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ryoder

When the machines turn against us

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>My guess is a electrical issue and the motors reversed.

Hard to see how that would happen. With three phase motors that's almost impossible. With single phase motors (almost unheard of at those power levels) you could theoretically get a failed start and at some point the motor could run backwards, but if it did it would run at the same speed it would going forward - and that's going way faster than that.

>Sound likes they're still running inside of the enclosure.

They might be; it might be a transmission rather than a motor failure.

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billvon

>My guess is a electrical issue and the motors reversed.

Hard to see how that would happen. With three phase motors that's almost impossible. With single phase motors (almost unheard of at those power levels) you could theoretically get a failed start and at some point the motor could run backwards, but if it did it would run at the same speed it would going forward - and that's going way faster than that.

>Sound likes they're still running inside of the enclosure.

They might be; it might be a transmission rather than a motor failure.



Yeah, I figured it would be three phase just because of the size of the motor but they would physically have to move two of the phases. Who knows what kind of crazy shit they have going on in that region.
"I encourage all awesome dangerous behavior." - Jeffro Fincher

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billvon


They might be; it might be a transmission rather than a motor failure.



I thought power failure + brake failure, but your explanation is even simpler if the brake is located between motor and transmission.

As mentioned above, there are multiple redundant braking systems. When a Normal Stop is activated from the control panel, the lift will be slowed and stopped using regenerative braking through the electric motor and the service brake located on the highspeed shaft between the gearbox and electric motor. When an Emergency Stop is activated all power is cut to the motor and the emergency brake or bull-wheel brake is activated. In the case of a rollback, some lifts utilize a ratchet like system to prevent the bull-wheel from spinning backwards while newer installations utilize sensors which activate one or more bull-wheel brakes. All braking systems are fail-safe in that a loss of power or hydraulic pressure will activate the brake. Older chairlifts, for example 1960's-era Riblet Tramway Company lifts, have a hydraulic release emergency brake with pressure maintained by a hydraulic solenoid. If the emergency brake/stop button is depressed by any control panel, the lift cannot be restarted until the hydraulic brake is hand-pumped to proper operating pressure.

Source: https://en.wikipedia.org/wiki/Chairlift#Braking
"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

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ryoder

***
They might be; it might be a transmission rather than a motor failure.



I thought power failure + brake failure, but your explanation is even simpler if the brake is located between motor and transmission.

As mentioned above, there are multiple redundant braking systems. When a Normal Stop is activated from the control panel, the lift will be slowed and stopped using regenerative braking through the electric motor and the service brake located on the highspeed shaft between the gearbox and electric motor. When an Emergency Stop is activated all power is cut to the motor and the emergency brake or bull-wheel brake is activated. In the case of a rollback, some lifts utilize a ratchet like system to prevent the bull-wheel from spinning backwards while newer installations utilize sensors which activate one or more bull-wheel brakes. All braking systems are fail-safe in that a loss of power or hydraulic pressure will activate the brake. Older chairlifts, for example 1960's-era Riblet Tramway Company lifts, have a hydraulic release emergency brake with pressure maintained by a hydraulic solenoid. If the emergency brake/stop button is depressed by any control panel, the lift cannot be restarted until the hydraulic brake is hand-pumped to proper operating pressure.

Source: https://en.wikipedia.org/wiki/Chairlift#Braking

Or, one busy day, the brake keeps malfunctioning, locking things up. The owner/maintenance guy jams it open and makes a mental note to fix that as soon as he can get around to it.

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