22 replies to this topic

[highspeedquad]

When I was skiing at Breck I noticed that at the top terminal the stop gate was a string, so that if a skier accidentaly rode around the bullwheel they would hit the string. However, in the pictures here and in my memory there seems to be an electric eye serving as the stop gate. Why would they change it to a string? Is there any things a string has that the eye doesn't have, or is there another reason it was replaced?

[poloxskier]

:---: They changed it yet again. It was originaly a bar like the older riblets and I asume most older chairs. When they found out that it wasnt working very well they changed it to an electronic eye. I'm kind of suprised that they changed it again.

[highspeedquad]

I think I do remember that it once had a bar. It was a while ago, but I do remember it.

[poloxskier]

Well even the electronic eye looked like a push bar because they bent a bar to mount the eye and the reciever to.

[liftmech]

The string is prbably attached to a 'proxy switch', which is a magnetic switched used quite commonly on lifts. The end of the string is probably tied to a steel plate which is stuck on the sensing face of the proxy. If the string, and consequently the plate, is pulled off the proxy, it trips the internal switch. Am I correct on this, since I haven't seen it yet?

[puk]

The string stop gate may be a fix to a common problem inherent in photo sensors. Frost and snow can hamper the sensors from working properly in adverse conditions. Also, depending on where the power supply is located, voltage drop can effect the reliability of these types of sensors. String and or wand type stop gates are quite reliable although the wand types are more prone to wind trips. One other note is that some lifts use a photo sensor to detect a restraint bar in the down position but is typically done with a piece of reflective tape attached to some portion of the restraining bar.

[highspeedquad]

I do believe that you are right, Liftmech, as I would have guessed, that the string is attached to magnet.

So if enough snow gets in one of the eyes then the switch could trip unnecessarily?

[Mike]

poloxskier, on Feb 24 2005, 07:33 PM, said:

Well even the electronic eye looked like a push bar because they bent a bar to mount the eye and the reciever to.
<{POST_SNAPBACK}>

???


anyways, from what I've seen on the safety gate at snowflake is that there is a wire...not a string...with a plug at either end. The wire just completes a circuit. Since the safety gate is at the return end of the lift (bottom drive lift), there would be a voltage drop on the comm line. The reciever also was "blinded" by the sun.
One other concern is someone riding the bullwheel and tripping the photo sensor and the stoned operator not realizing that the safety gate tripped and restarting the lift sending someone into a maze of bullwheels. The "rope" type safety gate requires the operator to plug the safety gate back in and hopefully see why it tripped.
The operations of the lift require the operators for all stations to drive to the bottom (drive end) and ride the lift to their scheduled position. This can be a PITA on a snow day with snow falling off chairs onto the photo cell.

[poloxskier]

highspeedquad, on Feb 25 2005, 03:56 PM, said:

I do believe that you are right, Liftmech, as I would have guessed, that the string is attached to magnet.

So if enough snow gets in one of the eyes then the switch could trip unnecessarily?
<{POST_SNAPBACK}>

The same thing is true of the photo eyes used for racing. I have been to many races, most frequently at Vail, where the snowflakes were too big and would set off the eye at the bottom of the course.

[highspeedquad]

Come to think of it, the string might have been plugged in, but it was sagging, like a string would if it was loose, so I don't think it was a wire.

[Mike]

highspeedquad, on Feb 25 2005, 05:10 PM, said:

Come to think of it, the string might have been plugged in, but it was sagging, like a string would if it was loose, so I don't think it was a wire.
<{POST_SNAPBACK}>

Lets just say I know the installer very well!

[highspeedquad]

So you are dead positive that the string, wire, or whatever it may be is a wire?

[Mike]

Since I installed it, yes, I'm positive!

[highspeedquad]

Is it just coated with the typical white protective cover?

[liftmech]

Mike- did you make up a length of SO cord with a standard plug at the end, or is this a special Poma product? Just curious. I guessed it was a proxy setup because the cord was described as a string. That system also requires the operator to go out and place the plate back on the proxy.

[Allan]

Mike, on Feb 25 2005, 04:23 PM, said:

Since I installed it, yes, I'm positive!
<{POST_SNAPBACK}>

heh :) I didn't think it was piece of string when I read it - we use a plug system on our t-bar too.

[Mike]

It is a very simple system... The wire has two male plugs on either end that plug into standard electricial type outlets (picture a short extension cord with two male plugs). The wire and plugs are wired one for one and one the outlet just has a jumper connecting the two pins together. The other outlet has VDC connected on one pin and the safetygate signal connected to the other pin. When the wire is pluged into both outlets, it makes the circuit. It is a very cheap setup that took care of a few problems we were having with the photo eye system (which we use on all other pomas).

[highspeedquad]

I did think that the "plates" at the end of the string looked like plugs. Don't ask me why.

So when did Breck upgrade all of their high speed lifts to the photoeye gate. I seem to remember one of the high speed quads having one of the metal bars at one point. It might have been the Colorado.

[Mike]

we've had the photoeyes for years...All the new pomas we get use them. Colorado, being one of the older lifts may have had a bar but that was before me. One good thing about photo eyes is that skiiers don't lift their legs over the stop gate (like some do with bar or rope style). You also don't have to deal with bent wands from people getting tangled up or corrosion with plug style stop gates.

[highspeedquad]

Mike, on Feb 26 2005, 09:47 AM, said:

we've had the photoeyes for years...All the new pomas we get use them.  Colorado, being one of the older lifts may have had a bar but that was before me.  One good thing about photo eyes is that skiiers don't lift their legs over the stop gate (like some do with bar or rope style).  You also don't have to deal with bent wands from people getting tangled up or corrosion with plug style stop gates.
<{POST_SNAPBACK}>

That's what I seemed to think, because on the glossary under the safety gate it said that if you ride around, don't try and avoid the gate, and I doubt that people would have problems with the laser because they don't know that it's there or they don't have to worry about hitting it.