Why do Arrow Coasters do this?

Why do arrow coasters, when going up the hill, seem to have a "power surge" and slow down and speed up, all the way to the top? Unlike B&M's, Intamins, etc and so on?

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I have never had that experience on Demon or Shockwave at Six Flags Great America.

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I think you're referring to the timing of the lift hill so then the train does not leave that block if there is another train on the course. Actually, it's not just Arrow coasters that do that, on MF that slight increase of speed towards the top of the lift is indicating that the block is clear. If the block wasn't clear the lift would stop.

Hope I sort of clarified that fo ryou

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I think what he is refering to is when the train engages the lift it kinda jumps a little bit. It does that really bad on the Demon at PGA. I think its just over time either the chain stretches or the weight that keeps the slack of the chain is too heavy or too light. Im not totally sure but thats what im thinking.

only arrow i've truly noticed it on is Iron Dragon at CP and Top Gun at PKI. I know that iron dragons is waiting for the block to clear........if you watch carefully on Iron Dragon, if the train is late getting dispatched, it doesn't slow down, but if they are hitting interval, you get quite a slow down.

Yes, Top Gun at PKI does it all the time. It is indeed a blocking issue. Most, if not all the Arrows have these, some you notice, others you don't.

Maybe I'm wrong, but I think he's referring to the fact that, on older Arrows, all the way up the chain lift, the speed is uneven. Like the train will push forward and then slow down. Push forward and then slow down. All the way up the hill. I've noticed this too and i'll let some engineer explain it because I have no idea...

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I've experienced it definatly on Demon and Shockwave (SFGA), but the other Arrows that I've ridden I haven't ridden enough to tell. I don't know why it does it all the way up the lift, but that really big jerk at the bottom of the lift is because the train has some speed, then slows down to catch the lift, then speeds up to keep up with the lift. again, I don't know why it does it all the way up the lift, but it could just be from old age.

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If you're talking about a very steady pulsing all the way up the lift, then it's due to the fact that some Arrows use fixed speed motors. PGASFMW has the right idea. If I understand it properly, the motor is always running at a constant speed. The chain has some slack in it so between the train and the motor the slack moves around causing the train to pulse up the lift. With a variable speed motor (or trims before the bottom of the lift), the train will engage the lift at the chain speed and the pulsing shouldn't happen. This behavior screams for an explanation from RideMan.

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There is a tensioner on the chain on Arrow coasters. If you've ever been to Michigan's Adventure, you can watch it on the Corkscrew, because the mechanism is exposed under the lift. Basically, it's a big pulley on an arm that evens out the tension as the train engages and bounces slightly thereafter. Basically, it's there to keep tension on the chain so the train hooking on doesn't snap it.

Pretty much all chain lifts have tensioners. Different tensioners work on differtent principals. Most common are weights and pneumatic pressure. Some are just a mechanical slack adjustment. If the tensioner is well designed and maintained, you shouldn't get any surging. Unless it is extreme, surging isn't dangerous, just annoying.

Variable speeds are something else. As others have said to speed is adjusted to allow the block ahead to clear. Some coasters such as The Beast may come to an almost complete stop. Then when the block clears, they speed up again. They try to avoid a complete stop at any time since riders are likely to think that they are stuck.

What do you guys need me for on this thread? Looks to me like you've pretty well covered it!

Variable speed lifts: Iron Dragon is a good example...slow the lift until the next block is clear. Kennywood Jack Rabbit started doing this last season, too.

Surging due to action of chain tensioner: You see that a lot on the first lift of Adventure Express at Kings Island.

Another use for variable speed drives: Matching the chain speed to the train speed at lift engagement makes for smooth take-up. Otherwise you tend to get a train racing halfway up the lift and then catching the lift with a nasty jerk.

--Dave Althoff, Jr.

The reason B&M's dont do this is because it has a different tesioning system. Arrow's use the pulley system discussed earlier which bobs back and forth causing you to feel that the train is going back and forth. Interestingly the only Arrow I have ever felt do this is Canyon Blaster at the Adventuredome. I have seen the pulley bob back and forth on Rim Runner too another Arrow ride at the Adventuredome.

On B&M's they use a counterweight system. Its a system of weights that look kinda like the ones on your home gym. Intamin used this on Flashback at SFMM.

As for variable speed drives...I think they are very valuable as they allow smooth engagement which puts less wear on the chain.

Canyon Blaster, for example, doesnt have one. The train leaves the station at a pretty quick speed travelling a good distance before catching the chain. The result of this "overpowering" is that sometimes the train will "skip a dog" causing a loud bang (and downtime). This is basically the train not fully attatching (with both chain dogs) to the chain and falling back slightly so that the second dog attaches.

To combat this Disneyland has breaks before all three lifts on Big Thunder Mountain.

Nearly every Arrow coaster I've been on does this. I don't really mind it, It's just another charectoristic of Arrow's coasters (well, most of 'em), just like the loud chain lift. (Love that sound)

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