[TheForge] HF 20 Ton Air Motors Jacks

[Jerry Frost]

Vince: How long was the crane arm and where was the jack mounted? The
leverage ratio is what I'm wondering about. I have an engine hoist that has
a max rated lift of 1,000lbs. with the boom retracted all the way and is
pushed with a 12ton. Manual hydraulic long shaft jack. Fully retracted the
boom is 5' from the jack ears to the chain and it's 6" from the jack ear to
the boom hinge ear. The leverage ratio being 10:1. It's an American made
engine hoist so has a reasonable safety factor as does the jack and all the
fabrication.

And that's why I'm wondering about your crane's leverage ratio. For a 12 ton
jack to lift 12 tons it'd have to have a 1:1 ratio and no safety factor or
something less, a 1/x:1 ratio.

Just thinking and wondering.

Jer

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Vincent Nakovics
Sent: Sunday, March 9, 2014 9:35 AM
To: theforge at mailman.qth.net
Subject: Re: [TheForge] HF 20 Ton Air Motors Jacks

Hi Guys,
    My experience with the one that I had went something like this. I used a
20 Ton Air over jack or motor, you know, and I also bought a 12 ton frame
from HF. It was an experiment and I really didn't think the jacks would put
out a true 20 ton. I believe it will put out 20 ton but that it is at the
absolute maximum of it's capacity. I base this on the long ram 12 ton used
with a 6 Ton shop crane unit. I will get to that in a minute. The 20 ton air
over did bend the 12 ton frame, I added braces after seeing a slight bend to
reinforce the top cross bar. After reinforcing it I never had a problem with
it bending again. I did find that it really didn't have enough umph to do
any real squashing. I intended on using it to flatten large rivet heads, but
I felt that I could do it faster and easier by hand. 
     
      In comparison to my Electric drive Dake 25 Ton press, the 20 ton Air
over jack paled. It could not cold punch past 3/16" though at 20 tons it
should have been able to do 1/4". I may have done the math wrong, but the
chart from some company on my office wall said the same. The 20 ton did hold
pressure over night as I used it a few times to compress materials and to
hold a couple of items together while the JB weld or glue set and hardened.
For the money I was satisfied and had plans to use it for other things
besides squashing rivet heads (1-1/8" Dia x 1" Ht).

  There is my experiment and comparison. Not scientific as I had only one of
each to compare, but it is a comparison. 

Now for the crane story.
   
The 12 ton air
over long ram I installed on a crane rated for 6 tons that had an 8 ton hand
pump jack on it. I found that past 1/2 the length of the ram it strained at
just over 6 tons. The test weight was 6,041lbs. Oh the HF crane started to
buckle at the pressure point where the ram lifted. 
Reinforcement time, just to be safe. I never lifted that much weight again.
I did lift regularly 5,750lbs. and the air jack did lift it, but slowly. I
doubt it would lift 12 tons, but certainly it lifted 6 just fine, never got
a heavy enough crane rig to test for more. For the money I was happy with
its performance. 

That's my story.

See ya at the Forge!
Vince Nakovics
 
"It was done that way by the Master before, and the one before him, What
need to write it down?"

http://www.createspace.com/4515785
www.happyhavenforge.wordpress.com