Dragster motor is HUGE compared to Xcelerator
Of course, my Dad used to schedule the production of machines that were held together by nuts and bolts the size of that engine, so I'm a little biased.
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I hear America screaming...
I'm afraid that you made a math error somewhere. A 6" pinion and a 72" (6') ring gear gives a 12:1 reduction ratio, not a 144:1. This brings the RPM way down, though 6000 RPM doesn't sound real high to me. My Honda is redlined at 6500.
I don't really know too much about hydraulics other than linear cylinders though, so I don't really know what is normal for this type of motor.
The yellow items are caps to protect the threads and keep trash out on the connectors for the hoses as previously suggested. For some reason these caps are almost always either yelow or blue.
(144:1 would give pinion speeds of 80,640 RPM, which is not merely ridiculous, but insane)
--Dave Althoff, Jr.
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- John
Dag, yo
Support Rob in the Great DDR Challenge!
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Jeff - Webmaster/Admin - CoasterBuzz.com - Sillynonsense.com
"The world rotates to The Ultra-Heavy Beat!" - KMFDM
The yellow plastic caps are covering the protruding hose connection which the hose will slide over and be clamped down. This to me appears would be the exit hose due to the way they connect. Then the inlet hoses would be bolted onto the outter sides of the motors with the steel elbow brackets. Though I could be wrong and it goes the other way, but either way there are two hose connections. You can clearly see the "bolt holes" on TTD's motors.
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Chris Tyson
Photographer
www.pkiunlimited.com
I think that some centirfuges that are reasonably large do turn at that sort of speed though. (These are the centrifuges that we don't want Iraq to have since they are useful for enriching Uranium.)
The first thing I thought is if the fluid goes in, how does it get out? Dave's hypothesis seems to make more sense, but upon further thought that drum looks a heck of a lot like the drive stystem on some of out hydraulic presses at work but with two sets of "modules." I am gonna have to take a pic when I go in monday and see if I may be right.
If thats the case it makes a lot of sense.
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Da Poodle
Coming in 2003-The Spawn Of Magnum!
*** This post was edited by MagnumForce 2/8/2003 1:11:38 AM ***
I see the other hoses now, and it looks to me like the side fitting (bolted flange) is probably the high-pressure side of the motor, as the back end is clamped. That arrangement is still consistent with the requirements of a cylinder for an axial piston arrangement, except that on first thought I would expect the pressure and return sides to be reversed. Never mind that until yesterday I'd never heard of any kind of piston-driven hydraulic motor... :)
--Dave Althoff, Jr.
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Da Poodle
Coming in 2003-The Spawn Of Magnum!
Liquids, including hydraulic fluid by nature are incompressible. We can use them for transferring energy by putting pressure on liquids, and then allow the pressure to be released on a device that transfers that energy into mechanical energy.
Accumulators and hoses and pumps, OH MY! The way the accumulators work has been described many times, but I’ll give my take on it. There are 4 sets of accumulators, each has 4 tubes. There are 3 tubes that sit on the ground that are connected at the end to the fourth, which sits on top of them. The bottom three tubes have pistons in them and are full of nitrogen one side of the piston. When the system charges, hydraulic fluid pushes on the piston, compressing the nitrogen. There is a fluid control unit on the end closest to the drum, and it is connected to the top tube. It controls where the fluid goes at any given point of the launch cycle.
There are three phases in each launch cycle. There is the charge, the holding, and the run phase. During the charge phase, the motor pumps hydraulic fluid into the accumulators via the fluid controller. The pump pushes the fluid into the accumulators till the system is at the pressure level that the PLC sets. The valves shut then the pump stops. Now the system is in the holding phase. During this period, no fluid is let in or out of the accumulators. When the train is set up for the launch, the third phase is soon to be underway. The 4 valves in the fluid control unit that allow the fluid to go to the motors through the small hoses open. The valves might not open all at once though. I’m thinking each fluid control unit opens 1 valve each simultaneously and waits say 5 milliseconds to open the rest. The reason I would do this, is to give a first burst of pressure less significant to make the entire launch system taut. When all the valves are opened, there will be less shock, reducing wear. Finally, when the system is ready to stop, the valves on the accumulators close.
I’ve been thinking about how this system works ever since I seen it for the first time. There are a bunch of relatively small blocks that hydraulic fluid goes into at one point, and out at another. Somehow they turn a large flow of hydraulic fluid into massive amounts of mechanical energy that turns a big drum quickly.
I’ve been comparing these motors to a torque converter, but now after much thought, I’ve been thinking of them like a hydro-electric turbine. They are a similar concept, but in the hydraulic motors case, a turbine makes more sense.
From the pictures I’ve seen, such as this and this. The smaller hoses that carry the fluid from the accumulators to the motors, connects at the top of each ‘block.’ There is also a large hose that connects the motors at the ends, to the pump/reservoir.
Here is a picture of my hydraulic fluid theory. Let me dissect it first, and explain. It is a simple picture, showing a cutaway of the motor. There is a small hole in the upper left corner of the top block. This is the high pressure line that extends the whole length of the motor. It connects to the small hose at the top of the block towards the middle. The line going down from the high pressure line feeds the turbine. There is one line for each turbine of the motor. There is 3 or more turbines for each motor. Next, there is the turbine. The fluid pushes down on the fins, spinning the axle counter-clockwise. The fluid goes down and around the turbine in a U shape exiting out. Finally there is the return line. This is larger providing a lower pressure place for the fluid to go. The return line goes the whole length of the block, exiting at the end to the large hose.
When the launch starts, the fluid pushes down on the fins with a lot of force. This causes the turbines to quickly start turning. Since the motors are small in size, like a turbo changer, they can turn extremely fast. Turbochargers are known to turn at 150,000 RPM. Getting the turbine motor to turn at 100,000 RPM with minimal risk of damage is not only possible, it’s actually practical in a hydraulic motor application.
Now that you have a bunch of motors capable of turning very fast, how are you going to convert this into the drum shaft? Planetary gearing was suggested, to be honest, it’s a very good way transferring huge amounts of mechanical energy. You have multiple planet gears contacting the sun gear at the same time. The teeth are the weak point of gears, and planetary have multiple times the number of teeth contacting each other. You can either have the planets turning the ring gear or the sun gear. I’ll just say the planets are turning the sun gears.
Finally, you have to figure out the gear ratio. I guess it has already been figured that the peak RPM of the drum is 560 RPM, so I’ll use that. Using peak values for the Drum and the motors, I came up with a formula. Y=R/560 Y is the drum ratio, R is the given motor RPM, and 560 is the drum RPM. If the peak value for the motor is 100,000 RPM, the ratio would have to be about 180:1, for 50,000 RPM the ratio would have to be about 90:1, and so on. If the ratio was 180:1 and you have TTD’s 32 motors putting out 1 ft. lb. of torque, the result would be 5760 ft. lb. of torque. If you had the same ratio and number of motors, but each motor putting out 2 ft. lb. of torque, that would equate to 11520 ft. lb. of torque. As you can see, this setup would release a HUGE amount of energy in a short period of time. That is exactly what Intamin was after when they designed this incredible system.
I would like to thank Seth Oakley for hosting my image, Dave Althoff, Jr. for the picture of the launch system test setup, and Jeff for the other pictures. Also I would like to thank Twistedrails.com and americacoasters.com for having great pictures. Finally I'd like to thank howstuffworks.com for all the great articles they have.
I hope you liked reading this, as it took me over 4 hours to complete.
-Marc Robertson
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Last 2002 public ride on MF's front row
:Edit: Minor paragraph structure editing, and link added
*** This post was edited by SteelMonsters 2/9/2003 10:28:22 AM ***
-Marc
The topic is titled: "Dragter motor is HUGE compared to Xcelerator" Hmmmmmm..............Isn't this kind of a VS. topic? I thought those topics were prohibited?
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YOUNGSTOWN 2010
The most obvious explanation is that each module contains a hydraulic motor, driving a planet gear housed inside the little round protrusion in the drive assembly, with the sun gear inside, right? It makes perfect sense. It doesn't explain how the motor assembly works, as that hose fitting can handle a lot of fluid and I am not certain that a vane-type motor can , but it is a logical explanation for the gearing.
Until you look closely at this photo. Yeah, that's the same photo that SteelMonsters Marc referenced in his most recent message.
Let us assume for the moment that in that photo, the large beige component is completely assembled to the red components. This makes sense as the whole assembly is being hoisted as a complete unit.
What I just noticed is that the bulges on the ring assembly are not aligned with the red modules. It does not appear that the center of the circular piece aligns with the spot where one would expect to find a motor shaft.
Does that mean anything? Hell, I don't know. :)
--Dave Althoff, Jr.
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Chris Tyson
Photographer
www.pkiunlimited.com
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If practice makes perfect but noone is perfect, then why practice.
Xcelerator and Dragster are in fact pulled at great speeds via a cable.
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Da Poodle
Coming in 2003-The Spawn Of Magnum!
A vane type motor can't handle the entire flow by themselves. The flow gets split up into about 4 or 5 different turbines in the heads. The turbine I drew is... well not very good.. it just shows the concept.
With the gearing, the axle appears to line up on the inter-most part of the of the beige disks that stick out. I'm thinking there is an intermediate gear from each unit, to the sun gear. It's hard to say. Here is another picture of TTD's hydraulic unit. From what I can see, there is a smaller gear attached the the motor unit's axle, then there is a larger gear that sits in the part by the head in the picture that you showed Dave. [BTW, I'm calling the unit with the hoses connecting to it, the 'head'] Then that intermediate gear is connected to another gear that connects the sun. Basicly just another step in the process.
Have fun picking apart the rest of my post. :) It's a straight forward concept, so I haven't have much of a chance to work out the bugs.
-Marc
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Last 2002 public ride on MF's front row
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