Elevator question - floor return.

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electrofelon

electrofelon

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Cherry Valley NY, Seattle, WA
I didn't get scolded too bad for my gas questions, let's try this: 😂. Working in this 3 story plus parking garage building, and probably will be working there for years. Elevator has this super annoying "floor return" function where it always returns immediately to the 1st floor. I want to disable it. Anyone know how or have an elevator guy you could ask? I looked at the control cabinet and the prints but didn't see anything that jumped out. It must be a setting that can be adjusted/deactivated......might just be a matter of knowing the correct term or jargon.
 
Don't even think of messing with an elevator. If you do you probably will not have to worry about your gas question since you will be spending the rest of your life in courts defending your self for tampering with an elevator. If the building owner has questions or issues with the elevator tell them to contact a licensed elevator contractor.
 
curt swartz said:
Don't even think of messing with an elevator. If you do you probably will not have to worry about your gas question since you will be spending the rest of your life in courts defending your self for tampering with an elevator. If the building owner has questions or issues with the elevator tell them to contact a licensed elevator contractor.
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Obviously I'm not going to mess with an elevator, I'm just going to disable the floor return function if possible.

Looks like the correct term is "home landing" or "parking".

This elevator is maybe old enough that it might just be a jumper and not a programming issue.
 
There is likely a good reason for first floor return. Since this is a hydraulic unit and I will assume exposed to freezing temps, they intend to keep as much oil from getting cold which can affect valve operation.
 
dpeter said:
There is likely a good reason for first floor return. Since this is a hydraulic unit and I will assume exposed to freezing temps, they intend to keep as much oil from getting cold which can affect valve operation.
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Sounds like a good working hypothesis.
 
dpeter said:
There is likely a good reason for first floor return. Since this is a hydraulic unit and I will assume exposed to freezing temps, they intend to keep as much oil from getting cold which can affect valve operation.
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Winner winner chicken dinner! Also, since it is hydraulic, don't want to park it on an upper floor with the shaft extended, puts wear on the shaft seals, plus the shaft can corrode. Have a lot of experience working with elevators and finicky elevator contractors.
 
gadfly56 said:
Sounds like a good working hypothesis.
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dpeter said:
There is likely a good reason for first floor return. Since this is a hydraulic unit and I will assume exposed to freezing temps, they intend to keep as much oil from getting cold which can affect valve operation.
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The Hydraulic piston usually located in the base of the unit? At the first floor, wouldn't that leave most hydraulic fluid in the tank and not the piston? Tank indoor or outdoor?
 
Usually, the tank & pumps ("the machine") is in a freeze-protected room and may even be an oil heater to keep it flowing. Yes, the piston/ram is under the car and rests mostly in the cylinder where it's protected, which does push most of the fluid back into the tank. Since in most cases, the cylinder is in earth, it's also freeze-protected.

There are some combined hydro/cable elevators that use a set of pulleys over a cylinder as a distance multiplier, but I've never seen one in a commercial building.

electrofelon said:
The thing is quite low on oil so probably due for a service.
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If it's quite low, it's way past due for service.... sounds like there isn't a maintenance contract on it. License is probably expired then, too.
 
dpeter said:
There is likely a good reason for first floor return. Since this is a hydraulic unit and I will assume exposed to freezing temps, they intend to keep as much oil from getting cold which can affect valve operation.
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It also occurs to me that when the piston is extended the column of oil is exerting more pressure on all the seals in the system than it does when the elevator is all the way down.
 
ggunn said:
It also occurs to me that when the piston is extended the column of oil is exerting more pressure on all the seals in the system than it does when the elevator is all the way down.
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I don't believe that to be correct. The weight and pressure shouldn't change with car height. Whether the piston is mostly in or out of the cylinder, the total weight doesn't change. The most wear happens during travel.

Adding or removing load weight most likely does alter static pressure, and I imagine the pressure rises slightly when ascending, and drops slightly while descending, but the elevator position is about displacement, not pressure.
 
ggunn said:
It also occurs to me that when the piston is extended the column of oil is exerting more pressure on all the seals in the system than it does when the elevator is all the way down.
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There are INDUSTRIAL elevator applications where the "car" or platform sits on rigid supports at the bottom relieving "all" load induced pressure.

Again, I don't know about personnel elevators, but telescopic cylinders are used. The pressure to extend on smaller sections is higher for the same load vs. larger sections. This is common on dump devices where the cos(theta) explains lower forces required at greater dump angles.
 
LarryFine said:
I don't believe that to be correct. The weight and pressure shouldn't change with car height. Whether the piston is mostly in or out of the cylinder, the total weight doesn't change. The most wear happens during travel.
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Wouldn't the pressure at the bottom of a tall column of oil be more than that of a short one? With water it's 1ATM for every 33 feet or so.
 
It would be, but when the operating pressure is probably in the 2000+ PSI range, an extra 2 PSI per foot (give or take) isn't going to make much difference- for a 10 floor building, which is tall for hydro elevators, that's only an extra 200-250 PSI
 
LarryFine said:
The column height isn't changing. The piston is being displaced.
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I do not see how the piston is being displaced without the height of the column (below the piston) changing.
Are you saying that instead of being cycled between the column and a holding tank, the oil is being pumped between the volume above the bottom of the piston and the volume above the piston, inside a hollow shaft that supports the elevator?
 
No, it's a typical piston in a cylinder, and the oil is pumped in and (usually) gravity returned, just as you suspect, but here is no seal at the bottom of the piston.

The oil inlet fitting is near the top of the cylinder, and the piston is always surrounded by hydraulic oil. Thus, the oil height is always that of the cylinder.
 
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