4 Post Lift Help! Thank you

[GreatWhiteNorth99]

Good morning All,

First of all, thank you for letting me join this forum, and I look forward to participating and providing some general help.

I bought a well-maintained and used 4-post lift off from a trustworthy source. We tested everything before making any kind of serious decision.

We hauled it back and have it set up at my house. For the transport, we had to disconnect the hydraulic line from the power pump/unit. I was planning on draining the oil and bleeding the system anyway...however, when we had it all connected and refilled the hydraulic oil reservoir and turned it on, the hydraulic cylinder was not moving at all.

The power unit turns on, and I can feel that it is pumping the oil to the line, but the hydraulic cylinder remains fully retracted (please see attached pic for reference). We need to have the cylinder fully extracted to connect the cables. I topped up the oil with new AW32 oil well over the minimum line, but still nothing. It pumps, and when I press the lowering lever, it does relieve the pressure build-up. I had the pump running for about 15 to 20 seconds to see if it would build up enough pressure to move. Nothing.

The hydraulic line is free from kinks and has no obstructions.

Is there some kind of lock on the hydraulic cylinder itself preventing it from freely moving?
Any suggestion is greatly appreciated.

 

[pbon]

I’d google Bendpak or Rotary installation instructions. I recall something about the ram. Maybe it has to be pulled out or bled of air. Can’t recall, unfortunately. Also make sure the hydraulics and/or air to the motor unit and reservoir are plumbed correctly. Reading instructions even if for a different lift might help ensure you did everything right.

 

[GreatWhiteNorth99]

I’d google Bendpak or Rotary installation instructions. I recall something about the ram. Maybe it has to be pulled out or bled of air. Can’t recall, unfortunately. Also make sure the hydraulics and/or air to the motor unit and reservoir are plumbed correctly. Reading instructions even if for a different lift might help ensure you did everything right.

@phon, thank you.
I did read through the installation manual and maintenance manuals but nothing specifically mention this specific issue

 

[jack stand]

I'd chase the fluid to the bottom of the cylinder (take the lines off and pump until you have oil) the first one to get oil out, attach it to the cylinder. Repeat on the other. 15-20 seconds is not a lot of time. Just keep the tank filled throughout the process.

 

[gamescastspencer]

It is a single acting cylinder. Pressure from the pump retracts the cylinder. Weight of the lift pulling on the cables is what extends the cylinder.

Disconnect the hose or hold the release valve and pull the ram to extend it.

 

[GreatWhiteNorth99]

I'd chase the fluid to the bottom of the cylinder (take the lines off and pump until you have oil) the first one to get oil out, attach it to the cylinder. Repeat on the other. 15-20 seconds is not a lot of time. Just keep the tank filled throughout the process.

I will try that! Thank you sir.

 

[GreatWhiteNorth99]

It is a single acting cylinder. Pressure from the pump retracts the cylinder. Weight of the lift pulling on the cables is what extends the cylinder.

Disconnect the hose or hold the release valve and pull the ram to extend it.

Amazing... thank you so much. I thinking it correctly. I will give that a try. Thank you.

 

[gamescastspencer]

Also, if you disconnect the hose, put it in a bucket to avoid a mess, as hydraulic oil will come out as the cylinder is extended.

 

[GreatWhiteNorth99]

Rogers that. Maybe this explain why the cylinder was "locking up" when I had it pumped. I thought that there was some kind of rotational lock on the rod to cylinder, so tried to rotate the rod while some pressure on the cylinder and felt it very stiff and I wasn't able to rotate it.

 

[N_Jay]

Does that cylinder extend or retract under pressure?

 

[c39er]

You might use a come-along to pull the ram out.
That's how I've had to do my new Rotary and BP lifts.

 

[22-W]

Pretty sure you will have to do like others said. Put valve in down position and pull piston out. Mine comes right out by hand.

 

[pbon]

I recall having to pull the rod out of the ram and it being difficult. But this was 8 years ago and on a Bendpak HD9. This makes sense if what is written in a post above is correct that pressure retracts and the weight of the lift coming down extends the ram. I am sure I have looked but obviously have not paid close enough attention.

 

[GreatWhiteNorth99]

Does that cylinder extend or retract under pressure?

I originally thought it extends under pressure but I was completely wrong

 

[GreatWhiteNorth99]

I recall having to pull the rod out of the ram and it being difficult. But this was 8 years ago and on a Bendpak HD9. This makes sense if what is written in a post above is correct that pressure retracts and the weight of the lift coming down extends the ram. I am sure I have looked but obviously have not paid close enough attention.

It was not easy but I used some ratchet straps to "break" the rod loose, then use lower body power to pull the rods out. It took me a good 45 min to an hour but worked! Slept like a baby.

 

[GreatWhiteNorth99]

*A quick update with some pics*

Got it all pulled out. Thanks to all of you and a special thanks to @gamesstopspencer.

I decided not to undo the hydraulic cable, because I didn't want to introduce any air into the system but it was quite stiff and hard to pull it out.

It might have been easier to pull out the rod if I had the line connection at the hydraulic cylinder disconnected, so that the thick oil doesn't have to travel all way to the reservoir, but did the brute force method. Just remember to undo the cap at the reservoir and put oil bucket at the reservoir area because it will leak out. I had about 4 to 5 litres coming out of it at the end. Mind you, had the reservoir pretty close to full.

After pulling out the rod, I attached the cables, except the last one, to the end of the rod. I disconnected the cable end from the post so that I can connect the cable to the rod. I am in my 30s and settled in so more formally building out our garage, so looking to connect with yall on some 4 post lift stuff and general garage discussion. Thank you again!

 

[N_Jay]

The hydraulic system (either in the cylinder or elsewhere has a restrictor to prevent fast movement should pressure be lost.

Its a safety device.

 

[GreatWhiteNorth99]

Also, I forgot to mention that due to my occupational background I tried using premium ChatGPT and Copilot (both artificial intelligence tools) to figure this problem out. I was detailed with my problem but both, despite my stupidity around hydraulics, failed to properly assess and solve the problem.

This further suggests that people's experiences and interactions are more effective than AI.

 

[GreatWhiteNorth99]

The hydraulic system (either in the cylinder or elsewhere has a restrictor to prevent fast movement should pressure be lost.

Its a safety device.

Good to know. Thank you.

 

[N_Jay]

Off Topic, but I find public AI to be terrible with all technology outside of coding.