Overloading a hydraulic jack....

[kunkernator]

What happens when you overload a jack? Like if you use a small 1.5 ton jack on a huge pickup truck. Will it fail catastrophically? Or will it just not lift? Or slowly fall?

I am asking this just for curiosity. I may be getting a larger vehicle soon, so I may need to purchase a new jack.

Thanks guys, and merry Christmas!

 

[darkk]

All the oil comes out and you end up with your own personal mini Exxon Valdez.

 

[Davo J]

It will be really hard to pump and once at it's load capacity or just over the bypass valve will open up and the jack wont go up.

Dave

 

[ex-x-fire]

If its an old USA jack its probably underated. My new 40yr old walker is rated at 1.5 ton, it'll lift things alot easier then my 5yr (now broken) 3.5 ton china jack.

 

[kunkernator]

Alright, thanks for the info. I just was always curious what would happen. Leaking oil is a lot better than the thing collapsing. So the actual structure of the jack is stronger than the hydraulic cylinder.

 

[toddacimer]

Several things may happen, you could see leaking around the pump shaft of the jack, the handle may get very hard to pump, if you use a hydraulic Jack as a jack stand and transfer the load from 1 jack to another of a lesser rating you could blow out the main piston seal causing the jack to drop. Ultimately I wouldn't recommend over loading a hydraulic jack, not even a little bit.

 

[bad_idea]

Got a cheap one you don't need? Got a hydraulic press (rated higher than the jack)? Use the press to overload the jack and see what happens! Film it. I'd like to see that. Put a cage around it though just to be safe.

 

[toddacimer]

Got a cheap one you don't need? Got a hydraulic press (rated higher than the jack)? Use the press to overload the jack and see what happens! Film it. I'd like to see that. Put a cage around it though just to be safe.

That's a good way to over pressurize the main ram seal on the jack shaft. There's a good chance the seal will fail and the jack will drop very quickly.

 

[Monte]

cheap jacks often don´t have a overload protection ....

 

[kunkernator]

cheap jacks often don´t have a overload protection ....

That is good info. So if a cheap jack fails it won't just let down? Will the cylinder rupture?

 

[toddacimer]

That is good info. So if a cheap jack fails it won't just let down? Will the cylinder rupture?

The seal will probably let go causing the jack to drop almost instantly

 

[Ironhorse]

yea...well I can not speak for most...but my hotrods are low to the ground so I grabbed one of my BRUNNHOELZL race jacks 3 pump low profile...slid it under the car got two pumps in and it bent the lifting arm...it was a 1 ton I think they are not marked...so guess what??? I do not do that anymore..lol. The ram and base were fine...the arm was f#$% up...and thank god the car was fine...I was more worried about the car then the jack..it came down pretty quick..

 

[greasemonkey44]

even the cheap ones have overload valves
usually they will either have way too much presure to overcome to pump it or (if you are all the way up ) it will just dump the excess
i did flex the **** out of my 1.5 ton HF aluminum one; its fine but the wheels need to roll for it to work right

 

[Hiball]

cheap jacks often don´t have a overload protection ....

Not Exactly True...

If its an old USA jack its probably underated. My new 40yr old walker is rated at 1.5 ton, it'll lift things alot easier then my 5yr (now broken) 3.5 ton china jack.

From a PSI standpoint, a 1.5 ton Walker is More than capable of producing the PSI to lift more than a 3000lbs. Now.. from a liability standpoint, you wont easily find a Hydraulic shop that will set the Overload to exceed the Manufacturers rating. Todays consumers are obsessed with Numbers, Whether its 4 ton small frame floor jacks or 10Hp push mowers. The Cylinder Bore size between your prototypical 3.5 ton Import is only 1/8" bigger than a Walker 1.5 ton floor jack.