what is this hydraulic thing called?

[xymotic]

Hi everyone. I bought a couple Semi Trailer Hydraulic landing gear units that I'd like to use for some other projects.

Initially I thought these were electrically operated, but in looking closer I guess that they are air-over hooked to the truck's brake system??

anyway, in trying to figure out how to use these parts, I haven't been able to find a unit similar to this one and I'm wondering if anybody knows what it's called? it seems like basically a simple ram except maybe a one way ball valve deal in the top.

I'd like to use the legs for a shop press and maybe a wood splitter, but I'm just unsure of what sort of capacity this part might have to drive it all.

 

[Sumboodie]

I've never seen anything like that on a semi trailer. Can't say I've seen ALL trailers of course, but been around many van, flatbed, lowboy, open top (wood chip), Conestoga, refers, step deck, etc. It must be fairly specific to a brand of trailer or for a specific function.

 

[kaymccampbell]

I've heard it called a master cylinder or a power cylinder. I doubt it would make a good hydraulic cylinder. The big end is typically for low pressure truck brake air.

 

[Firebrick43]

They are basically intensifiers. They take 120 air brake pressure on the large piston and transfer that force on the small piston to build higher hydraulic pressure. The valves actuate the air cylinder back and forth.

To figure the force on the air side take 120 psi and multiply it by the area of the large piston. Then to figure the hydraulic pressure divide that number by the area of the small side.

Most trailers now that have hydraulic functions use trucks with a wet kit(hydraulic pump).

It wasn’t common but air over hydraulic was used years ago.

 

[matt_i]

I can't see your pics but based on air over hydraulic or "active" intensifiers, they generally need a lot of air...which isn't cheap....

 

[xymotic]

thanks everyone. I've found various intensifiers just none of them looked like this. I will likely replace it with a pump just trying to wrap my brain around how it's all setup. The Seller told me these were standard on all UPS trucks, dunno how old it is but I'm guessing woulda been 1st gen type system. only thing I could find on the MFT is that they went bankrupt in the 90's.

but for the $100 the guy was asking for two legs a pressure tank three valves and this doohicky I figgured it was worth a shot

 

[billspit]

All I see is a great big minus sign.

 

[gnpenning]

All I see is a great big minus sign.

Yep.

 

[KenC]

All I see is a great big minus sign.

You're lucky, I don't even see that!