Frog Hydraulic Lift Issue: Descends Instead of Lifting - Replaced O-rings, Assembly & Oil Check

Question

Hello, colleagues, I have a hydraulic lift as in the photos. I took it apart, replaced the o-rings with new ones and the effect was the same. Those, the lift empty when raised to the very top, begins to descend despite the fact that it should not. The oil is max. There is air in it. What could...

Anonymous · Answer

And whether there should be a spring between (3) and the screw

ziooober88 · Answer

I do not know. I got it for repair, but if anyone lost something, I have no idea. That is why I try to understand the subject of how it should look like. The central pin of position 3 has such a recess on both sides for the shot. But there is only one shot. Maybe there should be two sharps there?

zyga c · Answer

The ball should be right behind the screw. There is a small dimple where the ball sits centrally. Check the ball for squashing or replace it with a similar one for a bearing.

Anonymous · Answer

Look carefully at the balls and ball nests, especially item 1.
Position 3 is tightened and should hold. Put the ball (item 1) into the socket, press it with a non-hardened steel rod and tap it lightly with a hammer. This is how I repaired the 10t lift. In my case, the extreme protection was the extension in the cylinder. In this frog, the protection is probably in pos. 2, tapping the ball will not hurt.

Added after 3 [minutes]:

Look carefully at the balls and ball nests, especially item 1.
Position 3 is tightened and should hold. Put the ball (item 1) into the socket, press it with a non-hardened steel rod and tap it lightly with a hammer. This is how I repaired the 10t lift. In my case, the extreme protection was the extension in the cylinder. In this frog, the protection is probably in pos. 2, tapping the ball will not hurt.

ziooober88 · Answer

Buddy, what are you talking about? Buddy, should I hit this ball from position 2 from the pump? She's stiff with this plunger. And let someone explain to me what item 1 is responsible for? What is she doing and what is this ball spring for?

saskia · Answer

Maybe in the link you will find some information about the diagrams of different jacks.

Anonymous · Answer

The author writes: Buddy, should I hit this ball from position 2 from the pump? She is stiff with this plunger. So this ball is in the end valve opening system and there may be a leak on the tm valve. Item 1 is the pump check valve pos. 2. Added after 14 [minutes]: There is something in the hole of position 2. Is it not a pin for the bush pos.3

ziooober88 · Answer

Thanks colleagues for the suggestions. But I also did such an experiment. I wrung out everything that was in position 1 and position 2. I poured oil into position 1 by lifting the piston up to suck oil. Position no. 3 was closed as it was during work. And the effect was that when I lifted the piston up and poured the oil, the effect was the same as always. That is, the piston popped up and held it gently falling. Does this tell you something?

saskia · Answer

inside there is a piston check valve (a ball with a special rubber) which is also a pump check valve.
It is most likely accessed from the inside of the actuator piston.
There may also be a leak between the piston and the oil reservoir.

ziooober88 · Answer

The lift could not be repaired. I mentioned a few things in it but unfortunately it did not bring any improvement. That's why I bought a new working one.

Frog Hydraulic Lift Issue: Descends Instead of Lifting - Replaced O-rings, Assembly & Oil Check

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