Just a few years ago, the hype over electrified machinery was giving some pause to many machine makers and users, as they wondered if electromechanical actuators could top the power density of hydraulics. But that pause was short-lived, and most experts on both sides of the aisle agree hydraulics still has one big advantage — power density. Two recent examples come to mind.
Over the past few months, we’ve heard about a new market disruptor in the cylinder market — Rise Robotics’ new Beltdraulic design, which it says is faster and smoother than hydraulics. The company says it offers the power of hydraulics without the fluid and efficiency losses. As someone covering these technologies for 20 years, this is an amazing feat. Especially as efficiency loss is our biggest foe in the fluid power industry.
Rise Robotics’ Beltdraulic cylinder replaces hydraulics with an all-electric design.
I’ve seen the Rise design in person recently at a trade show and watched videos of it online. It’s an incredible design, but it still seems longer than many cylinders offering comparable forces. So, while I do see great potential in this design, I don’t see it completely displacing hydraulics anytime soon, especially where compact designs are required.
At Cedar Point in Sandusky, Ohio (not far from my hometown) we have one of the world’s most famous roller coasters. Originally, the Top Thrill Dragster shot riders 420 ft up a nearly completely vertical hill using a hydraulic launch at 120 mph. Throughout its many years, the hydraulic system needed maintenance and sometimes the ride was down for days at a time.
After a metal bracket came loose a few years ago and struck a rider waiting in line, the amusement park shut the ride down for evaluation and decided to reimagine the ride. It’s now called Top Thrill 2 and instead of a hydraulic launch, the ride uses linear synchronous motors to propel the train up the hill.
When I first learned about the engineering on Top Thrill Dragster more than 20 years ago, I was informed by Cedar Fair’s engineering team that the ride could only accomplish the incredible speeds and height with hydraulics — any electric motors would just be too large for the allotted space. Here, we could truly sing the praises of hydraulics — power density meant smaller pumps and motors could easily launch the train over the massive, nearly 90-degree hill.
So when I learned that the ride now uses LSMs, I was so impressed that they have come that far in the past 15 to 20 years. Imagine that they could now sling-shot 18 passengers up that hill!
The new Top Thrill 2, which replaced the hydraulically-powered Top Thrill Dragster, requires a triple launch up a second tower, to shoot riders of a massive 420 ft hill.
Image courtesy of Cedar Point.
Then I visited Cedar Point with my family for the first time since the ride opened. And I saw just exactly how they accomplish this feat. No, LSMs are not suddenly more powerful. It’s a triple-launch coaster, meaning that it is launched forward, partly up the hill, then rolls back up a vertical tower to gain the proper momentum and then, it flies up the 420 ft hill. Engineering marvels don’t need to apply, this is straight up physics at this point.
I’m not throwing shade on LSMs — they are incredibly fast motors that propel riders smoothly on many roller coasters, including Cedar Point’s Maverick, one of the best coasters out there. But they can’t stand up to the power density that hydraulics offer, and likely won’t anytime soon.
There are many detractors that say the maintenance issues were a big problem with the hydraulics on Top Thrill Dragster. And it did have its fair share. But from what I saw myself in person and what I’ve seen online, the new Top Thrill 2 still has many issues and is constantly shut down for maintenance. You can’t blame the hydraulics anymore.
Hydraulics biggest advantage is its power density.
I’ve always sung the praises of hydraulics. I love this industry and see the power and strength it provides to keep our world moving. There’s a place for all modes of power transmission in industry, and they can all get along (in fact, on Cedar Point’s newest coaster, Siren’s Curse, the vertical drop would not be possible without the combination of hydraulics, mechanical and electrical designs). If only we can say that about the rest of our world.
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