Skilifts.org / SORT Forum

floridaskier, on Mar 11 2005, 07:50 PM, said:

A flat tire? A siezed compression roller? Too many fat people in the chair overloaded the PTO :P ? I'd like to see something like that trip a counter fault but whatever.

Duck, on Mar 10 2005, 07:14 PM, said:

Neat idea! It would be very hard to sync the linear motor w/ the haul rope at all the different speeds. The tricky thing would be when the lift is ramping up or down. Man, the termainals would be quiet, though!

Mike, on Mar 11 2005, 08:25 PM, said:

Can the too many fat people thing really cuz that issue?

Mike, on Mar 11 2005, 11:30 PM, said:

With the right control system and programmer, I don't think it would be too difficult. An encoder on the bullwheel and careful programming would certainly take care of it. You're right, the terminal would be very quiet, and have no moving parts.

The main reason I dismissed my idea as impractical was safety. In the event of an e-stop or control failure, you can't as easily lock down the carrier positions. On a conventional detachable the tires in the terminal are all driven off the rope itself via the PTO. But in my system, unless you have some kind of robust mechanical drop-brake that is going to guarentee the carriers can decelerate and stop at any point in the terminal... Yucky.

Actually, (thinking out loud) I supose the simple thing to do would have a whole bunch of LIDB (linear inductive dynamic brakes) which are normally supported in a "clear" position (pneumatic? electromagnetic?) when everything is A-OK. In the event of a fault, they drop down, decelerating each chair. On power-up the control system could take a look at where each chair is and make sure it moves to the right position on startup.

But again, that's my laziness as a mechanical guy passing everything off to the programmers. :P

-Iain

Kicking Horse, on Mar 11 2005, 08:49 PM, said:

It shouldn't... Accelerating more weight takes more force but the lift should be engineered so there is more than enough available torque. I've seen chairs get delayed at the load area when people hold the chair back. Either the tire slips on the traction plate or a belt slips.

Duck, on Mar 11 2005, 10:16 PM, said:

As you heard, Quicksilver at breck has seven motors in the return terminal that move the chairs. There are quite a bit of electronics and software to match the speed of the motors to the haul rope but it does work. I'm sure the same principal can be made to work w/ linear induction. The speeds have to be matched damn close so the grip doesn't wear every time it attaches and detaches from the haul rope.

That's something I hadn't considered, but it makes sense. For the number of times a chair engages/disengages the rope in a given operating day, yeah, I guess you wouldn't want it rubbing at all on the rope!

I assume grips usually wear out faster than the haul rope. Or I guess that's what the guys who work on these all day hope? :)

-Iain

That depends upon a variety of factors. A rope on a Riblet usually is replaced before the clips are, due to the reval of the core every time you move a clip. On a detachable quad, however, the rope can last a long time because the grips never stay in one place and are not attached going around the bullwheel.

Back on topic- matching grips speed to rope speed at the point of attach or detach is pretty important, and it can be off if your belt sheaves are worn, your belts are worn, your belt sheaves are the incorrect ratio to one another, and such. We replaced the entire terminals' worh of belt sheaves on B and E a few years ago because they were worn. That made a large difference. Smoother accel/decel, better speed match.

Duck, on Mar 10 2005, 08:14 PM, said:

As an embedded software developer, I'd love to work on a system like that! However I think that in reality it wouldn't be too practical. The LIMs generate a lot of heat, and are surprising power hungry.

Stopping the carriers in the terminals in the event of an E-Stop (or power outage) can be accomplished simply by having the carriers travel slightly up-hill through the stations. Add a (passive) magnetic anti-rollback system (like Intamin use on their roller-coasters), and everything is good.

Cameron.

The LIDB which I refered to is what Intamin uses, theirs from ProLIM (an American company, Magnetar, offers a similar product). It'd be best to have the track in the station flat, as a dynamic brake like that can never fully stop a moving vehicle (the braking force is directly proportional to the speed at which the two elements (magnet and fin) are moving relative to one another). As the vehicle slows, the braking force is reduced. Intamin fully stops their trains on coasters having those by having them bump up against the kick tire that brings the train into the next block.

(Totally off topic, but the scarriest rides I've ever had were back in 99 when Superman RoS @ Darien opened. It ran so fast that summer. I remember on the hottest days, watching the trains skid further and further through the brake run, each train pulling a block violation and requiring a control system reset on every cycle. They were coming within a car length of colision. Just awesome. :))

A good example of the dynamic brake not being able to fully stop a vehicle is Intamin's Giant Drops, which, during deceleration, reach a constant creep speed at the end of the cycle for landing.

The heat thing I think would be fine, becuase there are a lot of Intamin/Premier coasters out there with linear motors on them that operate all summer long. The winter would have the benefit of offering natural cooling. ;)

But the power hungry issue you're right on. The surge loading from LIM based coasters is what drove Intamin to develop their hydraulic launch system (Xcelerator, TTD, Kanonen, etc..)

Actually, now that I re-read what you said, did you mean to use a magnetically-decoupled antirollback (so fowrard motion lifts the dog, preventing noise/wear, and during an underspeed/stop/rollback, the dog kicks into the sawtooth, stopping the carrier)?

-Iain

Duck, on Mar 14 2005, 08:12 PM, said:

One major difference is that the costers launch every couple minutes whereas the lift will have to deal with a carrier every 6 seconds or so. The carriers are quite a bit lighter than a coster but they aren't light (Poma's 6 packs are around 1200 pounds empty!).

Bombardier/UTDC's ICTS (Scarborough RT, Vancouver Skytrain, Detroit PeopleMover, JFK AirTrain, Kuala Lumpur LRT, etc.) use bogie-mounted single-faced LIM's engaging a fixed reaction plate in the guideway. They run all day/every day with relativley large loads. I don't think heat will be too much of a concern.

 skytrain_car_diagram.gif (97.98K)
Number of downloads: 22

-Iain

Duck, on Mar 14 2005, 09:12 PM, said:

Oh right .. but I was referring to Intamin's anti-rollback on the lift-hill .. the movement of the train up the lift generate the magnetic force which holds the roll-back dogs up and away from the lift. When the lift stops, so does the force, which allows the dogs to drop and hold the train in place. This is why the Intamin lifts (even their chain lifts) are completely silent (but make quite a loud clang when they stop ..). It is similar technology that is used for the magnetic brakes.

A similar system could be used for the chairs in the terminal .. Add an anti-rollback dog that is held out of the way as the chair is moved through the terminal by the LIMs .. but in the case of an e-stop, the LIMs shut off and the carriers stop .. dog drops down and hold them in place.

As for the heat .. I know that some of the Intamin Impulse coasters do have heat problems in the height of summer .. and occasionally have to be shut down for an hour or so to cool off. These rides use the LIMs to park the train at the end of each cycle, so they get quite a work out.

Cameron.

Well, in a low-speed, low-load application like this, I still don't think heat would be an issue. But you're right, the Impulses do get really hot (in certain seats, you can feel the heat blowing down on you from the big centrifugal blowers up above).

All this aside, tire driven turnarounds look easier to work on, wheras chain systems are less likely to fail in the first place. Of course, I've never riden a system that has chain cadencing, so it's an assumption (probably wrong) on my part.

And, shoot, I just noticed your name in your sig. How's it going man? :)

-Iain (from r.r-c!)
This post has been edited by Duck: 15 March 2005 - 09:19 AM

Chain systems have their failure points as well, usually in the chain itself as well as the transmission from the bullwheel. I don't know how exactly Doppelmayr powers their chains, but Poma has three to four drivelines and two other chains between the bullwheel and the conveying chain. The second chain (a single 24.5mm or 1" roller chain) is most susceptible simply because it is the smallest component.

The older Doppelmayr's are pretty similar. Gearboxes, chains, and driveshafts. (and belts if you want to include the accel/decel drive.)

Duck, on Mar 15 2005, 11:14 AM, said:

Someone on a ski-lift forum has recognized me from a roller-coaster forum, I think I've reached a new level of nerddom! :)

Things are doing fine .. Just got back from three terrific days at Whistler!

Cameron.

Cameron, on Mar 18 2005, 09:20 AM, said:

Hi Cameron and Iain, the is Pete from rec.roller-coaster!

Love your LIM idea Iain, but I do think the cost of running a lift with LIMs would not make it practical. Much cheaper to have a PTO turn some tires than paying the electric bill on LIMs in the terminal.

Nice to see a few coaster enthusiasts also into winter sports!

Pete Babic?! This is insane. :)

You're right - the cost of the electricity would also make it prohibitive. Although the cost of electricity might be offset by the absolutely reduced maintenence. :)

-Iain