wonderpony
Well-known member
- Joined
- Jul 24, 2020
Talk to me about the e-brake, please. This actually is helpful. I can't find much on line about how ski lifts work.
Greek Peak Conditions
- Thread starter Campgottagopee
- Start date
Brownski
Well-known member
- Joined
- Jul 19, 2020
The way it was explained to me: The E-brake is basically a heavy spring loaded clamp that is held open by pneumatic pressure. If the operator hits the emergency stop (as opposed to the normal stop button) it releases the pressure and it clamps down hard on the bull wheel, freezing everything in place. The supervisors emphasized that we should NEVER hit it during normal operations because we couldn’t reset it on our own. We had to call a lift mechanic to climb up next to the bull wheel and pump it back open manually. Conversely, if it rolled back, they said to hit it as fast as possible because all the mass of a fully loaded line would be too much for even the E brake if it were rolling backwards uncontrolled. There is a video out there of a catastrophic rollback in Eastern Europe someplace that is absolutely terrifying.
wonderpony
Well-known member
- Joined
- Jul 24, 2020
I have seen that video.
So, there is a normal stop, backed up by an ebrake? And, then maybe that foot or so of sliding backwards on chair 5 should not be as terrifying?
wonderpony
Well-known member
- Joined
- Jul 24, 2020
Thank you. This is huge. Any idea what the make of the chair is?
My Dad worked for Hall decades ago. And we skied together and I asked him a lot of questions about the lifts. So while I am no engineer this is my best layman's explanation for what is going on when a lift bounces.
I believe that all the lifts but Visions are Hall Lift or Hall Lift style counter-balance designs ( not sure about new Lift 3). The weight of the cable, chairs and passengers are all stretched balanced between the two bull wheels at each end with the lift towers carrying the bulk of the weight on the hill. One bull wheel is mounted on a "truck" that rolls on tracks. As the truck rolls back and forth it lifts the floating counter weight (at either the upper or lower ends of the chair). The counter weight is there to keep the cable taught its entire length, but not carry the entire load of the lift. The bounce we all feel is the cable going up and down between the towers as the truck and weights move and as the cables get shorter and longer with temperature. Think of that 3/4 mile long cable as a giant heavy stiff spring or string on a 3/4 mile long base guitar. Its the largest and lowest tuned bass guitar ever made. It vibrates at a very low rate, about once per second, up and down, as the motor starts, pulls and pushes the cable on the bull-wheel. You will go up and down more if you are in the middle of 2 towers that are further apart. Also most chairlifts have a specified range of how much they can back up. Chair 5 feels like its towards the high range, but its also a long lift, which exaggerates the effect. Its unsettling to some.
Believe it or not, this is a very conservative and safe design that goes back to the early days of cable bridge building. They were designed to do exactly what they are doing! The tension and bouncing we feel was actually tuned into the design to relieve stress on the towers and motor. (There is some math involved, of course),
I believe that Visions and the new Chair 3 use some kind of air and hydraulic shock absorbing system instead of the balance weight. But if you look closely you can still see the tracks which allows the cable to stretch and they both have some bounce tool
Anyway, my wife tells me that Bristol did a lift evac today.
You've got it. Different designs use different e-brakes, but the design you mention is the old and safest standard. The chair you refer to had a manually operated friction brake that broke. No backup.
Did anyone else ski today? It got colder as the day went on but the lack of wind and cold temps allowed yesterday's wetish snow to set up a bit. Mars and Arathusia Way were both fairly busy as was Visions, which was stopped at about 9 to do something to the loading carpet. 4 stopped briefly in the morning too. First time this year the place was 100 % open, although a couple of the non snowmaking areas were thin. The crowd seemed lighter to me than yesterday. All in all an A- skiing day.. Not perfect. Real close tho. Lots of out of towners were here for the 3 day weekend, but the crowd seemed to spread itself out all pretty well. On the lift I always ask people where they come from and why they ski at Greek. Today I got on several different chairs with people who said they usually go to the Poconos and Catskills. They specifically called out for scorn Hunter, Belle-aye, and Camelback. It seems as if Greek has hit a sweet spot for families who have taken up the sport and want something better.... And.... that something better seems to be our Greek Peak!
5 is a Hall. according to Liftblog.
Bullwheel Failure Injures 15 in Spain
Photo credit: Meteosojuela La Rioja via X The top bullwheel detached from a chairlift in Spain this morning, injuring more than 15 people. The incident happened at Astún, a resort with 15 lifts loc…
liftblog.com
