Top Thrill Dragsters Launch System

Wednesday, April 21, 2004 10:18 AM
Hey guys, and gals. I am writing my freshman paper, and I need some good websites on the mechanics of TTD's launching system. If anyone knows any, please, let me know. Thanks!
Wednesday, April 21, 2004 10:23 AM
Virtual Midway has some stuff. Mainly Pics.(

RCDB is always a good bet. (

And don't forget good ol' Google. ( )

Wednesday, April 21, 2004 10:30 AM
Try this:
Friday, April 23, 2004 10:14 AM
Thanks guys, any others? I need all of the resources that I can get.
Friday, April 23, 2004 12:21 PM
Although I'm sure it's no nore detailed than what you have, if you go to this page and scroll to the bottom, the part4.wmv is entirely about Dragster.

It has Monty Jasper talking about some of the safety systems on Dragster.

Friday, April 23, 2004 12:27 PM
from those pictures, it shows the sled is in the back of the car, does it slide underneath all the way to the back?
Friday, April 23, 2004 2:50 PM
The sled actually "attaches" to the train from underneath...not behind. It slides below from the front and then electricity is used to bring a pin down from the bottom of the third car. The train then rolls back a few inches so as to secure the pin in a slot on the sled.

I'm guessing the only reason for showing the sled behind the train in the patent drawings is to keep things simple and easy to understand.

Friday, April 23, 2004 8:33 PM
To expand on what James just of these days I'll pull these materials together and Walt can add them to his feature over at Virtual Midway...

The sled engages the train at or about the fourth axle (er...I think that's right...). That is actually pretty near the center of the train. the launch sequence is something like this...

a) The train is rolled up to the launching point by the advancing wheels. The sled may or may not be in position.

b) The sled is moved into position if it isn't already.

c) A spring-loaded dog, similar to a chain dog is electrically dropped into the slot in the sled.

d) The advancing wheel assembly is dropped slightly so that it disengages from the train. Since the train is pointing uphill, this causes the train to roll back until the pin jams tight against the back of the slot in the sled.

e) The brakes are dropped

f) The electrical current holding the pin down is cut

g) The train is launched.

The reason for using a spring-loaded pin is pretty simple: When the train gets to the end of the launch, it has to disengage cleanly, which it will do by simply over-running the sled. If the launch should fail, though, Bad Things™ would happen if the train were to roll back down the tower and slam into the sled at 120 MPH. So once the train disengages from the sled, the dog is held fully retracted by some means (I am guessing a spring...) so that if the train rolls back, it won't be hanging down to engage the slot in the sled.

--Dave Althoff, Jr.

Saturday, April 24, 2004 12:44 AM

The catch car dog is an electro-magnetic system. There is a permanent magnet wrapped in a wire coil on either side of the catch car dog at the back of the 3rd car. The permanent magnets hold the catch car dog in the up position. There are 2 black patches on the top of the catch car track at the launch position just before the first pair of acceleration brakes. These patches are electrical contacts. When the launch operator presses the launch buttons, a current is sent from those patches and jumps to the wire coil around the magnet. This produces an opposing magnetic field to the permanent magnets and allows the catch car dog to drop under its own weight.

Once the train leaves the launch position, the current is no longer flowing in the wire coil and the permanent magnets reattract the catch car dog to its up position as soon as the catch car enters its brakes and disengages from the train in the 9th piece of the launch track. *** Edited 4/24/2004 4:47:31 AM UTC by Purdue University Engineer***

Saturday, April 24, 2004 2:54 PM
Sounds like, as usual, Intamin did things the complicated way...

--Dave Althoff, Jr.

Saturday, April 24, 2004 5:54 PM
Or the incredibly safe, efficient way.
Saturday, April 24, 2004 10:30 PM
Safe? Sure. Efficient? Irrelevant. Elegant? No.

-Rollerhammer (University of Illinois at Urbana-Champaign Mechanical Engineer)

Saturday, April 24, 2004 10:59 PM - Engineering news, engineering information and engineering jobs for engineering professionals


Sunday, April 25, 2004 6:13 PM
Sounds safer than just a spring as springs can brake and then the catch dog would hang down. Sounds like a well thought out design.

I actually wondered about a rollback catching the sled. I just thought that the sled went past the point where the catch dog lost contact with it and waited for the train to clear the top before returning to the start of the launch.

Sunday, April 25, 2004 11:44 PM
The sled does not move to any position where the train can't catch it. It just slams to a stop on the brakes at the end of the launch track, and the train over-runs it. Which is why it is necessary to have a means of retracting the dog on the train...on almost any coaster, that dog is an overrunning clutch. The drive mechanism (usually a chain) can push it forward, but can't pull it backward. Likewise, if the train moves forward over the drive unit, it will just disengage. If it tries to go backward, it will catch.

The Schwarzkopf shuttle loops have a similar setup, where the pusher plate drops electrically, and is raised by a counterweight when the train overruns the pusher.

--Dave Althoff, Jr.


You must be logged in to post

POP Forums - ©2018, POP World Media, LLC