9 replies to this topic

[Jordan]

so heres the deal im doing a school project on linear programming and i need so information on lift capacitys and how much horsepower it takes to get a certain amount of people to the top of the lift in a given amount of time and wire tensions that sort of stuff someone PLEASE HELP

[liftmech]

There are huge variables in required horsepower, for starters. Lift vertical, carrier capacity, gearbox ratio, and bullwheel diameter are all part of the equation. There are more but that gives you an idea of the complexity of the math that goes into a lift. My turn for a few questions:
What is linear programming?
What exactly do you want your programme to do?

[Jordan]

its basically graphing with with variables like ie. rpm's x chair length x number of chairs = how many people can be transported to the top in a certain amount of time? i'm looking for the right equation and examples of this kind of thing, after i have that i can factor that in with costs of operation to see what kinds of profit are made

[Emax]

"its basically graphing with with variables like ie. rpm's x chair length x number of chairs = how many people can be transported to the top in a certain amount of time? i'm looking for the right equation and examples of this kind of thing, after i have that i can factor that in with costs of operation to see what kinds of profit are made"

That's going to be some equation! What is your major? I ask that to try and gain some understanding of your starting point - and your goal. On the surface, the design of a lift might seem straightforward - but it is anything but that. Lift capacities are expressed in people/hr - and there are many ways to achieve a given capacity. You need to determine what factor is most important to your model.

[Peter]

The typical capacities are 1200 people per hour for double chairlifts, 1800 for triples, 2400 for quads, and 3600 for sixes, although it can vary a lot with many different factors.

This post has been edited by Skier: 13 December 2005 - 05:36 PM

[Jordan]

ook variables are going to be on a surface lift wire length, number of seats per chair, how many chairs there are, horespower of motor and transmission those are the big factors i need for this to complete my project... belive it or not im just a sophomore in highschool with a C average

[Jordan]

soo i was wondering say you have a 10000(from bottom to top not all the way around) foot regular quad lift on like a 20% grade what are the usual tech specs like engine type, wheel house radius or whatever its called how fast it turns im thinking like a 7.5 radius but what i really need help with is what kind of rope its gonna need how many chairs will fit on it what the engine and transmissions gonna look like power to weight ratios ?

[Kelly]

Well it is complex answer but one time I also was a –C student so I will try to help.
Note: listed variables are somewhat interchangeable in nature. For you junior engineers - this is a simple example lift.

For a smaller double fixed grip lift -
An electric motor runs at 2000 rpm
Electric motor shaft size is 2"
The size in horsepower of the electric motor is dependant on the total rise of the lift
For a double chair 100 hp per 1000' rise is common
That speed is carefully controlled
That speed can be stopped by brakes
That speed is reduced by 100X and the torque is increased by a gearbox (about as large as 4 washing machines)
That reduced speed (20 rpm) is connected to horizontal wheel called a bullwheel. (Note to teacher - this has been cut and pasted). The connecting shaft is 10" in diameter.
The size of the bullwheel is 10' in diameter
The cable (called a haulrope by the industry) lays in a rubber groove in the bullwheel.
The rotational speed of the bullwheel at the groove is 500 feet per minute.
This is the speed of the haulrope.
The haulrope size is partially controlled by the tension applied for traction in the bullwheel groove.
The structure the all of the above is comprised of - is called a drive terminal
Drive terminal strength is dependant on haulrope tension.
The haulrope size is also controlled by the distance between towers
The number of towers can be controlled by terrain and the cost of steel
The sag is between towers is controlled by tension and distance between towers (all credit for explainations should go to skilifts.org a web site about skilifts, maintenance and construction).
The haulrope size is also controlled by the sag, tension, tower distance and rider combinations – look in the nearest backyard for a clothesline for a good example (ask permission first).
The haulrope size is 1" in this example
The haulrope breaking strength is 100,000 lbs
The tension applied to the haul rope is 20,000lbs
The spacing between chairs is 50'
This lift will transport a maximum 1200 people per hour, this is it's uphill capacity.
The capacity of a purchased lift is determined by the marketing department.
The cost of this lift will be $500,000.
The budget for maintaining a quad detachable is 2 times more than a fixed double each year.
The difference between the force applied and the force needed to break is called the Safety factor or Service factor or Factor of Ignorance.
Haul rope safety factors are always above 5 times breaking force
There has been no instance of haulropes breaking under service at ski areas in North America
The people that maintain and service ski lifts are called Lift Mechanics.
The relationship to Lift Mechanics pay and quality and quantity of work can be proportional but often is not.

For size differences in other lifts compared to a double - use the number of additional people in the chairs as the multiplication factor.
All of the above information can be found in our search engine.
I hope this helps – please reply if you have any more questions.

Other links:
http://www.skilifts....?showtopic=3094
http://www.skilifts....?showtopic=2652

Ryan B

[coskibum]

doug at riblet tramways has some good forumulas for capacity and whatnot: http://www.riblet.com/lift.htm

[Jordan]

wow thank all of you... wow