Everyone wants faster. Many especially are obsessed with a faster car, but that is just the tip of the iceberg. Faster cars. Faster computers. Faster internet. But it really doesn’t work that way with elevators. For most low to mid-rise applications only 100 to 200 feet per minute (fpm) is desirable and for good reason. Any speed above 200 fpm would most likely never be hit in most applications below 10 stories and so wanting more speed would be just a waste.
To explain further, higher speeds in most hydraulic elevators are never obtained because elevators do not launch like rockets and have to stop in relatively short distances. The rate the elevator takes off at is called the jerk rate (please insert joke here) and how fast it reaches top speed is called acceleration. Acceleration and Jerk (rate of change of acceleration) are human comfort considerations that must be taken into account when looking at elevator speed. The practical limits (for math geeks) are 4 ft/sec^2 acceleration and 8 ft/sec^3 for jerk. If you are a math nerd, or you’re wanting to test out your math skills, this is a good place to start. But take it from me, fastest speeds in most elevators are never reached.
Even at the regular rate of travel between 100 to 200 fpm if the elevator took off too fast the occupants would be thrown to the floor like a character in a Loonie Tunes cartoon (the elevator fun starts at 2:06 in). Well…maybe the cartoon is a bit of an exaggeration.
So then if this is pretty common knowledge in the elevator world, why are elevator companies like MEM (Modular Elevator Manufacturing) asked to quote unbelievable rates of travel for even two-story buildings, sometimes five-times the proper speed? Two reasons. One is an honest oversight and the other seemingly more insidious.
Let’s look at honest reasons first. Completed project specifications or spec sheets are filled with tons of information. Like the Dictionary of Architecture & Construction says a specification sheet is, “a written document describing in detail the scope of work, materials to be used, methods of installation, and quality of workmanship for a parcel of work to be placed under contract; usually utilized in conjunction with working (contract) drawings in building construction.” That is a lot of information that has to be captured, updated and controlled.
So when it comes to any building project it is a mammoth effort and elevators are often held separately with elevator providers pulling the info together to be inserted. That means that there is sometimes a lack of direct oversight early in the process regarding the elevator. Also, the desired specs out of need and convenience have been largely copied and pasted from another source. The other honest mistake is when a company has had several projects of similar height or elevator travel. They feel the specifications can simply be copied and reused. Changes and updates are always meant to be completed, but sometimes the elevator is missed and one or two floors of travel can mean significant changes. These kinds of “whoops” can happen, but the mistake is usually caught somewhere in the process. Countless times we have had to get clarification when the overall speed does not align with the project. We call and the correction is made.
Now for the more insidious reason aspects of specifications are way out of whack regarding speed. Sometimes when asked for information on pricing, big elevator companies use the opportunity to push certain products and features; right now they are currently promoting traction as apposed to hydraulic elevators. A more cynical perspective is that over the long-haul the maintenance of a traction unit is twice to three times more costly and therefore more profitable for them. This can lead to big elevator companies suggesting products that absolutely make no sense. I have personally had conversations with multiple building owners and project managers of two and three-story building projects that were sold on the idea they needed a traction unit for more speed. In reality they needed no more than a simple hydraulic elevator with 150 fpm travel speed. The initial investment of going hydraulic was less and so were the legacy costs of maintenance.
So I guess my old Latin teacher was right “Caveat emptor” ~ Buyer beware. It is as true today as when it was first uttered.
If speed is still a concern, but you are thinking more about the speed of the overall construction process there is only one real choice in elevator that can move your along faster and that is a modular elevator from MEM. Contact Hugo Beltran at hbeltran@tlshield.com or call him at 800-755-9359. He would be glad to talk to you about the speed of elevators.