We have touched on cadencing systems in other topics, so I felt it was time to set aside some space devoted solely to the subject.
Some terms:
-passive cadencing: more commonly known as the chain system, this consists of a chain with a specifically spaced set of teeth on one end of the lift, and a conveyor with teeth on every link on the other end. Both chains run at a constant speed. The cadence chain captures the chair, carries it around the contour, and puts it into the acceleration tyre bank for the trip up (or down) the hill. The conveyor chain does the same, except it does not space the chair. The speed of both chains can be varied to suit several conditions: the conveyor can be sped up or slowed down depending upon temperature, and the cadence can be adjusted for different chair spacing. Both should match as closely as possible, else chair spacing gets out of sync. More on this in a bit.
-active cadencing: the current standard, this is where there are one or two clutches attached to parts of the tyre bank which can very the speed of that set of tyres. The PLC uses the zone switches inside the terminal to turn the clutch(es) on or off depending upon the space of the chair.
Problems with both types:
Chain systems are highly susceptible to temperature. For example, on a very cold day, the haul rope shrinks, bringing the carriage forward. Because of this, the position of the rope in relation to the chain changes (in this case, the rope literally moves further from the chain) causing the chairs to 'come in late'. The opposite occurs on a warm day. The problem can be solved by speeding up or slowing down the conveyor on the opposite end of the lift; if you speed it up you overcome the late issue by placing the chairs 'ahead' on the rope. Of course, when it warms up the chairs then stall out at the end of the tyre bank while waiting for the teeth, so you then have to slow the conveyor chain down.
Active systems eliminate the problems associated with chains, but have a few of their own. In a chain system, if a chair is out of whack it is easy to respace (simply move the chair forward or backward into the teeth). In an active tyre system, it may take several laps to respace as the clutch can only advance or retard a carrier by a few feet at one time. If the clutch goes out (usually an electrical problem) there is no spacing going on at all and it is nearly impossible to fix this.
-Zones and anticollision faults: the lifts PLC monitors the spacing of carriers in the terminals by a system of sensors located at intervals around the rail. Each zone has a time value associated with it; if a carrier is in the zone longer than that value the lift will shut down. This prevents phisical collisions between chairs. If a chair were to stall at the end of the tyre bank, it would cause a zone fault. This is why one needs to monitor where the chairs are arriving in relation to the chain teeth, on that type of system.
I hope this answers some questions. Feel free to post any others you may have.
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Chair Cadencing 101
Started by liftmech, Mar 16 2004 07:28 PM
22 replies to this topic
#2
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Edmontonguy
Posted 16 March 2004 - 07:44 PM
This has always intrigued me. How do they keep spacing on a lift like the banff gondola which has carriers that completely detach and require human power to push around the terminal? I beleive that a timer is used to space the lift as when the cabins are finished loading and placed on the line again in somecases the carrier is held for a few seconds before accelerating to line speed.
#4
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Posted 17 March 2004 - 08:35 AM
The Skyride at the Puyallup Fair (1962 Von Roll) is spaced by a simple visual system: when the departing cabin passes over a certain post in the ground, the release operator pulls a cord and the cabin accelerates down the ramp and on to the haul rope.
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#7
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Posted 17 March 2004 - 12:50 PM
Awesome stuff Liftmech!
When you have a chain drive system do you adjust the speed of the chain relative to the speed of the rope for adjustments? And if so, how do you know you've got it right - is it a simple sit in the return station and watch the carriers arrive and check their position relative to the teeth on the chain?
When you have a chain drive system do you adjust the speed of the chain relative to the speed of the rope for adjustments? And if so, how do you know you've got it right - is it a simple sit in the return station and watch the carriers arrive and check their position relative to the teeth on the chain?
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Posted 17 March 2004 - 06:03 PM
For the human-powered gondolas, like the former 1965 Hall 4pass at PCMR:
I do remember there being something that held the cabin in place for however long was necessary.
What would happen to the lift if the operator for some reason didn't push the cabins through?
I do remember there being something that held the cabin in place for however long was necessary.
What would happen to the lift if the operator for some reason didn't push the cabins through?
- Tyler
West Palm Beach, FL - elev. 9 feet
West Palm Beach, FL - elev. 9 feet
#10
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Edmontonguy
Posted 17 March 2004 - 06:08 PM
I think there is some kind of zone alarm that would be set off if too many cabins are in the unpowered section and the lift would be stopped.
One neat thing about these human power lifts is when a materials car comes into the station it can be removed from the line in just seconds without even having to slow the lift.
One neat thing about these human power lifts is when a materials car comes into the station it can be removed from the line in just seconds without even having to slow the lift.
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Posted 18 March 2004 - 07:32 AM
Older style Gondolas with human conveying systems used steeper sloped deceleration/acceleration tracks (gravity never sleeps) as a design element. The sloped tracks were set to work best in the upper speed ranges. Of course there were a few tiny things the operator had to be aware of.
At slow speeds the carrier never quite made it up the deceleration ramp, this required a push from the operator or the car rolled back to the haulrope detaching area.
At full speed with a full load the car had enough momentum to make the 180 degree turn after detaching, which was ok unless there was a car in the turn.
The anti-collision system was an operator who stood between the cabins and pushed or pulled as necessary, they also doubled as the power for "conveying" the carrier to the launch area.
The spacing system was an operator who adjusted cabins by referencing "match marks" painted on the track for proper distance.
The acceleration area track sloped down to help assist the launching operator push the carrier toward the up-line haul rope. Carrier spacing for attachment was more of an art than science… push sorta hard after the loaded car passes the bent I-beam unless we're on slow speed then wait until it passes the red angle iron.
Needless to say, if grip speed and rope speed often didn’t match this would impart a large jerk to the carrier, which caused grip wear, which helped to employ lift mechanics.
Ryan B
At slow speeds the carrier never quite made it up the deceleration ramp, this required a push from the operator or the car rolled back to the haulrope detaching area.
At full speed with a full load the car had enough momentum to make the 180 degree turn after detaching, which was ok unless there was a car in the turn.
The anti-collision system was an operator who stood between the cabins and pushed or pulled as necessary, they also doubled as the power for "conveying" the carrier to the launch area.
The spacing system was an operator who adjusted cabins by referencing "match marks" painted on the track for proper distance.
The acceleration area track sloped down to help assist the launching operator push the carrier toward the up-line haul rope. Carrier spacing for attachment was more of an art than science… push sorta hard after the loaded car passes the bent I-beam unless we're on slow speed then wait until it passes the red angle iron.
Needless to say, if grip speed and rope speed often didn’t match this would impart a large jerk to the carrier, which caused grip wear, which helped to employ lift mechanics.
Ryan B
www.ropetech.org
#12
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Posted 18 March 2004 - 08:30 AM
Dawson, on Mar 17 2004, 12:50 PM, said:
Awesome stuff Liftmech!
When you have a chain drive system do you adjust the speed of the chain relative to the speed of the rope for adjustments? And if so, how do you know you've got it right - is it a simple sit in the return station and watch the carriers arrive and check their position relative to the teeth on the chain?
When you have a chain drive system do you adjust the speed of the chain relative to the speed of the rope for adjustments? And if so, how do you know you've got it right - is it a simple sit in the return station and watch the carriers arrive and check their position relative to the teeth on the chain?
That's it, at least on the Pomas I work on. It takes half the line to see if you've got it right, since the carriers that are on line already were spaced by the old speed. If this warm weather keeps up I'm going to have to put all this into practise, as the conveyor speed is currently set up for cold weather. The rule of thumb that I've been taugh is the chain should pick up the carrier three to four tyres before the end of the tyre bank (the chain and the bank run side-by-side for about six tyres).
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Posted 20 March 2004 - 07:45 PM
A shot of the cadencing teeth on a Poma Cometition-style lift. Note the second tooth behind the chair, in case it comes in late.
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O_1_cadence.jpg (96.42K)
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#15
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Posted 23 March 2004 - 06:24 PM
That is a retrofit. The Colorado SuperChair, one of the lifts you're referring to, is a twin to the Flyer- installed the same summer and all that. (I think they may be the only vault-drive lifts of that type). So Poma already has experience putting those new turnarounds in- unfortunately I don't think I'm getting one anytime soon. I hear it took them a bit longer to do the Falcon because it is an older design with less room to add things in the contour area. 
but the Falcon, as you may have noticed, has the newer Omega carriers as well- apparently they had enough of repairing the old-style carriers.
but the Falcon, as you may have noticed, has the newer Omega carriers as well- apparently they had enough of repairing the old-style carriers.
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Posted 23 March 2004 - 07:00 PM
I'm going for one min......
When i rode the Falcon back in 96 it felt like the backrest was really loose. And everytime i rode it since no matter what chair i was on it felt loose. is that normal or not? Last time i was on that lift was in 98
for one min......When i rode the Falcon back in 96 it felt like the backrest was really loose. And everytime i rode it since no matter what chair i was on it felt loose. is that normal or not? Last time i was on that lift was in 98
Jeff
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Posted 24 March 2004 - 01:15 PM
I think that's why Breck replaced the old carriers. There were so many different parts, nuts, and bolts, etc, that it was tough to keep it all tight. I don't know when they replaced the carriers, but the Omega-style didn't come out until '97 or '98.
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Posted 25 March 2004 - 04:22 AM
Don't take this as gospel, as it's just my take on the subject, but the first Poma detachable carrier looked similar to the second while having many more parts and such. I'm pretty sure the Falcon had those, while I know that Colorado has the newer style. I don't have a photo of the first carrier style, but if anyone else does, it may help this discussion. I can think of several lifts off the top of my head that have those carriers: Summit and High Lonesome at Winter Park, Piney Triple at Ski Cooper, and A-1, K, and L at Copper. That said, let's move this to another thread so we can get back on topic.
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