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How do they go up the hill, and what keeps them from falling backwards? |
Roller coasters weigh on average anywhere between 1,200 and 4,000 pounds per car. That's before anyone is even in the car! With all that weight, how do you suppose a whole train of cars full of people is pulled up the lift hill? Actually, it's quite simple. Generally on a wood coaster, each car will have a clutch or "dog" assembly mounted underneath the rear of the car in the center. The dual-function of this dog assembly is to both engage the car onto the lift chain, which speeds it up the hill, and it also serves as an anti-roll back device, which would engage into a stationary ratchet on the lift hill in the event that the lift chain should stop. |
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| In the photo below, Harry from Morey's Piers in New Jersey is demonstrating for you what the anti-roll back dog looks like. You are looking at the rear underside of the coaster car. This particular train has dual anti-roll backs, as indicated by the "A" These two devices are made of cast steel, because it needs to be able to support the weight of the full train. This is what you hear clicking as you go up the coaster lift hill. The dog hangs down and bounces on the ratchet, as indicated by the "C" in the third photo. | In this next photo below, Harry is showing us the chain dog, as indicated by "B,"which is what engages the train to the lift chain as it begins it's ascension up the hill. Most coaster trains will have dogs on all but one of the cars, but usually only one dog on a train will carry the entire weight of the train up the hill. The system is designed to catch the first available dog as the train slows to match the speed of the lift chain, to make the connection less abrupt on the riders and easier on the equipment. The chain dog is solid steel, one inch thick by about 2-3 inches wide. |
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| Below is a diagram of a section of a coaster lift hill. "C" indicates the steel anti-roll back ratchets which are bolted directly to the lift structure in a way that would guarantee complete support of the entire load if the train should stop on the hill for any number of reasons ("E" in below photo). The dog, as it bounces its way up the lift, would slip backwards into this toothed ratchet, and would then be locked into place, preventing the weight of the train from overpowering the dynamics of the drive system and reversing down the hill. The "D" indicates the actual lift chain barrels, which is what part "B" in the above photo would mate with on the lift. As you know, the lift chain is the only active propulsion a roller coaster has. The rest is all gravity pulling you around the track! | |
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