale signs is that your oil level drops over time but it’s not visible in the pit buckets, which contain oil that leaks through the packing.  If oil is disappearing without a trace, it’s likely going into the ground.

Old Hydraulic Jack In Ground-01Another way to detect a leak is during annual inspections, which are required in most jurisdictions, and include a hydraulic system pressure test.  During this test, the hydraulic system of the elevator is tested to the maximum pressure the system can maintain. This maximum pressure is referred to as the relief pressure. The relief pressure can be up to 150% of the working pressure as per many state codes.

The working pressure is the pressure in the hydraulic system running at full speed and full weight capacity. During this annual pressure test, old and weak jacks plagued by rust and corrosion are susceptible to rupture. When it does, be glad it occurred during a test and not when passengers where along for the ride. It is always better to have a failure during a safety controlled test.

Just as I found out with my tooth, elevator repair can be expensive if it requires an entire jack replacement.  However, because safety is paramount, if a problem exists it must be discovered and repaired sooner rather than later. The bottom line, is despite my desire not to have dental work done, it was needed.  And if your aging jack is leaking, it’s much better to find out before the leak gets dangerous.  Then you can replace it on your time schedule instead of performing emergency surgery.

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A view from under the elevator car of an in-ground jack.

All About Elevator Jacks

A view from under the elevator car of an in-ground jack.
A view from under the elevator car of an in-ground jack with the piston extended.

When it comes to many elevator applications, especially for buildings between 2 and 5 stories, you will find a hydraulic jack is a common, yet crucial part of the system that drives the elevator up. As a matter of fact, approximately 70% of all elevators installed are hydraulic in nature and contain jacks.  The jacks are part of a system that includes hydraulic fluid, tanks, motors, and pumps with the jack being the final piece of the system.  So, understanding the basics of the elevator jack is crucial if you are considering buying a new elevator or modernizing the jacks in an existing elevator.

Depending on the system you have, the distance your elevator travels, and the space available, you have several options available. This article will explain the various types of jacks and the advantages and disadvantages associated with each.

  • Single Stage Holeless – Many times when new elevators are being placed, you can’t drill a hole in the bottom of the elevator pit or it is cost prohibitive to do so. Enter the holeless elevator jack. The most common jack used for short travel distances is the single-stage variety. A single stage means that it is one piston that goes up and down and it does not telescope when it reaches a certain height. These can be used for passenger or freight elevators.

The benefits of this type of jack (often called a twin-jack and used in tandem on either side of the elevator car) is that they are lighter and easier to put into place, are the most economical choice, and can be designed to carry very heavy loads. On the downside, because you are often dealing with two jacks, more adjustments must be made and it takes a bit more maintenance. Also, because the jacks commonly go on either side of the car, and there is no hole for the jacks to retreat in, there must be more space at the top of the hoistway above the car.

  • Single Stage In-Ground – This option is very common, especially when you can drill a hole in the bottom of the pit and want to travel multiple floors.  Because it does not telescope, the moving parts are limited and it is, therefore, reliable. It has also been around for a very long time as a solution and has a solid track record.

The good things about a single stage in-ground jack is that it is easy to install, fairly economical, especially for mid-rise projects, has a huge capacity, and maintenance is limited to one jack.   They also provide a very smooth ride. On the downside, the jack is in a hole. This can lead to leaks of hydraulic fluid into the underground water supply or contamination of the soil. Keep in mind that most of the contamination issues have been resolved with new technology and regulations. However, the threat remains: units can have a cracked PVC casing which can cause flooding of the pit and some fluid leakage. Also, old corroded sheaths that the jacks reside in need to be replaced, usually at a significant cost.   Also, the depth of the jack must be equal to the travel of the elevator car. This can mean an expensive, deep hole.

  • Telescopic Jacks (Holeless and In-Ground) – Telescopic jacks can have up to four pistons, each traveling inside each other. These are used when a more compact solution is needed for either freight or passenger elevators. Telescopic jacks going in-ground will reduce the depth of the hole required, but can sometimes be more costly in and of themselves.

The big plus is that there is a reduced drilling cost for an in-ground application and a higher travel distance than for holeless projects.  Also, the installation is usually fast as the jacks are compact and easy to handle. The disadvantages include the obvious; there are more moving parts, so initial set up may be more complicated (bleeding the jack completely, is required). Depending on overall travel distance, follower guides will be needed, requiring additional engineering. Long-term maintenance may be more costly, as well. Finally, there are simply more packing and seals due to multiple pistons.

Jack Travel-01

Each of the above jacks have their place and purpose depending on travel distance, but, as you can see in the chart, there is overlap based solely the height the elevator needs to go to. Other factors include price, the ability to drill, and even personal preference (some feel the ride is better in elevators that have an in-ground jack).

The best way to determine the optimal option for your building project is to contact an elevator consultant or an unbiased company that can provide any type of elevator.  They should welcome all your questions and be willing to break down all possibilities by price or other factors important to your project. If you would like to talk with us about elevator jacks, visit us here.

Safety: A Primary Concern of Modular

This traction elevator is one we toured at Elevator University.
Safety equipment is a must.

If you work in construction at all, you’re probably familiar with the the term “workplace falls”. Two past headlines concerning workplace falls involving elevator shafts include: “Worker Critical After Fall Down Elevator Shaft” and “Man Recuperates After Surviving Fall Down Elevator Shaft.” In the first example, the scaffolding the man was working on collapsed. He fell down the shaft and suffered two broken legs and a broken pelvis. He is expected to make a full recovery.

The second man didn’t fare as well. He was finishing concrete near an elevator opening when he lost his balance and fell 45 feet, breaking two vertebrae and ribs. Fortunately, he still has feeling in his legs and plans to walk again in the future. A third recent accident is under investigation, but it seems that it was an accidental fall down a hoistway as well, this time resulting in death.

Click for ways to be safe!

Elevator U Report: Maintenance – It’s Just Business

Recently, I sat in on a great discussion at Elevator U regarding elevator maintenance. Elevator U is an organization that has an annual gathering of elevator pe

Elevator U Final

rsonnel from colleges and universities around the country. The conference is a great opportunity to meet and greet some great folks in the elevator business and to learn a lot of valuable information through taking part in the various seminars and breakout sessions about the industry. One of the speakers this year was Dr. Clemense Ehoff, an accounting professor at Central Washington University. He is a published writer on information specific to the elevator industry, especially elevator maintenance.

During his presentation, Ehoff made a couple of important points about the vertical transportation industry that ought to be paid special attention by those that own buildings with elevators…Click for the whole report.

Elevator U: The Myth of Maintenance Teamwork

pierre-etienne-vachon-116891 (1)
Photo by Pierre-Etienne Vachon on Unsplash

Long-term planning for elevator maintenance takes cooperation from several parties and often is equated to teamwork. However, the idea that a team is always the solution to the problem often misses the bigger point. At the recent Elevator U conference we learned a lot about the various people that make elevator maintenance systems work but, surprisingly, the word team was never mentioned.

This is may be because when you hear the word “team,” you think of a group of individuals all dressed in the same uniform striving for victory, all pulling in the same direction. Even though everyone’s in-game goals may be different, victory for the team is always the objective, so they cast self-wants aside for the win.

Baseball is a great example of this.  See how elevators equates to baseball by clicking here.