Have had an issue with an MCE x Bucher Hydraulics setup for a couple of years now and its starting to become a much bigger problem now.
The lift is a 3 stage telescopic cylinder acting on a cylindrical glass car that serves 3 floor with about 20m travel. We changed the ram seals 5 years ago and it was running ok until about 2 years ago when it just started relevelling up and down at the top floor. This only happened when people would enter or leave the car and then it would sit there relevelling up and down 10mm above and 10mm below floor level until it received it's homing floor call down to Basement.
I identified a leak in the bucher valve block and rebuilt the down pilot and down spool. It now has no leaks but still has the relevelling issue. There are no leaks in the system now and the lift doesn't sink below floor level over a period of time.
I am wondering if the static pressure is too low (20 bar) or if the MCE LS-QUTE landing system (tape reader) or the HC-CTL board that the tape reader comes back to could be causing the relevelling. Any help would be much appreciated!
See attached photos of power pack and controller setup.
Sounds like it needs bled. It's a PITA but it has to be bled well to get all the air out of all the stages. Or it will be bouncy.
Also if the internal packing on the piston are wearing out it can cause leveling issues as the moves past the internal packing. Are the stages perfectly in sync and staying that way?
Even a working Bucher valve is junk. It could be over complicated electrical issues (valve control board not working right). Quality valves only have 4 solenoids. Regardless, is the valve adjusted well? One solenoid variable voltage controlled valves are the most finicky valves. Savarias aint worth the 2 cents you'd get for them at the scrap yard.
Have you ruled out other mechanical issues at the top? Stick slip? Tight or sticky rails?
I'd rule out stick slip and other mechanic issues, make sure they are bled well, not a packing issue, rule out the selector if you need to and if all else fails sell the customer a maxton or Blain valve.
We have bled the cylinder but it only fixes the issue for a few hours and then it starts relevelling again. It does it worse on the top floor but when the public start entering the museum and using the lift it will do it on all 3 floors.
The valve is adjusted well and comes into floor ok. It can start relevelling 5 to 10 times when people walk into it from any floor after not being used. It also happens when people leave the car, they step out and the lift pops up 5 to 10mm obviously because the weight has left the car and it starts relevelling.
All stages seem to be in sync as there is no evident jolt as each stage ascends from the other. This valve only has 3 solenoids, DP (low pressure), DZ (overload), Up and Down.
It also has a blain L10 door lock valve.
Yes, we checked the rails and guides weren't binding up at the top but the fact that it can do this on any floor depending on the amount of people that enter the lift is concerning. It's just more prominent on the top floor as it can happen with a loaded or empty car on the top floor, it has to have a load entering or leaving the car for it to happen on the other 2 floors.
I would post a video on here but I don't think I can.
I have uploaded a couple of photos of the cylinder.
- fold down the selector board and look at the magnetic sensors. specifically the level up / level down ( i think they call them stu / std ). if they are loose, your leveling zone may be too tight and will have a hard time leveling into the floor
- if the top floor is more of an issue than the others, you may need to look at the magnets on the tape, make sure they are glued / placed correctly. typically a paper or plastic jig is left on the cartop or machine room after install to help you determine spacing. also i believe the back page or two of the prints should show proper selector installation.
are all of the floors roughly the same travel or is the top floor a short floor? leveling speed is somewhere in the 4-8 fpm range?
Level up and level down are SLU and SLD but they are not used on this board so level up and level down must be used by STU and STD (step up and step down) maybe. The strange thing I found is we have 3 of the same elevator setup at this museum, all using MCE x Bucher. On the lift we are having issues with, STU and STD are both active when the lift is at top floor, the other lifts only have STD active when at the top floor so I'm not if I'm onto something there.
We have used the jig to check the distance apart for the magnets and also checked the length of each magnet and their height from one another.
Yes, all floors are roughly the same travel between each other. Not sure what the levelling speed is as it only lets you choose Relevelling, Deceleration, Slow speed and Soft Stop in V or V/S on the Bucher Delcon control.
I would guess your other cars are a different number of stops so the top floor is a different floor than this car. STU and STD are used to signal step up or step down when the car is running but when at the floor they’re used for binary position. I’ve seen this at one floor from a broken magnet that’s halves have spread apart but not your problem if it happens at other floors. It does sound like your dead zone might just be set too tight but if level up and level down aren’t used what’s actually triggering the relevel? I’ve never worked on one of these valves before. Does it store a floor table and trigger its own relevel?
Yeah that makes sense, so they're either on or off depending on the floor.
Level up and level down are used because on the MCE controller when this is happening it constantly says level up then level down in the monitoring screen. It just isn't using the inputs that the book mentions (SLU and SLD).
While the lift is relevelling, STU and STU stay on but it switches continuously between ULM and DLM (up levelling marker and down levelling marker) which makes me think it's got something to do with the magnets or switches but the magnets are glued and not noticeably damaged. I don't think it's the cylinder as when a load of people get in the car it maybe moves 10mm max. Otherwise the system is holding pressure. With the ball valve closed it holds 20 bar and drops 5 bar over 10 to 15 mins which is ok. With it open, no drop at all. The car doesn't sink with the power off and ball valve closed either.
When this event occurs is mostly when people walk into it from a floor or leave the car and then it starts but only about 2 times on the 2 lower floors, when this happens on the top floor it can sit there relevelling about 10 times before it will actually leave regardless if it has call on for another floor. The only floor it does it with an empty car is on the top floor but not every single time.
The only thing we haven't dug deep into yet is the tape reader switches. The magnets especially on the top floor are in the correct position glued so we can't adjust them anyway.
This has to be your level up level down sensors. They’re adjustable up and down to set the deadzone. Move them out an 1/8” or so then soften up the stops a bit to hit the floors again.
So after going back I adjusted the level up and level down sensors and also adjusted the delcon parameters (decel, slow speed and soft stop) and it worked! But only with an empty car.
When I put 5 to 600kg in the (car is rated to 1000kg) it lowers the car on any floor about 15 to 20mm and then will level back up to floor so I've had to move the level up and down sensors out by 10mm each way which seems over the top.
Now I have stopped the relevelling on the up direction but only with half load in the car, who knows what it will do when the car is full. The down direction is different because the levelling sensors are the ones that stop the lift at floor once it hits the second level sensor, it only has to bump up 5mm to relevel back down. Once the load leaves the car on a down direction stop (we used an industrial cleaner and 2 people) the lift car lifts up about 10 to 15mm from the static pressure in the cylinder, hits the magnet and levels back down to floor level. I can't think of anyway to stop this.
To begin with when a load left the car on the down travel when stopped at a floor the STD and STU sensors would leave the stepping magnet so it would relevel so I moved the stepping magnet which sorted that but now its just the levelling sensor which adjusting that won't make any difference as it stops the lift so regardless of where you move the second levelling sensor to the lift will always stop at the end of the magnet.
Maybe the lift sinks too much when people get in and bumps up too high when they leave the car but I'm not sure I can even stop that from happening.
See attached photos of where the levelling sensors have been moved to and the changed top floor magnet position.
I think your system has or is pulling air. Bleed the cylinder (see Y - 1st-3rd stage)? Bleed the hall sensor (see 9)? Do the pistons extend evenly? Is there enough oil in the tank when the pistons are extended? Is the oil temperature in the working range?
Yes, that's the only thing that makes sense but we have bled the air nipples on each stage of the cylinder and there was no evidence of air, just a smooth stream of oil. I feel like there should be a main bleed valve or venting port on the top stage as the 3 "y" air bleeding nipples are only for the seals for each stage.
The pistons all extend ok and are fully synchronised. Temperature is ok always sitting around the 30 degrees celcius range and we have an air cooler installed for when the oil temp passes 38 degrees celcius.
1. bleed L10 Valve (s. l10_gb.pdf doc S.2/2). The control manifold block is higher than the cylinder connection in the pit, because air wants to rise. (sry, I still think of air in the system) 2. Does the hydraulic hose between the cylinder and the control block move or inflate when the pressure changes? The load distribution carrier for the cylinder in the shaft pit is it dimensionally stable or does it bend under load? 3. Check zero point of hall sensor and vent. (s. delcon-300-i-9010270-e-04.pdf & bleed hall sensor.pdf id.9)
I haven't tried bleeding the L10 or the Bucher LVRVF 350, only the cylinder air bleed screws so I'll definitely give that a go.
The hose jolts a bit but doesn't move too much as it's pretty heavy. The carrier in the pit is also stable and not an issue.
The more I think about it if trying another bleed doesn't fix it, it must be the cylinder seals bypassing oil and may be in need of new ones again.
The delcon hall sensor is reading 0.02v so that is ok too.
I have attached a video of what the lift was doing prior to moving the levelling switches out but it sinks down this far when 5 or 6 people get it and then when they get out on a lower floor it lifts up and starts levelling down.
That’s way too much. Has to have air in the line or someone replaced the oil with water. Close the ball valve and load the car. If it still compresses that much there’s air in the line. If not, there’s air in the valve. Have you bled it with the jack’s fully extended? Is the feed line ran overhead? I’ve seen pipe runs that leave a high corner where a bleeder had to be put in the 90. If you bring the dead zone back in to a reasonable distance so the car relevels at less than 1/2”, can it at least just relevel to the floor and stop?
We can't bleed the cylinder's with each stage fully extended as it's impossible to reach. Or do you mean bleed the L10 door lock valve and bucher valve when the cylinders are fully extended?
The feed line leaves the tank, penetrates the glass shaft and heads straight down to the casing in the pit so no overhead run. If I bring the sensors back to relevelling within half an inch the lift just starts relevelling up and down for about 5 to 6 mins straight when people leave the car.
So we sent the lift to the top floor and shut off the ball valve and power overnight with an empty car and it dropped 110mm over approximately 20 hours.
Do you guys think it could be the seals? We did see a very small amount of oil sitting around the seals around the casing of the bottom and 1st stage cylinder casing.
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