Motorcycle lift manual to air operated

[rdjnny]

I just replaced my hydraulic operated lift with a 10 ton air operated bottle style jack, it required some modifications.
It works great, my question is bringing the lift down without using the bleed off valve, right now it goes up with air pressure but it wont come down
without turning the bleed off manually, is there a way to release the pressure another way at the air supply to lower the unit?

Thanks Rick

[Rick]

The ones I have seen/used the air just takes the place of the hand pump, you still have to use the bleed valve to lower the jack. There is a check valve between the pump and the cylinder, this check valve is bypassed by the bleeder valve to let the cylinder retract.

[BadDog]

I've been pondering the same problem. I bought an Enerpac style air-over portable power source. Like a shoe box with a rocker lever on top. And I have a casual desire to convert my 50T press, a Blackhawk 10T Porto-Power, my engine lift, and big tubing bender over to use that. Only the Porto-Power and tube bender is straightforward due to the same problem. I think I (and you) could just remove the check valve, and let the air-over box handle it all. But I also want to keep the manual feature of the press for "feel" jobs, and also haven't done the math to be sure it will still produce the theoretical 50T limit either.

[rdjnny]

That sounds like a plan, let me know if you decide to do it and the results
right now I'm just using the bleed valve, I haven't had time as of yet to try to resolve the issue.

[whateg0]

The portapower style cylinder and the engine hoist air/hydraulic rams are not the same thing. I suspect the jack you are using is similar to the engine hoist ram, or a tall floor jack? As Rick said, the engine hoists just replace the pump assembly with the air driven one. The rest of the circuit remains the same. A portapower uses a "normal" cylinder, either simple single acting, or single acting with a return spring in they cylinder and all of the gating, overload, etc. are built into the pump, whether it's a hand pump, air/hydraulic, or electric. The math says that my 8T engine hoist ram develops about 11.5 kpsi to get to 8T, so the internals should handle the 10k portapower pumps just fine. So, in theory, you could remove all of the engine hoist ram gating except the check ball that isolates the tank and sub the portapower hose for the existing pump assembly and everything would then be controlled by the remote pump unit. A pic of the cylinder you are using would be helpful.

Dave

[BadDog]

Exactly what I was thinking. Porto-Power and home made simple ram setups (like common for tubing benders, often using cheap surplus cylinders) are simple, just adapt power source and go. Adapting a hand pump like engine lift or press to work with the air/over power supply should also be simple enough, if you basically convert it to a simple ram by modifying the pump/old/release mechanism so it is controlled completely by the remote power supply.

Another option is using the hand-pump + air/over units available from suppliers like HF. I did that on my old "20T" HF press. And they make them for the typical "2T" engine lifts. Just bolt on and go.

But keeping an existing hand pump ram with functional with both the hand pump and remote air/over operation requires some more thought, and perhaps tradeoffs. I suppose it could be as simple as adding a new tap for the remote. Then it acts like a simple ram with the remote. Just let it retract with the no longer desired power source, and start operation with the desired power source. Assuming internally limited from over extension, it should be good. And safety bypass still remains functional. I can imagine other options as well.

Lots of casual pondering so far, but no concrete plans or action...

[warmstrong1955]

Just watch the pressure. Most port-a-power pumps, and cylinders, are 10,000 PSI max.
Most regular hydraulic cylinders, are not.

[BadDog]

Yeah, definitely some focused thoughtful consideration before starting. That's why I was thinking it might be good to keep the safety bypass. If you exceed limits, like hitting the internal range limit, it just bypasses (as long as you don't over-run it). With the possible exception of the big press, and maybe the PP depending on application, the cylinder limits aren't going to be the limiting factor anyway. I think it's hitting that range limit that will be the most likely issue for over pressure when using a remote power unit. There, the bypass in the power unit may not be remotely low enough to stop catastrophic damage, and simple cylinders don't have internal safety bypasses.

[warmstrong1955]

It would be easy enough to add a safety relief valve. As long as the pressure is high enough above where you need to be to lift, with the right valve, internal leakage should be minimal.

[whateg0]

One issue to consider if adding a remote pump capability to use with the existing hand pump is fluid return. If a normal jack is used, the return goes back to the tank around there cylinder. A remote unit usually has the tank built in to it.