# Xcelerator Launch Mechanics

Saturday, December 21, 2002 6:04 PM
So I'm still trying to wrap my brain around the mechanicals of Xcelerator's launch...

I understand it in concept, but my question is this: where does the power come from? How is the cable reeled in so fast?

The ride op told me that while "there's hydraulic fluid in the tubes, it's powered my LIM magnets." He's wrong, right? I thought there weren't any magnets on this thing at all.

I thought I read somewhere that pressurived nitrogen is used somehow, but I could be wrong.

So anyway: what creates the power?

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Saturday, December 21, 2002 6:08 PM
If the ride was powered by LIM's, it wouldnt need Hydraulic fluid. Im pretty sure there are no magnets on this ride, and I heard it ws powered by hyrodraulic pressure.

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"Launching in 1,2,3..2..1"
-Wicked Twister Ride Op.

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Saturday, December 21, 2002 6:37 PM

This is how it works in very simple terms. The hydraulic system charges units called accumulators. These accumulators shoot out hydraulic fluid at an extremely high flow rate. This fluid then turns a hydraulic motor which in turn winds up the launch cable.

There are magnetic brakes on the trains. On the track are the brake fins. These retract out of the way for the launch, and when the car starts up the hill, they extend in case of a roll back.

Any other questions?

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Art, Art, Art, everyone wants it, some need it, most don't want to pay for it.

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Saturday, December 21, 2002 6:49 PM
Think of a locomotive... the steam pressure moves the piston on the front wheels and roatates the wheels... but of course, Xcelerator's launch is much faster.

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Jes
Jes's Roller Coasters DJ Jes
Six Flags Worlds Of Adventure 2002 Ride-Ops Crew (Have Fun Trying To Find Me!)

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Sunday, December 22, 2002 12:02 AM

Wouldn't a ride operator (rather than an attendent) know that the ride is hydraulic? Especially when the ride attendent is usually Mandy (enthusiast on Extreme rides 2002), a veteran employee, or a manager, or at least read the manual and took a test.

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Sunday, December 22, 2002 2:07 AM

Heres how it works-

There a 8 large shafts, 4 connected to each side of the mechanism. Liquid Nitrogen is stored in tanks that is released into these shafts which are heated. The heat causes the nitrogen to expand into a gaseous form with a huge force and large amount of pressure. They drive a piston forward to the other end of the shaft, forcing hydrolic fluid into lines which lead to a turbine. As the fluid is forced into the turbine, it spins it at an increadable amount of speed. The turbine is connected to a reel, which pulls the cable in during the launch. It's a very clever system, except that the freezing nitrogen on one side of a piston and hot hydrolic fluid on the other side is very bad for the metal between them, which causes it to crack. WHen Xcel goes down, its usually to repair a cracked piston head (they just pull out the whole pump and replace it).

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Sunday, December 22, 2002 4:32 AM
Well I dont know who to believe, but the launch according to ThePhantomLives and the magnetic brakes according to Coaster Art Guy makes sense to me, but whatever....

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"Launching in 1,2,3..2..1"
-Wicked Twister Ride Op.

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Sunday, December 22, 2002 7:30 AM

Hen Xcel goes down, its usually to repair a cracked piston head (they just pull out the whole pump and replace it).

When I was in California earlier this year, they used a crane to replace something behind the shop in the launch 'room'. It was a sort-of grey thing about four or five foot long and three foot tall - is this a pump like you described above?

How reliable is Xcelerator? I visited Knotts twice, and it was closed all day on the first and opened late a few days later. The woman in the shop was mumbling that it was down a lot, but of course that's just hearsay.

Regards, Marcus
Coaster Kingdom: Hydro Review

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Sunday, December 22, 2002 9:11 AM
So liquid nitrogen is converted into gaseous form which generates pressure which in turn forces hydraulic fluid against a turbine connected to a drum of some kind which reels in the cable... got it.

Is the nitrogen conversion instantaneous? When the ride op presses the 'Launch' button (over-simplification, I know), is the liquid nitrogen then released into the chamber and flashed into a gas? Or is the pressure accumulated over time, then allowed to release against the hydraulic fluid?

Just curious...

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Sunday, December 22, 2002 9:43 AM

I think its the second choice of your's, but I'm not sure. Anyways, as for Xcelerator's reliability, that lady was right (after all she's there 6 days a week), but its been open every day I've been this year, except maybe once. But of those days, the only day it was doing great on the reliability was the weekend after opening day, when it was still running 1 train. Usually, the ride goes down for a long time in the middle of the day, and just doesn't want to run. Its got the curse of the soap box racers. I really hope they fix the bugs out in Dragster (and eventually modify Xcelerator to be more reliable) otherwise A LOT of people will become very disappointed. The ride never really builds long lines (except at haunt), unless it opens up after a breakdown, then everyone rushes to ride. The line is usually only 20-45 minutes though, so you won't get MAD when it breaksdown. I think it will become a little more reliable over time, just like its sister perilous plunge, who's now pretty damn reliable (for an Intamin Prototype).

Hey, marcus. on hydro's revenge, can they control the splash size? perilous plunge doesn't use it because it always makes the ride go down, or crash into the rocks at the end of the ride (well that was more fiddling with the level of the water in the splashdown pool).

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Sunday, December 22, 2002 9:48 AM
I am not familiar with the mechanicals of the ride.

With that out of the way, let me explain how a certain hydraulic component works, which may clear up some confusion about this ride.

In general, hydraulic cylinders are limited in their operational speed by the amount of fluid pressure supplied by the hydraulic pump. Trouble is, if you want to do a launch, what you really want to do is move a whole lot of fluid very quickly in order to release energy very quickly. You could do this using a *huge* pump or a series of *huge* pumps, but that is an inefficient process. What you would prefer to do is something like what S&S does with their Space Shot rides. On those, air is pumped into a pressure tank, then on demand all of the air is let out so that a huge volume of air...far more than the compressors can supply...comes out of the pressure tank and into the shot cylinder.

This is all well and good, but hydraulic fluid is not compressible. This tends to make hydraulic systems safer (less likely to explode) than pneumatic systems, but it is a limiting feature of hydraulics. You can't pressurize a hydraulic cylinder and then fire it off at will.

What you *can* do is to pump hydraulic fluid into an accumulator. An accumulator is basically a hydraulic cylinder with a piston in the middle. The space between the piston and the bottom of the cylinder is filled with (inert) Nitrogen gas. The top of the cylinder is equipped with two valves. The hydraulic pump supplies fluid into one of the two valves, filling the top of the cylinder. This process pushes the piston to the bottom of the cylinder. The hydraulic fluid is not compressed, as it is not compressible, but the nitrogen gas in the bottom of the cylinder is compressed. Once the accumulator is full of fluid, the small filling valve is closed, and the larger gate valve is opened, causing the fluid contents of the accumulator to be forced out all at once by the piston, powered by the compressed nitrogen gas. Nitrogen is used because (unlike oxygen or compressed air) it is non-volatile and won't explode under high temperature and pressure.

Accumulators are also used in less exotic systems (such as simulator motion bases) to maintain system pressure in situations where loads are non-continuous and sometimes exceed the pump capacity. A bit like the pressure tanks used in pneumatic systems.

--Dave Althoff, Jr.

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Sunday, December 22, 2002 9:53 AM

on hydro's revenge, can they control the splash size? perilous plunge doesn't use it because it always makes the ride go down, or crash into the rocks at the end of the ride (well that was more fiddling with the level of the water in the splashdown pool).

Yes, they can.

That said, when I was at Knott's, I noted that the mechanics of Hydro when compared to Perilous Plunge are more in-line with that of a normal Giant Splash ride.

For example, I noted that on Perilous Plunge there was a set of tyres to stop the boat under the bridge before going into the turnaround. When I was there it seemed to be causing downtime as there were a few maintenance guys in waders replacing a wheel.

Hydro doesn't have these (although it does only run a single boat).

That said, Hydro seems a much faster ride both on the turnaround at the top and at the splashdown. Normally the splashdown slows the boat on Giant Splashes, but on Hydro (presumably because the boat is on rails) the boat goes speeding way under the bridge and doesn't really stop until it dips into the water on the turnaround.

I can see that Hydro could do the same as Perilous Plunge. I have seen this photo before - has it done this a few times before?

Regards, Marcus
Coaster Kingdom: Tidal Wave Review

*** This post was edited by Marcus Sheen on 12/22/2002. ***

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Sunday, December 22, 2002 10:02 AM
RideMan, I am just curious, how do you know so much information about so many different topics?

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Rob

"Some people spend an entire LIFETIME wondering if they made a DIFFERENCE. The MARINES don't have that problem." -President Reagan 1985

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Sunday, December 22, 2002 10:02 AM

This thread looks sufficiently hijacked now, but when Perilous Plunge was first testing, it made a splash that hit the arcade building! I have never seen it hit the rocks like that (thankfully), I doubt it has happened to many times, and I particularly doubt it has happened anytime recently.

I'd really like to go on Hydro, as I never got to ride Perilous Plunge before the new restraints. :(

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Sunday, December 22, 2002 11:11 AM
Okay.... no offense but how does that have anything to do with Xccelerator's launch mechanics?

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"Launching in 1,2,3..2..1"
-Wicked Twister Ride Op.

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Sunday, December 22, 2002 3:34 PM

Hey, I don' claim to have first hand knowledge of the launch mechanism. However being an engineer, and seeing the pictures of the hydraulic units, I happen to know what they are and what they do.

The easiest way to do this is with a hydraulic motor attached to a pulley/spool system. The hydraulic motor turns the spool with the launch cable and launch mechanism attached to it. When the mechanism hits sensors in the track, the PLC (programmble logic controller) turns off the hydraulic valve that is activating the hydraulic motor that is moving the cable and cars. The hydraulic pump(s) then recharges the accumulators for the next launch.

Accumulators can be made any size, and they are usually filled with nitrogen. The nitrogen is compressed when the hydraulic fluid enters the accumulator. When the valve opens this sends the fluid at a extremely high flow rate for a short burst. The more accumulators, the longer you can run at that flow.

Think of it this way, without accumulators, you would need a pump system that would be able to produce that type of flow on demand. In this case the pump system would need to be at least 10 times the size of what it is now. After the brief period of the launch, the hydraulic system recharges the accumulators. Thus, the pump(s) only need to be large enough to recharge the system in X amount of time.

Again not claiming to be an expert, but I have used and designed enough systems to be fairly sure of how it works.

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Art, Art, Art, everyone wants it, some need it, most don't want to pay for it.

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Sunday, December 22, 2002 5:21 PM
Okay, Art, it sounds like we agree on the most basic principle...that of using accumulators to get the kind of flow rate necessary for a launch. You've taken it a step further...now we have the accumulators powering a hydraulic motor...in this case a rotary motor of some kind...that is going to pull a wire rope down the launch track; that wire rope is going to pull a launch sled which I hope pushes against either the back of the train, or even more logically works a bit like the Millennium Force lift sled...pulling against a chain clutch on the bottom of the train. That way once the train is running faster than the launch sled, it will simply disengage. That will happen when the launch sled reaches the end of the launch track and starts braking for its reset.

(Set off as more speculative than real...)
You know, I'd think that the sort of ideal way to work this would be to have a continuous loop with two coach pushers on it. My thought is that by doing it that way, the launch cable would not need to be reset...it would self-reset because the stopping position for one pusher would put the other pusher in the ready position (Schwarzkopf did this with the dual-chain lift mechanism on the Doppel Loopingbahn). Even better, the system could be equipped with 'extra' accumulators so that one system could be charging even as the other system launches a train. That way, the delay between launches could be minimized.

The other feature of this system is kind of neat. And this part I'm reasonably sure of. :) The train is equipped with high-power magnets like those used on the drop rides (remember those?). In this case, the copper fins are mounted on the track and attached to a series of hydraulic or pneumatic cylinders. Prox switches along the track are used to monitor the train's progress, and as the train passes each of the brake fins, the fin is raised into the active position. That system substitutes for the conventional anti-rollback system. The idea is that the brake fins are completely clear of the train as it is launched, but once the train passes, the fin pops up so that if the train comes back for some reason, its brakes will function. That way even if the train stalls out at the top of the highest point of the ride and then rolls backward, it won't come crashing into the station at top speed, a Bad Thing™ indeed.

--Dave Althoff, Jr.

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Monday, December 23, 2002 2:09 AM

For the German-speaking onces among you, you can find a detailled and illustrated explanation of the launch mechanics on a German site..

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Dutch Coastin' :: European coasters, thrills and theming!

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