[Shop-talk] air over hydraulic bottle jacks

[Steven Trovato]

Randall,

I don't think it works like that.  I have an air over hydraulic floor 
jack, and when I was shopping for it, I was thinking the way you 
are.  But the way it works is that there is a sort of a pump that is 
run by air, but it pumps hydraulic fluid.  It basically provides two 
ways to pump the hydraulic fluid, the manual handle and the air motor 
driven hydraulic pump.  One effect of this is that in use, it makes 
an air tool sort of noise.  Not the sort of silent glide you would 
get if the air was directly raising the jack.  Now, I'm not familiar 
with the particular Harbor Freight jack mentioned here.  If you go to 
the page linked earlier, and look at the manual, you can see the 
parts diagram.  I get the impression that it does work the same way 
my floor jack does.

-Steve Trovato
strovato at optonline.net


At 05:41 PM 10/30/2008, Randall wrote:
> > I got the same (type) jack for the same purpose last year.
>
>So, what happens when what you are pressing on breaks loose ?  Does the ram
>then extend all the way as the air expands ?
>
>Also, I assume that silver cylinder starts out full of hydraulic fluid,
>which gets displaced by the air.  How does it get refilled for the next
>time?