In ground car lift oil tank psi?

[harley15a]

Does anyone know what the hydraulic psi is on a vintage in ground car lift oil tank? I am looking to bypass the tank in the ground with a small compressor tank and put it above ground. I know the air psi to work the lift is around 150psi but don't know if the hydraulic side is higher with the Lbs of the car on it.Thanks

[3macboys]

To steal a phrase from a certain author - Unsafe at any pressure - I'd bypass the lift completely and get a new 2 or 4 post hoist that suits your needs.

[Frank DuVal]

Thousands of these are still in service. What is the unsafe part?

[3macboys]

10 hours ago, Frank DuVal said:

Thousands of these are still in service. What is the unsafe part?

There's no safety to them and the older the lines get to them the more likely you are to have a failure - I've got one in my shop which is a 1950's era building.  Even the previous owner, who's father built the building said not to use it.  With nothing on the lift it blew a line leaking out the hydraulic fluid about 2 years after we bought the building.   I don't know how much time you would have to get out from underneath if the lift had a failure but I don't want to find out either.  

[46 woodie]

In the early '70s I stopped off to get gas at a local gas station. I noticed two police cars and a fire department vehicle parked in front of one of the bay's. It turns out that for security measures the owner pulled as many car's as he could fit into the bay, under the lift. Somehow overnight, the lift went down and settled on top of two cars. I never found out what caused the lift to go down and I don't know how old the lift was, but it did a lot of damage to those cars.

[rocketraider]

Don't most of these have a safety lever on the guide ram that's supposed to be set once the main ram is fully extended? 

 

Granted, a two-post is an improvement but a lot of those are hydraulic, and use smaller cylinders than a big in-floor lift. And you still have to engage the safety latches.

 

I'm leery of cable-driven electric lifts. Cables stretch and break.

[F&J]

13 hours ago, Frank DuVal said:

Thousands of these are still in service. What is the unsafe part?

Rocketraider posted the correct safety info  before I could finish adding a pic. 

 

They are totally safe if used properly, and if the safety "lock" is inspected.   They are still being made today, even by the company that first marketed them.  Rotary Lift is that brand name.

 

2 hours ago, 3macboys said:

There's no safety to them

Why say this with zero knowledge on these lifts?  I am adding a pic of one which shows the safety locking pole that has an automatically operated "dog" at the bottom of the safety pole.  In very wet soil, that flip dog pivot pin can get rusty, and then not flip automatically.  If the lift is raised and that dog flips to the lock position as intended, the lift can not drop down.

 

A rusted underground line always starts off as a pinhole leak, and the first warning signs of a long term oil leak will be when the lift handle is pulled to the down position, the lift drops fast for a foot or so (due to resulting air in the main hydraulic piston, just like brakes needing bleeding) 

 

They can't drop to the floor instantly due to a leak because the amount of fluid loss to do that suddenly, simply cannot escape that fast through the small line size of the feed pipe. 

 

 

That safety pole does one other thing and should never be eliminated:  That pole keeps the lift head and main piston from rotating.  If the main piston rotates a certain amount, the piston can then be removed from the in-ground cylinder.  It's designed that way to be able to be removed for service repair.

 

47 minutes ago, 46 woodie said:

Somehow overnight, the lift went down and settled on top of two cars. I never found out what caused the lift to go down

The safety dog was not engaged do to rust, or the lift was not raised to the top to have the dog engage. 

 

 

These lifts are great for anybody who does rot repair to rocker panels, cab mounts, or just wants the car high enough to do body work to the lower sides.  You cannot do that work with a twin side post lift, or a 4 post.

 

 

 

 

[Str8-8-Dave]

Modern electric lifts have a safety support system so if a cable broke or whatever the lift would fall just far enough to engage the first tooth of the lock mechanism of the safety support system.  If I recall correctly some in ground hydraulic hoists have a similar arrangement.  

 

As for the 150 PSI, if that is listed as the maximum air pressure rating that would be with the rated load on the hoist, I.E. the piston diameter of the hydraulic ram is sized so 150 PSI will raise the hoist with the rated load aboard.  The oil pressure wouldn't be higher than the air pressure unless compounding cylinders are in play.

[F&J]

I forgot the pic of the safety pole:

 

[SC38dls]

As an extra precaution put 4 tall jack stands  under it one at each corner. Then if it comes down all you have to do is fall down too!  Just don’t use HF jack stands. 

[Frank DuVal]

1 hour ago, SC38dls said:

 Just don’t use HF jack stands. 

Because? Their hoist stands are made different than their jack stands. I use three of them with my two post lift. Waaaay better than those Pogo Stick types. 

[Pfeil]

1 hour ago, rocketraider said:

Don't most of these have a safety lever on the guide ram that's supposed to be set once the main ram is fully extended? 

 

Granted, a two-post is an improvement but a lot of those are hydraulic, and use smaller cylinders than a big in-floor lift. And you still have to engage the safety latches.

 

I'm leery of cable-driven electric lifts. Cables stretch and break.

Most of the one's I've used have a rack and pinion guide sleeve next to and goes up with the ram. As soon as the lift goes up the spring loaded lock goes into the rack and in order to get the rack down the lock jam needs to be relieved before pressure comes off. If you loose pressure ( air or Hydraulic) the lift goes down and the spring loaded lock jams the rack stopping it. WEAVER brand is what I used.

 All hoist that I have worked with in over 60+ years have some type of locking safety devise. It's only when people disable the systems is when a disaster happens.

 The only time I have seen trouble is with old cylinders and hydraulic tanks that were put directly in the ground and the metal of the above reacts with the earth causing leaks. Whenever my shop had a leak and new rams- tanks are installed the parts are encased in plastic heavy bags and pea gravel is used to fill around them and then concrete is poured in. The plastic bag protects the environment from a contamination from leakage and also keeps the cylinders from contact with the earth which rust them out.

 Where I lived at the time the state inspected hoist, and heaven forbid they detected a leak on old system without the bag because it becomes a Hazmat issue.

 

 My two above ground four post lifts I have at home are electric/hydraulic and have locks on every post. 

 

Edited November 1, 2021 by Pfeil (see edit history)