Lift hill weights on B&M's

Watching B&M's I noticed there're a couple of plates hung on chains at the bottom of the lift hills that seem to move as the train engages and disengages the lift. Anyone know in more detail what is going on?

I always thought it was to keep proper tension on the chain.

Those are the counter weights for the lift that help to even things out, much like an elevator counter weight.

Neuski is right, it's just to keep tension on the chain. The way I understand it, there's a little slack, and the ability for it to give a little so that there isn't a "snap" on it when the train first engages it.

Just about all coasters have some sort of tension adjustment system on the chain, be it springs, weights, etc. If such a system was not there, the chain would very quickly snap from the coaster train catching on the chain.

The Mack wild mouse and water coaster (Journey to Atlantis at SWF) I've been on don't seem to have a good system for tension adjustment! When a car or boat gets on the lift, the chain lift bang around until the train start going up... The whole thing doesn't sound or look too good for the chain.

I've noticed that as well, especially on JTA. The one on Disaster Transport doesn't seem particularly affective either, and it's one of the bigger ones I've seen (it hangs through the ride's enclosure).

I believe they work on the same principal as the counter weights on a ski lift.
On older coasters, they have a gear attached to spings that take up slack and make adjustments, much like a derailuer (sp?) pulley on a multi-speed bike. *** Edited 5/31/2006 5:23:21 PM UTC by FLYINGSCOOTER***

Any pics specifically of what you're talking about?

http://www.delphion.com/details?pn=US04270459__

go to pic on right and enlarge. *** Edited 5/31/2006 6:12:30 PM UTC by FLYINGSCOOTER***

Gerstlauers also have that lack of tension in the chain.

I think since the cars weigh less than a B&M train, they don't need that kind of tension. *** Edited 5/31/2006 6:52:44 PM UTC by Cameraman***

Most Arrows have the "gear tensioning" system (or whatever you want to call it) system on thier lifts. It works well as long as the train engages the lift at roughly the same speed. If the train goes too fast while engaging the whole chain jerks and the gear/pulley system rocks back and forth.

The Gerstlauers have tension on the chain, they just dont have the plates to keep the chain in the trough. If the chain wasn't tense, it would rest in the trough, but because of the tensioning pistons on the main lower gear, it rises out. You can clearly see the whole gear move forward a good amount, and then relax back as a car engages the chain.

That's true you are correct.

Millennium Force's cable works in a very similar way. Link