Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Old May 20th 11, 02:32 AM posted to rec.crafts.metalworking
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Default 5000 lbs crane on a 3/4 ton pickup

On Thu, 19 May 2011 09:08:16 -0400, "Ed Huntress"
wrote:


"john B." wrote in message
.. .
On Wed, 18 May 2011 19:09:01 -0500, Ignoramus15557
wrote:

Guys... I am not talking to anyone specifically right now... I sense a
little bit of B/S on this topic.

Right now, I have a crane that lifts 500 lbs, mounted on a 1x1 foot
plate, with angle iron underneath the bed holding it in [place with
thru bolts. While it is slightly shaky, it works just fine.

With this Ramco crane, I am going to have a crane that would lift
about twice more weight -- 1k lbs -- supported by a 3x4 foot
plate. That is 12 times more area than the 1x1 foot plate! Even if it
is not evenly distributed across the plate, it is still a hell of a
lot more support and weight distribution than a 1x1 foot plate.

I think that I will be just fine with it without fabricating any funky
adapters and bolting them to the frame.

i

I don't know the weight of your 5,000 lb. capacity crane or your
plate, but assuming that your plate is 3/4" and the crane weighs 500
lbs then you have a maximum weight of components plus load of 5,868
lbs. divided by 1728"2 = ~3.4 psi.

I just measured the area of one foot and weighed myself. If I stand on
one foot in the back of your pickup I will exert a force of ~5.36 psi.


I haven't followed this and I may have missed this point, but I would think
that the issue here is not transferring the load evenly to the area of the
plate, but rather the effect of the lever arm, with the weight loaded some
distance from the center of the vertical column. That's what I'm picturing
as the "crane," anyway.

And if that's the case, then the specific load on the edges of the plate can
be many, many times the force of lifting the load.



There were all kinds of arguments going on. Mash the sheetmetal, etc.

But you are correct, the limits to crane operation are usually tipping
moments, not actual maximum lifting capacity as that is usually
specified with the boom at 89 degrees.


  #32   Report Post  
Old May 20th 11, 03:01 AM posted to rec.crafts.metalworking
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Posts: 12,529
Default 5000 lbs crane on a 3/4 ton pickup


"john B." wrote in message
...
On Thu, 19 May 2011 09:08:16 -0400, "Ed Huntress"
wrote:


"john B." wrote in message
. ..
On Wed, 18 May 2011 19:09:01 -0500, Ignoramus15557
wrote:

Guys... I am not talking to anyone specifically right now... I sense a
little bit of B/S on this topic.

Right now, I have a crane that lifts 500 lbs, mounted on a 1x1 foot
plate, with angle iron underneath the bed holding it in [place with
thru bolts. While it is slightly shaky, it works just fine.

With this Ramco crane, I am going to have a crane that would lift
about twice more weight -- 1k lbs -- supported by a 3x4 foot
plate. That is 12 times more area than the 1x1 foot plate! Even if it
is not evenly distributed across the plate, it is still a hell of a
lot more support and weight distribution than a 1x1 foot plate.

I think that I will be just fine with it without fabricating any funky
adapters and bolting them to the frame.

i
I don't know the weight of your 5,000 lb. capacity crane or your
plate, but assuming that your plate is 3/4" and the crane weighs 500
lbs then you have a maximum weight of components plus load of 5,868
lbs. divided by 1728"2 = ~3.4 psi.

I just measured the area of one foot and weighed myself. If I stand on
one foot in the back of your pickup I will exert a force of ~5.36 psi.


I haven't followed this and I may have missed this point, but I would
think
that the issue here is not transferring the load evenly to the area of the
plate, but rather the effect of the lever arm, with the weight loaded some
distance from the center of the vertical column. That's what I'm picturing
as the "crane," anyway.

And if that's the case, then the specific load on the edges of the plate
can
be many, many times the force of lifting the load.



There were all kinds of arguments going on. Mash the sheetmetal, etc.

But you are correct, the limits to crane operation are usually tipping
moments, not actual maximum lifting capacity as that is usually
specified with the boom at 89 degrees.


Yeah, I just saw the photo of it. The load on bolts holding a supporting
plate under the bed itself will be reduced considerably by using a larger
plate.

--
Ed Huntress



  #33   Report Post  
Old May 20th 11, 04:17 AM posted to rec.crafts.metalworking
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Posts: 6
Default 5000 lbs crane on a 3/4 ton pickup

On 2011-05-20, Ed Huntress wrote:

"john B." wrote in message
...
On Thu, 19 May 2011 09:08:16 -0400, "Ed Huntress"
wrote:


"john B." wrote in message
...
On Wed, 18 May 2011 19:09:01 -0500, Ignoramus15557
wrote:

Guys... I am not talking to anyone specifically right now... I sense a
little bit of B/S on this topic.

Right now, I have a crane that lifts 500 lbs, mounted on a 1x1 foot
plate, with angle iron underneath the bed holding it in [place with
thru bolts. While it is slightly shaky, it works just fine.

With this Ramco crane, I am going to have a crane that would lift
about twice more weight -- 1k lbs -- supported by a 3x4 foot
plate. That is 12 times more area than the 1x1 foot plate! Even if it
is not evenly distributed across the plate, it is still a hell of a
lot more support and weight distribution than a 1x1 foot plate.

I think that I will be just fine with it without fabricating any funky
adapters and bolting them to the frame.

i
I don't know the weight of your 5,000 lb. capacity crane or your
plate, but assuming that your plate is 3/4" and the crane weighs 500
lbs then you have a maximum weight of components plus load of 5,868
lbs. divided by 1728"2 = ~3.4 psi.

I just measured the area of one foot and weighed myself. If I stand on
one foot in the back of your pickup I will exert a force of ~5.36 psi.

I haven't followed this and I may have missed this point, but I would
think
that the issue here is not transferring the load evenly to the area of the
plate, but rather the effect of the lever arm, with the weight loaded some
distance from the center of the vertical column. That's what I'm picturing
as the "crane," anyway.

And if that's the case, then the specific load on the edges of the plate
can
be many, many times the force of lifting the load.



There were all kinds of arguments going on. Mash the sheetmetal, etc.

But you are correct, the limits to crane operation are usually tipping
moments, not actual maximum lifting capacity as that is usually
specified with the boom at 89 degrees.


Yeah, I just saw the photo of it. The load on bolts holding a supporting
plate under the bed itself will be reduced considerably by using a larger
plate.


So, Ed, what is the implication for what I am trying to do?

i
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Old May 20th 11, 04:18 AM posted to rec.crafts.metalworking
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Posts: 6
Default 5000 lbs crane on a 3/4 ton pickup

On 2011-05-20, justme wrote:
I think, better still, is put the plate beneath the frame as bolts
could pull out if bolted on top.


Not if I use backing plates.

i

Joe

On Tue, 17 May 2011 22:22:52 -0400, "ATP"
wrote:


"Ignoramus31865" wrote in message
om...
On 2011-05-18, Pete C. wrote:

Ignoramus31865 wrote:

I have a GM 3/4 ton pickup.

I won, in an auction, a "Ramco RM5000" crane. This crane is similar to
the Harbor Freight truck crane, but is a lot beefier.

It is pictured he

http://igor.chudov.com/tmp/Ramco-RM5000-Truck-Crane.jpg

(not mine, but an identical model).

This is rated for 5k pounds, I am sure for the boom fully retracted.

It has a 8,000 lbs jack. I will put in a longer boom too, and a
winch. I am aware that extending the boom will decrease capacity
proportionally, so a boom that is 4 foot would decrease capacity of
the crane to, say, 1,500 lbs or whatever. I have to call the mfr to
find out. This is stillw ay better than my HF crane.

I have a very large 3/4 inch steel plate, I would say 3x4 feet, that
is rusting in my backyard.

What I thought of doing, is making a cutout on the plate to fit around
a wheel well, and mount it in the back of the truck's bed, and put the
crane on top of it. The Ramco crane would sit in the rear right corner
of the bed, just like this Harbor Freight crane does now:

http://goo.gl/KAN0Y

It has to be a large plate, to spread the weight of the crane and the
levering action that its base would apply to the bed. This particular
plate weighs around 300 lbs and is large enough.

My question is, what sort of constraints do I still have. I would hate
to overturn my truck, break suspension, etc. I would also think that
for heavy lifting, I would need to jack up the right rear wheel too.

Any practical opinions?

i

A crane with that weight capacity really needs to be mounted to the
frame, not to pickup bed sheetmetal. I think typically it would be
mounted with a beefy bracket under the bed to the frame. A support leg
(trailer jack) for the corner of the truck with the crane is common for
the heavier cranes so you don't apply a concentrated load to the
suspension on one side of the truck and also to stabilize it so it stays
level during the lift instead of tilting to that side.

What I was going to do is put a steel plate, 3x4 feet or so, on the
bed and bolt it to the bed. Would that not be enough support for the
crane? I already have this plate and it is huge.

i


The bed is probably not more than 18 gauge, right? Plus as soon as you put
that plate on top it will rust out fast. Pete is right, also don't weld the
bracket to your frame, bolt it.

  #35   Report Post  
Old May 20th 11, 05:01 AM posted to rec.crafts.metalworking
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Posts: 12,529
Default 5000 lbs crane on a 3/4 ton pickup


"Ignoramus27965" wrote in message
news
On 2011-05-20, Ed Huntress wrote:

"john B." wrote in message
...
On Thu, 19 May 2011 09:08:16 -0400, "Ed Huntress"
wrote:


"john B." wrote in message
m...
On Wed, 18 May 2011 19:09:01 -0500, Ignoramus15557
wrote:

Guys... I am not talking to anyone specifically right now... I sense a
little bit of B/S on this topic.

Right now, I have a crane that lifts 500 lbs, mounted on a 1x1 foot
plate, with angle iron underneath the bed holding it in [place with
thru bolts. While it is slightly shaky, it works just fine.

With this Ramco crane, I am going to have a crane that would lift
about twice more weight -- 1k lbs -- supported by a 3x4 foot
plate. That is 12 times more area than the 1x1 foot plate! Even if it
is not evenly distributed across the plate, it is still a hell of a
lot more support and weight distribution than a 1x1 foot plate.

I think that I will be just fine with it without fabricating any funky
adapters and bolting them to the frame.

i
I don't know the weight of your 5,000 lb. capacity crane or your
plate, but assuming that your plate is 3/4" and the crane weighs 500
lbs then you have a maximum weight of components plus load of 5,868
lbs. divided by 1728"2 = ~3.4 psi.

I just measured the area of one foot and weighed myself. If I stand on
one foot in the back of your pickup I will exert a force of ~5.36 psi.

I haven't followed this and I may have missed this point, but I would
think
that the issue here is not transferring the load evenly to the area of
the
plate, but rather the effect of the lever arm, with the weight loaded
some
distance from the center of the vertical column. That's what I'm
picturing
as the "crane," anyway.

And if that's the case, then the specific load on the edges of the plate
can
be many, many times the force of lifting the load.


There were all kinds of arguments going on. Mash the sheetmetal, etc.

But you are correct, the limits to crane operation are usually tipping
moments, not actual maximum lifting capacity as that is usually
specified with the boom at 89 degrees.


Yeah, I just saw the photo of it. The load on bolts holding a supporting
plate under the bed itself will be reduced considerably by using a larger
plate.


So, Ed, what is the implication for what I am trying to do?

i


I've skipped many messages in this thread so I can still be missing
something. Figure out the actual loads at the bolts, Iggy. If you don't do
statics, it's worth looking it up online. For the things you do, it will
eventually be invaluable. It's essential for all kinds of custom rigging
jobs.

From that, figure out how much load you'll be putting on the bolts that pass
through the sheet metal of the bed. Unless there is some more metal there, a
plate *underneath* the bed won't help a bit in dealing with the forces
trying to pull the bolts down through the sheetmetal when you load the
crane. What you need to be concerned about is how much to distribute the
load on *top* of the bed, on the bolts that are trying to pull down through
it.

A larger plate will help, not because it distribute the load, but because
the lever arm from the base of the column to the farthest bolts in the plate
will be longer and the forces will be proportionally lower.

You're a math guy so this isn't really a concern, but for most people, a
book on statics and dynamics written for technicians (like two-year college
program students) is a lot easier to deal with than one written for
engineers. The math is all pre-calculus that way. I have such a book and I
still refer to it from time to time.

--
Ed Huntress




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Old May 20th 11, 01:05 PM posted to rec.crafts.metalworking
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Default 5000 lbs crane on a 3/4 ton pickup

On May 19, 11:01*pm, "Ed Huntress" wrote:
...
A larger plate will help, not because it distribute the load, but because
the lever arm from the base of the column to the farthest bolts in the plate
will be longer and the forces will be proportionally lower.

You're a math guy so this isn't really a concern, but for most people, a
book on statics and dynamics written for technicians (like two-year college
program students) is a lot easier to deal with than one written for
engineers. The math is all pre-calculus that way. I have such a book and I
still refer to it from time to time.
Ed Huntress-


Harry Parker's "Simplified Design of..." books for structural steel
and timber:
http://www.amazon.com/Simplified-Des.../dp/0471664324

My problem with engineering textbooks is the lack of instructor
feedback if I misunderstand something.

jsw
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Old May 20th 11, 02:10 PM posted to rec.crafts.metalworking
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Default 5000 lbs crane on a 3/4 ton pickup

On May 19, 11:01*pm, "Ed Huntress" wrote:
...
A larger plate will help, not because it distribute the load, but because
the lever arm from the base of the column to the farthest bolts in the plate
will be longer and the forces will be proportionally lower.
--
Ed Huntress-


I drilled a hole in the top of the crane's vertical post, to store the
pump handle, which provides a guy line attachment for a cable to the
bed tie-downs or a nearby tree when I winch logs out of tangled piles.
I ruined a 1200 Lb boat trailer winch doing that, though better the
winch than the truck if I'd used an electric winch with no feel.

The rear bed bolts aren't far enough apart fore-aft to attach a large
base frame. When I lift a max load behind the truck the front crossbar
bends up from the leverage. I could reinforce it but it's a good
visible indicator of overload.

jsw
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Old May 20th 11, 02:15 PM posted to rec.crafts.metalworking
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Default 5000 lbs crane on a 3/4 ton pickup


"Jim Wilkins" wrote in message
...
On May 19, 11:01 pm, "Ed Huntress" wrote:
...
A larger plate will help, not because it distribute the load, but because
the lever arm from the base of the column to the farthest bolts in the
plate
will be longer and the forces will be proportionally lower.
--
Ed Huntress-


I drilled a hole in the top of the crane's vertical post, to store the
pump handle, which provides a guy line attachment for a cable to the
bed tie-downs or a nearby tree when I winch logs out of tangled piles.
I ruined a 1200 Lb boat trailer winch doing that, though better the
winch than the truck if I'd used an electric winch with no feel.


Aha. So you made a gin pole out of it. Good idea.


The rear bed bolts aren't far enough apart fore-aft to attach a large
base frame. When I lift a max load behind the truck the front crossbar
bends up from the leverage. I could reinforce it but it's a good
visible indicator of overload.

.jsw


This is what has been in my mind as I think about Iggy's application.

--
Ed Huntress


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Old May 20th 11, 02:54 PM posted to rec.crafts.metalworking
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Default 5000 lbs crane on a 3/4 ton pickup

On May 20, 8:13*am, "Ed Huntress" wrote:
"Jim Wilkins" wrote in message
...
Yes! From decades of self-teaching, I can suggest my own solution: two or
three books, written by different authors, that explain the same thing in
different ways. ...

Ed Huntress


I've found that I need an intuitive explanation first to provide a
framework to file away the subsequent formulaic ones, which killed me
when I got to Laplace Transforms.

Unfortunately some good mathematicians have a limited ability to think
visually. My first physics teacher couldn't look at a sign support on
the front of a building and tell whether the diagonal brace was in
tension or compression. He had to solve the algebra and see the sign
of the result. A girlfriend's father who taught physics had quit
chemistry because he couldn't imagine the 3 dimensional molecular
structures.

She was a lovely, classy lady who didn't help me concentrate on math
and molecules either.

jsw
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Old May 20th 11, 03:10 PM posted to rec.crafts.metalworking
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Default 5000 lbs crane on a 3/4 ton pickup

On May 20, 8:15*am, "Ed Huntress" wrote:
"Jim Wilkins" wrote in message
... I drilled a hole in the top of the crane's vertical post, to store the
pump handle, which provides a guy line attachment for a cable to the
bed tie-downs or a nearby tree ...


Aha. So you made a gin pole out of it. Good idea.

This is what has been in my mind as I think about Iggy's application.

Ed Huntress


The extra support doesn't add much total lifting capacity as the stake
pockets are just sheet metal and would be difficult to hammer back to
shape if damaged. The one-sided load on the leaf spring doesn't
change. I made an extension post for tall bulky loads like appliances
which stress the crane base from longer leverage rather than weight,
and benefit from the guy lines.

jsw


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