Hydraulic lifts can operate by direct or differential drive (traction). Depending on the characteristics of each installation, it is preferable to install one or the other.
Direct drive (or 1:1 direct pull)
This means that for every 1cm of piston travel, the cabin will also move 1cm. In this type of installation, it is necessary to have a deep pit or hole where the piston can be placed.
Differential drive (or indirect traction 2:1)
This means that for every 1cm of piston travel, the cabin will move 2cm. This is possible by means of a pulley and a cable system that doubles the cabin travel. In this case, the installation does not need a deep pit, since the piston is installed on the side of the hole. It is ideal for long travels.
41 comments
Hello good evening, my question is why the inlet of the bucket that joins the oil installation with the valve is broken, this is the second time that I have had this problem, it is a GMV equipment provided at the time by Soimet industries of Argentina, this is installed in the Boca Jrs. Club and is used for journalism and executives, it has an approximate extension of 20 meters, 2 in 1 traction, it has only one door and all the stops (four) are all on the same side, this valve is the one that has the oil drain that the piston releases, the engine room is on the 3rd floor and from the central to the piston it is connected by a 2-inch galvanized pipe. I thank you in advance for your valuable information. Oscar Carmona
Thank you for your comment, Oscar. From your observations, we understand that the leak is occurring due to the piston seal, which we call the TSE seal. If the piston is installed in a high-traffic elevator (as is your case) and has been in operation for a few years, it is possible that this seal has worn out and needs to be replaced. We hope that the answer has been helpful.
Hello, good evening. I have an elevator that does not go down because the parachute valve is being released. How can I lower it so that all the oil comes out of the piston so I can check the parachute valve? Or why might the valve be being released?
Hello Jorge!
In order to give you a more precise answer to your question, we would need you to specify how many stops the elevator makes before the parachute valve is triggered. To go down and remove the oil from the piston, you must press the red emergency button. In any case, remember that the adjustment of the parachute valve must be carried out by a professional in the sector, and under no circumstances should it be done by a user. If you prefer, you can call us at 902 34 52 34 or leave us your answer here so that we can resolve your query. Best regards.
Good morning, It hardly goes down at all, you push it up a little and then when you go to make it go down either with the down valve, or with the contactors or with the emergency valve, the parachute valve is immediately released. My question is, could the parachute valve have become stuck? And if not, what could be done to remove the oil from the piston to see what is happening to the valve?
Good morning Jorge,
This is probably because the parachute valve core has come loose. The only solution is to loosen the bleed screw (located on the top of the cylinder) without removing it, and let the oil drain into the pit. We hope you can fix it! Regards.
Hello, the question I wanted to ask was that I have a 7-stop elevator and it is a GMV hydraulic elevator. What happens is that when this equipment goes down it feels like a shock that seems to me to be the parachute valve that is activated; and immediately when I do it, it goes uphill and it goes up very slowly, and this happens to me all the time as if due to this shock of activation of the parachute valve it loses pressure and does not want to go up normally but very slowly.
To remedy this I do the maximum pressure regulation that the GMV manual tells me and it begins to function normally until the knock appears again and returns to the previously mentioned condition, what I would like to know is if there is any way to discard this valve since in my opinion it is damaged. I have already reduced the descent speed and opened the parachute valve more and this valve continues to activate, my doubt also comes because when I press the manual emergency descent button this valve does not activate, it is a bit strange.
Well, I hope you can help me with this problem. Thanks.
Hello Julio,
As the problem is presented, what is most likely happening is that there is a foreign body inside the circuit, and this causes the parachute valve to be triggered. When the parachute valve is activated, the speed of descent decreases, also causing that in order to go back up the pressure must be increased and the object that has been left in the parachute valve must be unblocked.
If the elevator is new, this body may be a plug from the pipes that was left inside during assembly. If the elevator is old, the ring at the bottom of the stem may have come loose. In any case, it must be removed from the circuit, and to do so, follow these steps:
– fully open the parachute valve adjustment screw (until it stops)
– take several trips in the elevator (the last one to the lowest floor)
– close the stopcock and release the pressure
– remove the filter inside the stopcock and remove the foreign body from the side opposite the pipe connection
We hope you can resolve this issue. If not, please do not hesitate to contact us again.
Greetings!
Hello, I would like to know how deep the pit is for the side piston elevator specifically, hoping for a prompt response. Best regards.
Hello Rocio,
If we are referring to a lateral direct pull piston, it will depend on the route that the elevator has to travel, although normally the pits are around 1.2 m.
We hope this answer helps you. Best regards!
I have a problem, the elevator goes up but when it reaches the second level it stops because of the limit switches. The question is, once it reaches the indicated stop it starts to slowly descend. What could be happening?
Good morning Gerardo,
The fact that the elevator starts to descend slowly when it reaches the floor level may be due to several circumstances that should be checked. If it is an electric elevator, it should be checked that the brake closes the traction pulley correctly and does not cause the pulley to turn. Likewise, it should also be checked that the cables do not slip.
On the other hand, if it is a hydraulic lift, it must be checked that there is no internal or external leak in the valve group, or any associated component (hand pump, emergency button, etc.), or the solenoid valves that control the descent of the cabin (dirty filters or a seal in poor condition). Finally, it must be verified that the closure of the non-return valve of the valve group, which keeps the cabin on the floor, is in good condition (check for worn seal, worn material or dirty filters).
In the event of an oil leak, at the two points I have detailed, this will cause the elevator to slowly descend when it reaches the floor. If these points are not repaired, this descent will progressively increase over time.
The best thing to do in these situations is to contact the elevator installer or manufacturer so they can inform you of the actions to be taken.
In the case of a hydraulic lift with GMV equipment, you can send us more details about the installation so that we can send you the most appropriate documentation and resolve the problem. If you prefer, you can also contact us at +34 937 745 455 or info@es.gmvgrupo.com .
Greetings!
Hello good evening:
Recently one of the pipes that connects the two parachute valves (there are two cylinders) came loose and all the oil leaked out, causing the elevator to lower itself at a very low speed to the stop:
Is this possible or is there something else? Shouldn't the parachute valves have been activated?
Good morning Jose Luis,
In the event of a break in the pipes of a hydraulic elevator, the cabin would always descend at a higher speed and, as a consequence, the parachute valve would be activated.
From the situation you describe, I understand that the line that came loose is not one of the main lines in the installation but rather a secondary line that is installed between the parachute valves.
Let me explain: in two-piston forklifts, a hose is installed that comes out of each piston and is joined by a central fitting or manifold in order to go to the hydraulic unit. In this situation, a safety valve, called a parachute valve, is installed on each piston, which prevents the uncontrolled descent of the cabin in the event of a break in the pipes. In this type of installation, a small copper pipe is also added that joins the two parachute valves. This last pipe guarantees the synchronization of the action of both valves to stop the cabin in a synchronized manner.
We understand that the cabin descended at a reduced speed, one of the main lines was not completely released, so the cabin did not descend at an excessive speed, which would cause the parachute valve to operate. Instead, it is possible that this secondary synchronization line was released or loosened.
To avoid this situation, it is always advisable to carry out a pressure test of the entire system to verify that there are no small leaks during installation and during inspections, in addition to verifying the correct calibration of the parachute valves.
We hope we have been able to resolve your doubts.
Greetings,
hello,
I would like to ask for your conceptual help to find a solution to a problem I have.
I have two elevators with a GMV valve and a double direct attack piston. What happens to me is that when the elevator is on the ground floor, one of the pistons goes up a little on its own. It could be a matter of pressure difference between the pistons. Then, when starting up, as one piston was already a little out, when starting up, the leveling of the pistons generates a sudden movement in the cabin and a knock is felt.
In some cases, when the piston is purged to remove any oil that may have entered the system, the equipment improves a little and the knock is felt less, but it happens again.
The thing is that I don't have any oil leaks on the pistons at the moment.
The pump outlet is divided in two to reach each piston, but its original route in a metal pipe was not equidistant, that is, the section of pipe to one piston is shorter than the other, but that was the way it was from the beginning and the equipment did not have the problem. Now we changed the pipe on one piece of equipment to a hose and put in the same length and the problem still persists.
any similar fault that you can describe to me or ideas of what I can check to try to fix it?
I look forward to your response and thank you in advance.
Good morning Alejandro,
Although it is difficult to make a diagnosis without knowing more details about the installation and the problem, it is unlikely that it is a pressure difference issue.
If the pistons were telescopic, there could have been a loss of synchronization, giving rise to the imbalance you are describing. If the pistons are telescopic, we recommend that you perform synchronization. Remember that to do this, you need to remove the shock absorbers and fully compress the piston.
If the problem persists, you can contact our SAT (Technical Assistance Service) by calling 902 345 234 or +34 937 745 455 (from outside Spain), where they will advise you and try to solve the problem.
We hope we have been able to help you.
Greetings!
Greetings
In a hydraulic elevator, when the cabin reaches the highest level, how many more cm can the piston extend?
Hello Diomer!
The piston's extra travel will vary depending on the clearance in the elevator shaft. Based on this variable and by calculation, it will be possible to determine how many extra centimeters the piston would need.
All the best!
Hello, I have a GMV 3010 central unit with a 22kw motor. I am just taking over an old installation and I notice too much dirt on the VMD solenoid valve filter, causing it to descend very slowly. Which filters should I check, the motor filter or the shut-off valve filter? Or should I change the oil? To check the motor filter, is there no other option than to send the elevator to the top floor and empty the installation until it is visible?
Atilio
We have a cylinder elevator that without passengers performs all functions normally. And with a load of approximately 100 kg it advances slowly and stops before the 1st level. We checked all the valves and they work normally. We noticed oil on the piston head. Could it just be that small leak?
Good afternoon,
Regarding your query, we have little information to be able to give you a more specific comment. We would need to know which valve group it is. In any case, we are more inclined to believe that it is a valve group regulation issue or a fault in the group, rather than the piston.
If you wish, you can call us at 93 774 57 98 and tell us more about your incident.
All the best.
Hello, I am glad to find this blog, as I am facing an important challenge. Due to a university project, I have been assigned to a project for the installation of a hydraulic elevator for the disabled, maximum 3 floors; which includes the description of an installation plan and the elevator.
The best one is the differential one since it would take up less space.
Therefore, I am turning to you so that you can help me with the above with the information you have.
Greetings.
We are very pleased to be of use to you. In order to provide you with more personalized assistance, we would appreciate it if you could provide us with a contact email where we can send you the information you request.
In the meantime, please accept my warmest regards,
Hello,
I have a problem with a three-story elevator in a home.
From the central to the cylinder there is only a 'T' with a pressure gauge, fitting, hose, fitting and elbow. (I have removed the check valve)
In manual operation (without electrical panel) the pump generates 40 bars.
The elevator doesn't go up.
With a tractel I raise it and the stem rises perfectly, (completely straight stem)
Could the pump be failing and still be giving 40 bars?
Greetings
Hello, please help, – I have a 7-stop GMV hydraulic elevator – the infrared door sensor has some cables on the top MODEL Memco Elite Model 618 – my problem was that during an ascent the cable on the right door broke off, I soldered the 4 cables it has inside but it doesn’t work – it detects an object with the usual sound, — but when there is no object the lower LED starts flashing and an intermittent bird-like sound.
According to the manual it seems that the error is “A diode has been timed out”, how do I fix it?
Please I ask for your help earnestly.
Thank you for your attention.
Hello,
Do direct or indirect traction elevators have an overweight, overcapacity or other sensor that prevents them from starting when the nominal capacity is exceeded?
Greetings
How much can a cylinder cost for a hydraulic lift with a cabin travel of 13m and a maximum load of 300kg?
Good afternoon Jose Luis, thank you for your query, our sales department will contact you shortly to give you an answer,
Good afternoon
We have a private hydraulic lift with two stops and we have a maintenance contract with the company that installed it for us. The fact is that they tell me that the piston seal needs to be changed to prevent oil loss and that the cost is around 1200 plus VAT. This seems excessive to me and since I don't understand this subject, could you help me and advise me on what we need to do and if that is the usual cost?
Thank you so much
I have a DHM-400 elevator. Currently it goes up to a height of 3.30 meters and now we have modified the floor where it goes up so that it has to go up to 4.60 meters.
I would like to know if with my current height of 1.80, I could grow to that height?
Thank you
Hi, could you explain to me how the 2in1 advance is achieved in hydraulic elevators? Thank you very much in advance.
Hello, the mechanism shown in the figure above that says 1:2, can someone tell me how the cabin doubles the distance traveled by the piston, I don't understand it, I do understand the principle of pulleys, reduction of forces, speeds, etc. (physical and mathematical concepts) but specifically this system I don't understand how it doubles the displacement, according to what I can analyze it seems to me that it is still 1:1, I would appreciate the help, Thank you and greetings!
Hello, I hope you can help me. Due to an oil leak, we have proceeded to change the piston seal of the hydraulic elevator of the GMV group and the oil leak continues and now even more than before changing it. Can you advise me and tell me why it happens? What must be the problem for this oil leak detected in the piston, oil in the cabin roof and elevator pit to occur? The new seal installed is not from GMV, I inform you, could it be the reason or is there another major problem in the piston head? Thank you for your attention.
Good morning,
I have a dumbwaiter that works with a piston and two pulleys, and it had a travel of 4 floors.
In order to gain space in the room on the top floor, we decided to eliminate that last stop, and our idea was to leave the other 3 in operation.
Now we are faced with the problem that no elevator company or manufacturer gives us a solution (unless it means changing the entire elevator).
But we don't know if it can't be fixed, or if they don't want to do it. I have the feeling that it can be fixed.
I would like to tell you that this dumbwaiter did not previously have a longer route above the 4th floor. I say this because 2 of the companies that have come have told us that the elevator probably had a longer route above the 4th floor, and this is not true. It ends at the ceiling of the 4th floor, and now it ends at the ceiling of the 3rd floor.
Thank you very much in advance.
Good morning, First of all, we would like to thank you for contacting us to resolve your query. With the information we have and without seeing the installation, we cannot give you a solution to your query. Our advice as a manufacturer is that you follow the instructions of your installation or maintenance company, since they know the installation. If your technicians have any questions, they can contact us and we will be happy to help them.