6 replies to this topic

[Kicking Horse]

How long does it Take for a Poma Hsq To Come to a stop?

[Kicking Horse]

or any lift to stop

[SkiBachelor]

This question has a lot of answers Jeff. I think you should sum it up a little bit. For example, a full loaded lift is probably going to take longer to stop compared to an empty lift. It can also depend on the lift's drive and maybe if the lift is a top drive or bottom drive chairlift. Oh yea, and don't forget about a lift's length. I just think this question is so complicated that you can't actually have a correct answer and it varies per manufacturer. Maybe there is an average though?

[iceberg210]

Well I would guess that

A rope tow doesn't take a lot to stop because of the mass is so little

However

Physics states that a larger mass takes a larger force to stop

So

The more massive the lift is the longer it will take to stop

[Allan]

A lift must stop within a certain distance, no matter the load or length. Here's a brief table of maximum required stopping distances... (all based on the Z98)

5.5m/s: 33.52 Meters
5.0m/s: 27.78
4.5m/s: 22.5
4.0m/s: 17.78
3.5m/s: 13.61
3.0m/s: 10.0
2.5m/s: 6.94
2.4m/s: 6.4
2.3m/s: 5.88

Here's the formula to arrive at these:
s=stopping distance (Meters)
v=velocity (meters a second)
a=rate of decel (meters a second squared)
Max decel rate is 1.5m/s squared
min. is .45m/s squared.

Equation:
S=V squared/2A

And remember, the mass is being pulled uphill. Take this for example: Red chair before the brakes were repaired a couple years ago took 12 meters to stop empty, and about 6.5 when full.

[liftmech]

The B77 uses a slightly different equation (V squared /8000, where V is the speed or Velocity of the lift) but the results are the same. At 500 FPM, the lift must stop within 31.25 feet. At 1000, it jumps to 125. The Flyer stops in 69 feet (we check it every morning) and the emergency stop takes 88. There is a bit of clarification involved here- the electric motor is used part of the braking force in a normal stop, but an emergency stop cuts all power to the motor so it is no longer part of the brake force.
Stopping distance also takes into account chair swing and line dynamics. If a lift stops smoothly, it can stop faster. If the brakes apply instanly, it will bounce around and possibly injure passengers. Thus we use the maximum stopping distance as a guide rather than a hard-and-fast rule. As you can see above, it takes about half the maximum distance to stop the Flyer, but it is a very smooth stop, so there's no need to lengthen it.
It appears that the Z98 and the B77 don't exactly match; the B77 allows for longer distances based on the formula it uses.

[Allan]

Yeah they changed it a couple years ago, and made the distances shorter. We generally try and make it stop shorter than the max as well. But we don't have 125 feet to work with ;)