Tutorial - synchronization of hydraulic cylinders without regulation and without proportional valve 

Hello. For the applications you mentioned, synchronous cylinders may not be the best option because of the different diameters and forces. I would recommend using a flow divider connected to two equal cylinders. For further questions you could also contact us at www.atphydraulik.ch/en/contact/. Have a good day.

The highest pressure occurs on the rod side of the last cylinder in the line. In a cylinder, the pressure (N/mm 2) is spread across the surface of the piston. On the rod side however, the N is spread across fewer mm 2, which results in higher pressure. This now can be repeated in each cylinder in the line, starting calculation with the resulting pressure of the last cylinder. The Formula for this event is: p1*A2/A1=p2 (Or in general; p1/p2 = A2/A1) For the next cylinder, p2 becomes the new p1. This is repeated for each cylinder in the line.

The second cylinder has a smaller diameter than the first one, so that less oil is needed for the same stroke length. Before adding more oil, you should check all sealings in both cylinders, the fittings and the hoses. For this you have to drain the oil anyway and fill it back up after, but you can make sure that every potential leakage is eliminated. Then, check if there is another mechanical part blocking the movement of the second cylinder. If it still doesn’t work, you should consider bringing your vehicle to a specialist for further inspection

The second cylinder cannot be the same size as the first one for this to function. In the hand drawn schematic you can see, that one part of both cylinders is coloured yellow, as well as the formula AR1 = AP2. This is meant to symbolize the same volume of the two chambers of the different cylinders. To solve your example problem: The easiest way would be to exchange the cylinders 2 & 3 to a size suited for cylinder 1, so a functioning synchronous cylinder system is created. You could also measure the stroke of each cylinder and have them digitally balanced. For a more detailed and specific answer, please contact our sales department sales@atphydraulik.ch and have your problem looked at with schematics and calculations.

That's quite an interesting question. Technically, it most likely would be possible. It will require some engineering work to get to a proper solution. If you are interested in an offer for a system solution or if you would like to purchase such a cylinder, you are welcome to contact our engineers.

Both Cylinders have integrated hydraulic components, which allow the oil to get in the not directly connected section. Kind Regards, Engineering Team of ATP Hydraulik

Mahdi, I'm looking into the same idea with bottle jacks here in the states. I'll be dripping and tapping into the casting. Or possibly using a preexisting port on the hydraulic cylinder.

You are right, the amount of oil sent to the second cylinder is not the same amount as sent to the first cylinder. To achieve synchronization, the second cylinder has to be smaller than the first one. The Piston side volume of the second cylinder should equal the rod side volume of the first cylinder.

The Cylinders are operating at the same speed, but not with the same force. Fluids are almost incompressible which means that for every millimeter cylinder Nr 1 moves, cylinder Nr 2 moves aswell.

he cant help you he is wrong person

At this condition both rod and piston volume should be same otherwise there will be difference in position and speed.

Valves inside the cylinder allow the oil to pass from the piston side to the rod side of the first cylinder. From there, the oil can pass further into the second cylinder, where the same principle is applied. With this technique, all four chambers are being filled up before operating.

The air is bleeded through two separate bleeding screws on each cylinder, preferably directly on the opposite site of the hydraulic connections. Basically, the air collects at the highest point. The cylinder can only be vented if the bleeding screw is also at the highest point. 😉

P1 is different from P2. Important is, that P2 has the same volume as R1, which is P1 minus the volume of the piston rod. There are no rules about the volumes of P1 and P2, except that P2 is smaller than P1. P1 can be 2xP2, but in most cases it varies. I wish you a good day.

Generally hydraulic oils are labeled almost incompressible (0.5% per 100 bar). Although everything is slightly compressible, therefore we use internal valves to provide perfect synchronisation, even with various loads.

Hi Sandra The operating pressure of the second cylinder can vary from almost no pressure (minimal force required to move the piston and the rod) to the maximum pressure provided by the first cylinder, which is then multiplied with the transmission ratio from cylinder 1. This depends on how the weight is distributed. So, if 100% of the weight is located on the second cylinder, the pressure is actually larger than at the first cylinder. I hope my answer was helpful! ATP Hydraulik, Raphael

but how come both volume be equal

@ You've effectively demonstrated an intensifier. But as a synchronized cylinder setup I can't think of too many applications where this can be applied where synchro is necessary as it is tied in series and the bore diameters are different. It's a training video.

@Rajesh 6. The volume is equal because cylinder No. 1 is pushing cylinder No. 2 from its rod side. That means, that you cannot completly fill the cylinder tube on that side, because the piston rod blocks some of the available volume. The difference in diameters between the two cylinders is precicely calculated, so the volumes correspond accordingly. Kind Regards, Raphael

@Kevin H. Actually, there are many possibilities to use synchronous cylinders! But it’s up to the customers specification. Just one example: the smoother you want a double door to open, the closer you can get to the synchronisation by using double synchronous cylinders. Kind Regards, Raphael