Hydro-Pneumatic Bed Crane

[joshs1ofakindxj]

Seeing all the threads on here about different bed cranes got me hunting the local craigslist for one. I think I got lucky and I scored this heavy duty looking Stratton hydro-pneumatic bed crane for $150. I had to drive an hour and meet a guy at 1am after he got off work to get it but I think it's worth it. Hopefully I can get it working this weekend. It has a big, heavy base with a nice swivel mount. I hope to get the puppy mounted and running off the truck's air supply asap.

Pictures tomorrow, this is just a teaser!

 

[joshs1ofakindxj]

Pictures attached!

Is that one sweet unit or what?

It looks like air comes in the rubber hose to the hand valve, and then air is sent to the fluid reservoir on the back of the arm, and pushes on the hydraulic fluid there. It looks like a discharge air line runs down to the base from the hand valve and there is only one hydraulic port on the cylinder so power up only. Hopefully it works once I put an air line to it tomorrow!

The guy I got it from bought it as-is from a garage where it was just sitting around and he never used it, so I think it was worth the gamble on it needing some mild repairs at the price.

There is no model number, but there is a serial number. I think it looks too nice to be home made. I found a lot of manual bottle jack engine hoists when I searched for similar items from the same company but nothing like this one.

It is 63" tall and the boom is 53" long in the position in the pictures.

 

[silverstate55]

That's a pretty cool find! If it is air operated, then it will work pretty well when it's connected to your Deuce's air supply...it will definitely help you "work smarter, not harder."

Congrats, nice score!

 

[joshs1ofakindxj]

The only downside I see is the truck has to be running, but I don't really call that a downside. The truck likes idling more than anything else!

 

[joshs1ofakindxj]

It works! There some leaks that need address but I might have a winner here. Lift height is 73" max. I'll have to put a limiting strap on it for use under a cargo cover.

Video of it working:

http://youtu.be/uImWhST2a3g

 

[Speedwoble]

Looks like it should be handy. I don't see why they wouldn't have just done a pneumatic cylinder if it functions as you describe. Pressurizing oil with 90 psi air gets you 90 psi oil. Any idea what the capacity is?

 

[mikey]

Can you post the model# of that unit? I'd like to see if I can find one on the web.


That is a he!! of a find. I've been toying with the idea of a bed crane for a year, but I've been considering a 10k electric winch in the bed. Using the deuce air would be awesome. Thanks for the thread!

Mikey

 

[m16ty]

Looks like it should be handy. I don't see why they wouldn't have just done a pneumatic cylinder if it functions as you describe. Pressurizing oil with 90 psi air gets you 90 psi oil. Any idea what the capacity is?

That's what I'm thinking. At first I thought it worked like an air jack (air motor running a hyd pump) but it looks as this one just pressurizes a oil tank that forces oil to move the cylinder. I can't watch the vid (says I need some sort of plug in) so maybe that would give a better idea of how it works.

If this is the case you could just use air without the mess of the oil. A air operated lift is not very stable though. Air will compress (unlike oil) and make the lifting very erratic.

 

[quickfarms]

Due to the compressibility of air the item being lifted would bounce up and down but if you use the air to move the oil the load would not move once the valve is closed. There could be a check valve to control the load.

 

[m16ty]

Due to the compressibility of air the item being lifted would bounce up and down but if you use the air to move the oil the load would not move once the valve is closed. There could be a check valve to control the load.

You could be right if there is some sort of valving to control the oil. I still tend to think it would be kind of erratic while in motion. It will still beat heaving stuff up into the bed by hand though.

 

[59apache]

Looks like it should be handy. I don't see why they wouldn't have just done a pneumatic cylinder if it functions as you describe. Pressurizing oil with 90 psi air gets you 90 psi oil. Any idea what the capacity is?

i guess cause air is compressible, liquids are not. if you lift something, close the valve, the crane is stable with hydraulik. with air not, if you add more load with a hoist or a winch, the arm goes down.




ps: dxxxmn, i'm typing to slow....3 good answers while i'm typing.....

PS: may it acts like a pressure intensifier..90PSI on a big piston to ??PSI on smaller piston with less volume.

 

[joshs1ofakindxj]

Can you post the model# of that unit? I'd like to see if I can find one on the web.


That is a he!! of a find. I've been toying with the idea of a bed crane for a year, but I've been considering a 10k electric winch in the bed. Using the deuce air would be awesome. Thanks for the thread!

Mikey

Unfortunately, there i nothing stamped on the data plate where the model # should be. Just a serial number.

 

[joshs1ofakindxj]

That's what I'm thinking. At first I thought it worked like an air jack (air motor running a hyd pump) but it looks as this one just pressurizes a oil tank that forces oil to move the cylinder. I can't watch the vid (says I need some sort of plug in) so maybe that would give a better idea of how it works.

If this is the case you could just use air without the mess of the oil. A air operated lift is not very stable though. Air will compress (unlike oil) and make the lifting very erratic.

I uploaded the video to youtube so you can see it without a plug in

Stratton Hydro-Crane - YouTube

 

[joshs1ofakindxj]

It looks like it has a 3 position hand valve. Up, neutral or hold, and down. There seems to be some leaking coming from the valve so it is the first thing I'm going to disassemble, clean and inspect.

 

[Speedwoble]

i guess cause air is compressible, liquids are not. if you lift something, close the valve, the crane is stable with hydraulik. with air not, if you add more load with a hoist or a winch, the arm goes down.

ps: dxxxmn, i'm typing to slow....3 good answers while i'm typing.....

PS: may it acts like a pressure intensifier..90PSI on a big piston to ??PSI on smaller piston with less volume.

Agreed with all who stated this. However, I did not see a valve between the "air chamber" and hydraulic cylinder, so there is no way to lock it. The only valve is at the top of the air chamber.

Josh, any idea of max lift?
I'm estimating a 4" hydraulic cylinder. At 90psi, that's just shy of 1200lbs force at the cylinder. 1ft from pivot to cylinder, then 3 ft from cylinder to hook point. ~300lb load.

 

[joshs1ofakindxj]

No idea on what it can lift. Once it is bolted down in the back of the deuce bed, testing will follow.

If I find it to be insufficient, it won't take much to add a harbor freight bottle jack to it and remove all of the air lift components. It would be a shame to carve up a cool bed crane like this, so I hope I don't have to go that route.

 

[joshs1ofakindxj]

The air valve came apart easily and looks to be pretty well worn inside.

As suspected it looks like it supplied air, blocked air and held it in the system, and released air in the 3 positions of the lever.

I think I'm going to replace the whole air switch with some simple plumbing and 2 ball valves.

One will be air in from the truck, one will be air out. When both are closed the air in the system will be held.

 

[joshs1ofakindxj]

I did some simple plumbing, filled the reservoir with ATF, greased the base, and adjusted the orifice on the lower line that controls speed to make it nice and slow lifting.

I like it!

I thought it was ready for paint and mounting then testing BUT I found out it needs shortened about 4" to fit under my cargo cover. I'll try to work on that tomorrow.

 

[southbreeze]

Josh, that's a cool ol' school, simplistic, sooper cool crane you got there. The air over hydraulics, gives you the best of both worlds, gives you the speed of function without the cost of a Hydraulic Power Unit.

The air power tends to be easier on the hardware because there is some measure of "cushion or float" between the two. It's the same principle of Motion Compensation that we use in deepwater drilling. We use up to 2300psi air over hydraulic oil to carry as much as 900,000 lbs of drillstring weight. you can imagine bobbing up and down on a boat in the waves, the rigs do the same thing. So by setting the air pressure relative to the weight on bit, the bit will hold the same position as the rig heaves up and down with the sea state.

If the inside diameter of the reservoir is larger than the outside diameter of the piston, the yes the reservoir is a pressure intensifier. Personally, I wouldn't worry about the function being erratic because of the air.

Now for warning, I see your ball valves in the last pic's, know that these valves aren't designed for finite control. Also that pneumatics differ greatly in power to pressure to work than hydraulics. Hydraulic is linear in nature, pneumatics are exponential in nature. They go from very little motion to ripping the doors off very rapidly.

Sorry, didn't mean to get on the techno soapbox. Cool looking crane that won't have the operating cost of the new fangled hydraulic stuff.

Cheers,
Breeze

Presently employed as a Rig based Chief Engineer

 

[southbreeze]

one more thing, its a reminder of the russian admonition of the US for spending millions of dollars developing a pen that will write in outer space......they just used a pencil.

Old school cool without all the "i-pod/phone/pad/book/whatever" BS!

Cheers,
Breeze