Different Launch Question

Here is a question that to my knowledge has never really been answered and that I have always wondered about. We all know that the train is pulled by a "catch car" but my question is how does that attach and detach to the train and without some sort of severe damage to the cable. I would assume with magnets like everything else, but what do you guys think?

Go to:

http://www.coasterbuzz.com/forum.aspx?mode=thread&TopicID=37609

and read the 2 posts in the middle of the page by RideMan and myself.

Congratulations - good description of the launch sequence and the train dog engagement. The "patches" are little buss bars for the contactors on the train to get current.

I would have assumed it would be like a chain dog.

Keith - You are right the "dog" itself, mounted under the train looks for the most part like the chain dog on other roller coasters, its about 2" thick and pivots on a keyed shaft. It's just the mechanism that raises and lowers the unit that is different. The only time the unit (dog) is lowered is during the launch, all the rest of the time it's in the raised position.

All other generic coaster dogs are mounted on a shaft - side by side the anti-roll back dog - on a none keyed shaft so they move up and down at will (thus the clacking sound going up the lift)

Some coasters have 2 of these units per train - (2nd. car and 4th. car - Arrow) some have units on every car (PTC)

how does the train raise and lower the "dog" when it is not attached to the station?

Did you read the link I posted?

Wow, this is just OVER my head! lol. I understand it a little bit, but once you get into the electro magnet stuff, I'm down for the count. But I have always wondered this myself, so thank you for the answer! ;)

Jim Hancock said:
Keith - You are right the "dog" itself, mounted under the train looks for the most part like the chain dog on other roller coasters, its about 2" thick and pivots on a keyed shaft. It's just the mechanism that raises and lowers the unit that is different. The only time the unit (dog) is lowered is during the launch, all the rest of the time it's in the raised position.

All other generic coaster dogs are mounted on a shaft - side by side the anti-roll back dog - on a none keyed shaft so they move up and down at will (thus the clacking sound going up the lift)

Some coasters have 2 of these units per train - (2nd. car and 4th. car - Arrow) some have units on every car (PTC)

What he said. :)

~the clean up crew~

For those who are too lazy to click on the link

Rideman
To expand on what James just said...one 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.

and

Purdue University Engineer 4/24/2004 12:44:42 AM
Dave,

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***

Is there any video explaing the launching procedure od Hydraulic Launches?

P.S. Anyone know when Thrills and Chills is going to be on the Discovery Channel this year?