Thursday, April 18, 2002 5:03 PM
Has a chain dog ever actualy saved a coaster before?
At least I dont call a vertical loop a "loopdie-loop"!
Thursday, April 18, 2002 5:13 PM
Every time for what ever reason the chain lift loses power, the anti rollback, aka chain dog, keeps the train from flying back into the station. It happens more than you think.
Thursday, April 18, 2002 5:32 PM
The clickety-clank you hear while going up the lift is the chain- dog which keeps you from rolling back down the lift, also i beleive there are chain dogs on each car.
Thursday, April 18, 2002 5:43 PM
You guys are thinking of Anti Rollbacks. A chain dog is the part of the coaster train that engages the chain and allows it to be pulled up the lift.
Does CCI know how to make a bad coaster?
Thursday, April 18, 2002 5:45 PM
If you consider a chain dog "saving" a coaster being the same thing as the actual purpose of a chain dog, which is to bring the train to the top of the lift, then yes, it happens every day.
Quoth the Jaguar...."Check"
*** This post was edited by Spacecase8310 on 4/18/2002. ***
Thursday, April 18, 2002 7:12 PM
I've seen the chain dog and anti rollbacks on TV for quick shots, but does anyone have any close up pictures of either of them?
"This time I think ... I think it's ... it's going to work!" - Dr.Bruce Banner
Thursday, April 18, 2002 7:20 PM
Despite what a lot of people think, the chain dog does not prevent a train from rolling back. Anti-rollback latches do that. The chain dog's job is to basically 'grip' the chain so the train can move up the lift.
Thursday, April 18, 2002 8:19 PM
To add to what Sean just said...let's take a typical PTC car as an example. The dogs are more visible on Arrow trains, but Arrow does strange things like using only two sets of dogs per train, etc.
PTC puts a cast assembly at the back of each car, this casting has three channels in it and a single axle running through it. At the center of this casting, there is a long steel finger with a curved notch on the end. This is the chain clutch. It can move forward over a roller chain, but not backward, and this allows the chain to pull the train to the top of the lift; it also enables a clean release at the top. The two outboard channels contain fingers that hang down and catch the sawtooth on the outer edges of the chain guide. These are the anti-rollback dogs and they prevent the train from rolling backwards down the hill. On most coasters, if the lift motor were to stop, the weight of the train would pull the chain backwards down the hill if it weren't for the anti-rollback dogs. Also, if the chain breaks, the chain slides backwards out from under the train, as the chain clutch will allow it to go freely just as it does when the train goes over the crest of the lift.
Some coasters add another dog, a "chain safety dog" on the lift to prevent the chain from moving backward and piling up at the bottom of the lift. On PKI's Vortex
this is the noisy thing you can hear about halfway up the lift.
I may have some pictures around here someplace; if not, you might check and see if there are any photos of chain clutches on www.coasterquest.com .
--Dave Althoff, Jr.
BATWING FAN SFA
Friday, April 19, 2002 7:21 AM
RideMan beat me to it.
Friday, April 19, 2002 9:43 AM
I think that the best visual of an anti-rollback device was on Demon at SFGA. while standing in line, you could see under the cars. it was a long piece of metal that ran parallel to the car and the track. it attached to the car on a rod that stuck through the middle of it. at the back end was a point that stuck downward that caught the sawteeth. you could see it flying up as it went over the crests of the sawteeth and slamming back down when it got the chance. it was really pretty cool and provided something to look at while waiting in line.
-Bob (formerly Coaster Jedi)
Knott's Berry Farm Cuba ~South Park
"Your proctologist called, he found your head!" ~Jerry "The King" Lawler
Friday, April 19, 2002 4:41 PM
Yes! I have saved many coasters! :)
Without the chaindog, you'd never get up the lifthill...