16 replies to this topic

[KZ]

On sunday i noticed something very strange for the first time on newer poma detachable lifts. On Gold Coast Express at Squaw, instead of just tensioning the bulwheel of the lift, poma lifts tension by sliding the entire terminal. On these pictures you can clearly see this.

Here you can see that it clearly slides, and that the crossarms are never attached to the inside of the terminal


On the top terminal as well, it slides. You can see the pistons peaking through next to the far support.


On this one at squaw same thing, and you can also see the hydrolic rams attached to the crossarms. It seems like a system like this would be a lot harder to maintain because the hydrolics are pushing a lot more weight back. On goldcoast, there is also tensioning at the top terminal. I didnt check if headwall was the same, but i am guessing poma puts the hydrolics at both ends that way it doesnt have to push as hard.

This also shows why poma uses the attached hold down assembly instead of one mounted on a tower. With the terminal sliding, it would get all messed up if the hold down also moved. The system where the rope is pushed down may be used to get a bit more tension without having to move the terminals as far back


Here is Gold Coast at Squaw. Note the hydrolic pistons.

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[KZ]

Does anyone know why Poma does the tensioning like this?

[Kicking Horse]

cheaper would be my guess. eskimo does not have this sys

[liftmech]

Thoughts about this type of tension system:
-There's no difference in tension pressure required. The weight of the terminal is resting on the support crossarms, and does not affect the tension on the haul rope. That will remain the same.
-In some ways, this is a simpler setup- when the whole terminal moves, you can place the bullwheel wherever you want to inside and set up your deflection sheaves exactly as needed. The rope does not move around inside the terminal, so sheave loading remains constant.
-Also, the hoses for the hydraulic part and the wires for the carriage limit switch can be cut to a fixed length and do not need to be looped for carriage travel.
-Finally, without the need to have a long carriage platform inside the terminal, the overall terminal length can be shorter, allowing it to fit in tighter spaces such as the top of a peak or a narrow ledge on a mountainside.

-Jeff- are you sure that Eskimo is not set up this way? The terminals don't seem long enough to accomodate a standard internal carriage system, and I'm pretty sure I saw rams attached to the underside of the bottom terminal.

[Kicking Horse]

the whole terminal does not move like that. I will find out on Sunday what it uses and get a pic or two of it.

[Dr Frankenstein]

Another advantage : More compact terminals

[SkiBachelor]

I dunno, Leitner has some pretty compact terminals and their stations don't have a tension system like that. However, the picture below a bottom drive HSQ. I never saw the top of this.

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[edmontonguy]

i know for a fact that at least older doppelmayrs have the bull wheel tensioned. on many of the lifts where the bull wheel is open the tensionsing is clearly visable

[liftmech]

Poma may well be the only manufacturer to have this system. When you think about it though, it's just like a fixed-grip with a combined drive-and-tension terminal, i.e. Poma's Alpha drive or newer Riblets.

[KZ]

yes, but it is unique on hs lifts

[Allan]

YAN Bottom drive/tension terminals all move as a unit as well. Same with Muellers, altough a Mueller motor room is MUCH smaller than a detach :) Doppelmayr T-Bar's do too!

[SkiBachelor]

It just seems like it's a lot easier to maintain a hydrolic tension unit for a bullwheel rather than a hydrolic structure that moves (POMA terminal). This way also seems more complicated than it really has to be and money wasted.

[floridaskier]

I don't think it has a whole lot to do with terminal compactness. The newe CTEC Stealth 3's are very short, but they have an internal tension carriage.I think the size of the terminal depends on the detachable system and how long the chair takes to get up to line speed

[liftmech]

That's also true, although usually if you have a separate carriage assembly, you still need room inside the structure for carriage travel.

Quote

It just seems like it's a lot easier to maintain a hydrolic tension unit for a bullwheel rather than a hydrolic structure that moves (POMA terminal). This way also seems more complicated than it really has to be and money wasted.

There isn't any more to this type of carriage than to a traditional setup. The rams are mounted to the bottom of the terminal, usually attached to a strong frame member, while the pistons (the business end) are attached to the rear leg of the support structure. The same hydraulic unit is used regardless of which style of carriage is chosen- E-lift has the terminal we're discussing, while B-lift has a traditional carriage inside the return; both hydraulic units are identical.

[SkiBachelor]

Well, all I can say, it would sure suck a lot of someone stopped the lift right when you were about to step onto the ladder. Ouch, dang that would hurt like a moe pho.

[liftmech]

It's worse on a long lift with a counterweight. Old C-9 at Crystal was a good example- with a full line, stopping the lift made the carriage move several feet forward, then back. Unsuspecting lift ops would get clocked by the controls...

[Bill]

That would be funny to see since my locker partner was a dick and he was stationed on C-9. :)