10 replies to this topic

[jkm]

Thank you in advance to taking the time to answer a layman’s question. I’m not in the ski lift industry, but rather a skier who is involved in a bet regarding a technical aspect of detachable chairlifts. My position in this bet is that the grip is the only means by which the chair is held on the haul rope. Once the grip is derailed, the cable is bare when it goes around the drive wheel. The person I’m engaged in this bet with contends that there is “something” attached to the rope in which the grip is synchronized with when it couples with the rope. He claims that the force of springs would never create enough friction between the rope and the grip to prevent the chair from “slipping” on the rope. I, of course, disagree. Having a professional from the ski lift industry answer this question would put the argument to rest.

Thanks so much
Jason

[SkiBachelor]

Well, the grip isn't the only thing that's keeping the carrier to the haul rope. There is also the track rope used on trams and bi-cable gondolas. But the way you worded your question, your right.

[Allan]

You have it right JKM, there is nothing but the gripping force of the springs holding you there. The springs are VERY, VERY strong, and there are at least two (one main, and one backup.)

[liftmech]

You win. Here's proof. See how the grip jaws are clamped onto the rope, with some of the spring washers that provide the force visible on the inside of the grip body.

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[Dr Frankenstein]

I think the DS grips have only one spring.

[floridaskier]

The cable is completely bare as it goes around the bullwheel. You should tell your friend to ask someone about it (after he gives you the money). The grips provide 100% of the force to keep the chair on the line.

[Dr Frankenstein]

There are also some grips that works by gravity. (VR-101, Giovanolla, Yan, etc.)

[Allan]

Dr Frankenstein, on Feb 24 2004, 04:15 PM, said:

I think the DS grips have only one spring.

Look closely, there may be another in the middle of the outside spring. There has to be something in case one of the springs fails.

[liftmech]

The DS grips have 33 Bellville-type washers to provide the primary grip force. If they squish flat, or if enough of them break, there are eight backup coil springs located in the washer housing (which you can't see). The grip force monitor on these grips is a mechanical style; if the secondary springs are providing the force, they push the primary washer housing into a brittle bar in either terminal. Visualise this as the primary washers pushing on one side of the housing, and the secondary springs pushing back. Normally the primary washers are stronger than the secondary springs, but as mentioned earlier, if the primaries lose their pring force the secondaries will overcome that force.

[liftmech]

Dr Frankenstein, on Feb 24 2004, 04:22 PM, said:

There are also some grips that works by gravity. (VR-101, Giovanolla, Yan, etc.)

Yan's grips worked with the assistance of gravity; they still had rubber springs to provide the bulk of the grip force.

[floridaskier]

The gravity-assist aspect was the main reason why it failed