Estimating wooden ramp strength
 

I have steel ramps, but they are very short and suitable for my [low]
trailer only.

I am considering making ramps from wooden boards. Specifically,
picture a ramp that looks like a letter I in cross section. The wide
part of the I is a 2x8. On the top and bottom of the I, there would be
2x4s. The "I", of course, would be laid flat for use.

Here's the ascii graphic:

.. .
|==========|
~ ~

The 2x4s would be screwed to the 2x8 with wood screws, and reinforced
with glue.

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).

thanks

i

Estimating wooden ramp strength
 

Ignoramus20839 wrote:
I have steel ramps, but they are very short and suitable for my [low]
trailer only.

I am considering making ramps from wooden boards. Specifically,
picture a ramp that looks like a letter I in cross section. The wide
part of the I is a 2x8. On the top and bottom of the I, there would be
2x4s. The "I", of course, would be laid flat for use.

Here's the ascii graphic:

. .
|==========|
~ ~

The 2x4s would be screwed to the 2x8 with wood screws, and reinforced
with glue.

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).

It is simply a 3x3-1/2 beam for estimating purposes. You can forget the
2x8 in the horizontal as it is conservative to do so.

I don't have a link ottomh, but a google will find any number of beam
deflection engines.

Use SYP or fir for higher modulus and, of course, be sure it is
defect-free timber.

Depending on length and weight desired, going w/ 2x6 tapered some for
the ends might be more suitable at the expense of a little more
weight/heft/bulk...

--

Estimating wooden ramp strength
 

"Ignoramus20839" wrote in message
...
I have steel ramps, but they are very short and suitable for my [low]
trailer only.

I am considering making ramps from wooden boards. Specifically,
picture a ramp that looks like a letter I in cross section. The wide
part of the I is a 2x8. On the top and bottom of the I, there would be
2x4s. The "I", of course, would be laid flat for use.

Here's the ascii graphic:

. .
|==========|
~ ~

The 2x4s would be screwed to the 2x8 with wood screws, and reinforced
with glue.

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).

thanks


Two thoughts...

Why not just take the 2 X 8's and test them. Put them on a block of some
kind on the ground and roll whatever you plan to use them for onto them and
observe the deflection. This would be simple and just cost the price of a
couple boards.

I have seen a number of ramps that have a metal end on them specifically
designed for a ramp. I think that would be much more compace and work better
than your proposed 2 X 4 ends. I don't know where to purchase them, but
they are out there because I have seen them in use many times.

Estimating wooden ramp strength
 

Ignoramus20839 writes:

On the top and bottom of the I, there would be
2x4s.

Might be stronger/lighter/cheaper if you attached some steel angle (hidden
at Home Depot on the electrical aisle) to the 2x8, or to slices of a sheet
of 3/4 plywood.

Estimating wooden ramp strength
 

Ignoramus20839 wrote:

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).

Using spruce pine and ignoring the 2x8, the sagulator gives a deflection
of .7" for 500lbs of load in the center of a single 8' ramp.

Chris

Estimating wooden ramp strength
 

On 2007-10-25, Chris Friesen wrote:
Ignoramus20839 wrote:

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).

Using spruce pine and ignoring the 2x8, the sagulator gives a deflection
of .7" for 500lbs of load in the center of a single 8' ramp.


OK, this is great. What does your sagulator say about 1000 lbs load?

also, what would it say if I replaced 2x4s with 2x6s?

I appreciate your help . Thanks a lot.

i

Estimating wooden ramp strength
 

Ignoramus20839 wrote:
On 2007-10-25, Chris Friesen wrote:
Ignoramus20839 wrote:

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).
Using spruce pine and ignoring the 2x8, the sagulator gives a deflection
of .7" for 500lbs of load in the center of a single 8' ramp.


OK, this is great. What does your sagulator say about 1000 lbs load?

Google "sagulator" and experiment to your heart's content...

--

Estimating wooden ramp strength
 

On 2007-10-25, dpb wrote:
Ignoramus20839 wrote:
On 2007-10-25, Chris Friesen wrote:
Ignoramus20839 wrote:

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).
Using spruce pine and ignoring the 2x8, the sagulator gives a deflection
of .7" for 500lbs of load in the center of a single 8' ramp.


OK, this is great. What does your sagulator say about 1000 lbs load?

Google "sagulator" and experiment to your heart's content...


I thought that sagulator was a PC program. It is great! I have it
bookmarked and am now experimenting!!!

Looks like with 2x4x, the deflection of a 1,000 lbs load in the middle
will be about 2 inches, which is too much.

However, with 2x6s, the deflection will only be 0.36 inches, and 0.7
inches with 2,000 lbs center load.

So, it seems, that a ramp made to the shape of letter I, could easily
let me deal with 2,000 lbs wheeled loads. (such as a dolly on casters)

i

Estimating wooden ramp strength
 

Ignoramus20839 wrote:
On 2007-10-25, dpb wrote:
Ignoramus20839 wrote:
On 2007-10-25, Chris Friesen wrote:
Ignoramus20839 wrote:

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).
Using spruce pine and ignoring the 2x8, the sagulator gives a deflection
of .7" for 500lbs of load in the center of a single 8' ramp.

OK, this is great. What does your sagulator say about 1000 lbs load?
Google "sagulator" and experiment to your heart's content...


I thought that sagulator was a PC program. It is great! I have it
bookmarked and am now experimenting!!!

Looks like with 2x4x, the deflection of a 1,000 lbs load in the middle
will be about 2 inches, which is too much.

However, with 2x6s, the deflection will only be 0.36 inches, and 0.7
inches with 2,000 lbs center load.

So, it seems, that a ramp made to the shape of letter I, could easily
let me deal with 2,000 lbs wheeled loads. (such as a dolly on casters)

Well, when you're dealing with that kind of loads, don't forget the
supporting ends, joint strength and fasteners, point loading of a caster
on the 2x ramp, the downward force of the load back down the ramp
running over whatever is in the way, the load limit on a truck tailgate,
etc., etc., etc., ...

--

Estimating wooden ramp strength
 

sOn 2007-10-25, dpb wrote:
Ignoramus20839 wrote:
On 2007-10-25, dpb wrote:
Ignoramus20839 wrote:
On 2007-10-25, Chris Friesen wrote:
Ignoramus20839 wrote:

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).
Using spruce pine and ignoring the 2x8, the sagulator gives a deflection
of .7" for 500lbs of load in the center of a single 8' ramp.

OK, this is great. What does your sagulator say about 1000 lbs load?
Google "sagulator" and experiment to your heart's content...


I thought that sagulator was a PC program. It is great! I have it
bookmarked and am now experimenting!!!

Looks like with 2x4x, the deflection of a 1,000 lbs load in the middle
will be about 2 inches, which is too much.

However, with 2x6s, the deflection will only be 0.36 inches, and 0.7
inches with 2,000 lbs center load.

So, it seems, that a ramp made to the shape of letter I, could easily
let me deal with 2,000 lbs wheeled loads. (such as a dolly on casters)

Well, when you're dealing with that kind of loads, don't forget the
supporting ends, joint strength and fasteners, point loading of a caster
on the 2x ramp, the downward force of the load back down the ramp
running over whatever is in the way, the load limit on a truck tailgate,
etc., etc., etc., ...


Well, absolutely. Plus the 2x8 may crack on the middle under such a
load.

i

Estimating wooden ramp strength
 

Ignoramus20839 wrote:

sOn 2007-10-25, dpb wrote:
Ignoramus20839 wrote:
On 2007-10-25, dpb wrote:
Ignoramus20839 wrote:
On 2007-10-25, Chris Friesen wrote:
Ignoramus20839 wrote:

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).
Using spruce pine and ignoring the 2x8, the sagulator gives a deflection
of .7" for 500lbs of load in the center of a single 8' ramp.

OK, this is great. What does your sagulator say about 1000 lbs load?
Google "sagulator" and experiment to your heart's content...


I thought that sagulator was a PC program. It is great! I have it
bookmarked and am now experimenting!!!

Looks like with 2x4x, the deflection of a 1,000 lbs load in the middle
will be about 2 inches, which is too much.

However, with 2x6s, the deflection will only be 0.36 inches, and 0.7
inches with 2,000 lbs center load.

So, it seems, that a ramp made to the shape of letter I, could easily
let me deal with 2,000 lbs wheeled loads. (such as a dolly on casters)

Well, when you're dealing with that kind of loads, don't forget the
supporting ends, joint strength and fasteners, point loading of a caster
on the 2x ramp, the downward force of the load back down the ramp
running over whatever is in the way, the load limit on a truck tailgate,
etc., etc., etc., ...


Well, absolutely. Plus the 2x8 may crack on the middle under such a
load.

i

For what I expect would be better strength, rigidity and protection from
potential defects in dimensional lumber, try making a glued and screwed
box beam. Something like a top surface layer of three layers of 3/4"
plywood, two or three 2x4 members inside the box, and another layer of
3/4" ply on the bottom. You'd need two sheets of 3/4" ply, six 2x4s and
a lot of glue and screws to make two 1' wide ramps. If you want cleats
at the sides to help keep wheels from running off, apply strips of 1x2
to the top surface along the edges.

Bad ASCII art:

## ##
##################
##################
##################
## ## ##
## ## ##
## ## ##
##################

BTW, the extruded aluminum ramp ends are called "Ramparts" and sold many
places including Depot and Lowe's.

Estimating wooden ramp strength
 

On 2007-10-25, Pete C. wrote:
Ignoramus20839 wrote:

sOn 2007-10-25, dpb wrote:
Ignoramus20839 wrote:
On 2007-10-25, dpb wrote:
Ignoramus20839 wrote:
On 2007-10-25, Chris Friesen wrote:
Ignoramus20839 wrote:

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).
Using spruce pine and ignoring the 2x8, the sagulator gives a deflection
of .7" for 500lbs of load in the center of a single 8' ramp.

OK, this is great. What does your sagulator say about 1000 lbs load?
Google "sagulator" and experiment to your heart's content...


I thought that sagulator was a PC program. It is great! I have it
bookmarked and am now experimenting!!!

Looks like with 2x4x, the deflection of a 1,000 lbs load in the middle
will be about 2 inches, which is too much.

However, with 2x6s, the deflection will only be 0.36 inches, and 0.7
inches with 2,000 lbs center load.

So, it seems, that a ramp made to the shape of letter I, could easily
let me deal with 2,000 lbs wheeled loads. (such as a dolly on casters)

Well, when you're dealing with that kind of loads, don't forget the
supporting ends, joint strength and fasteners, point loading of a caster
on the 2x ramp, the downward force of the load back down the ramp
running over whatever is in the way, the load limit on a truck tailgate,
etc., etc., etc., ...


Well, absolutely. Plus the 2x8 may crack on the middle under such a
load.

i

For what I expect would be better strength, rigidity and protection from
potential defects in dimensional lumber, try making a glued and screwed
box beam. Something like a top surface layer of three layers of 3/4"
plywood, two or three 2x4 members inside the box, and another layer of
3/4" ply on the bottom. You'd need two sheets of 3/4" ply, six 2x4s and
a lot of glue and screws to make two 1' wide ramps. If you want cleats
at the sides to help keep wheels from running off, apply strips of 1x2
to the top surface along the edges.

Bad ASCII art:

## ##
##################
##################
##################
## ## ##
## ## ##
## ## ##
##################

BTW, the extruded aluminum ramp ends are called "Ramparts" and sold many
places including Depot and Lowe's.

I think that it is going to be kind of big. But I will think about
it. By the way, I heeded your advice and bought the HF load balancer a
year ago. I will check those ramparts, I am sure that I will need
them. But maybe I will make them.

i

Estimating wooden ramp strength
 

On Thu, 25 Oct 2007 12:10:00 -0500, "Pete C."
wrote:


For what I expect would be better strength, rigidity and protection from
potential defects in dimensional lumber, try making a glued and screwed
box beam. Something like a top surface layer of three layers of 3/4"
plywood, two or three 2x4 members inside the box, and another layer of
3/4" ply on the bottom.

A box beam of plywood and 2X's would make an excellent ramp, but
you've got the functions of the plywood and sawn lumber reversed. The
plywood should be the vertical webs and the 2X's the top and bottom
plates. The 2X's carry the tension and compression loads; the plywood
resists the shear between the tension and compression members.

--
Ned Simmons

Estimating wooden ramp strength
 

Ned Simmons wrote:

On Thu, 25 Oct 2007 12:10:00 -0500, "Pete C."
wrote:


For what I expect would be better strength, rigidity and protection from
potential defects in dimensional lumber, try making a glued and screwed
box beam. Something like a top surface layer of three layers of 3/4"
plywood, two or three 2x4 members inside the box, and another layer of
3/4" ply on the bottom.

A box beam of plywood and 2X's would make an excellent ramp, but
you've got the functions of the plywood and sawn lumber reversed. The
plywood should be the vertical webs and the 2X's the top and bottom
plates. The 2X's carry the tension and compression loads; the plywood
resists the shear between the tension and compression members.

The 2x's could be replaced with ply as well, however using the 2x4s just
makes construction easier. The main point is in putting engineered
lumber i.e. plywood in the positions of stress, eliminating the
potential for an undetected flaw in the dimensional lumber from causing
a catastrophic failure. Indeed, the engineered I joists for building
construction have begun to shift to engineered lumber for the top and
bottom chords of the I joists in place of the earlier dimensional
lumber.

Estimating wooden ramp strength
 

On Thu, 25 Oct 2007 11:45:15 -0400, "Lee Michaels"
wrote:


"Ignoramus20839" wrote in message
...
I have steel ramps, but they are very short and suitable for my [low]
trailer only.

I am considering making ramps from wooden boards. Specifically,
picture a ramp that looks like a letter I in cross section. The wide
part of the I is a 2x8. On the top and bottom of the I, there would be
2x4s. The "I", of course, would be laid flat for use.

Here's the ascii graphic:

. .
|==========|
~ ~

The 2x4s would be screwed to the 2x8 with wood screws, and reinforced
with glue.

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).

thanks


Two thoughts...

Why not just take the 2 X 8's and test them. Put them on a block of some
kind on the ground and roll whatever you plan to use them for onto them and
observe the deflection. This would be simple and just cost the price of a
couple boards.

I have seen a number of ramps that have a metal end on them specifically
designed for a ramp. I think that would be much more compace and work better
than your proposed 2 X 4 ends. I don't know where to purchase them, but
they are out there because I have seen them in use many times.



Even your local borg will probably have aluminum "ramp ends" for 2x8
and 2x10 lumber. They can be secured to a trailer or truck tailgate
by means of holes in the aluminum pieces and pins that go through
those holes and into matching holes you drill in the trailer or
tailgate. The 2x8 version has worked fine for me with 8 foot lumber
for lawnmowers and snow throwers (heaviest item is about 160lbs). I
never drilled holes in the tailgate of my 18 year old truck and I
don't plan to drill holes in the tailgate of the new truck either ;-)

Just FYI, the 1989 Nissan pickup was better built (both assembly and
design) than the 2008 Tacoma is. The wind noise was lower (after 18
years) than the new one and the speedometer was more accurate. The
Tacoma reads 5% high (factory spec is +/- 7%). That 5% error will
take away 5% of the warranty coverage (3000 miles of a 60000 mile
warranty). It's all drive-by-wire and the only physical correction is
a slightly larger tire size (70 series - 80 series is 5% increase).
The dealer hasn't done anything yet, except the usual "Im sorry. What
would make you happy?" and then not following up. The dealer will get
one more chance at fixing it, then I'll file a "Lemon Law" complaint
(also covers things that reduce the value of the vehicle) - which they
must respond to in writing. At least the error will be documented for
any future warranty claims...

John

Estimating wooden ramp strength
 

On Oct 25, 5:39 pm, Ignoramus20839 ignoramus20...@NOSPAM.
20839.invalid wrote:

I thought that sagulator was a PC program. It is great! I have it
bookmarked and am now experimenting!!!

Looks like with 2x4x, the deflection of a 1,000 lbs load in the middle
will be about 2 inches, which is too much.

However, with 2x6s, the deflection will only be 0.36 inches, and 0.7
inches with 2,000 lbs center load.

So, it seems, that a ramp made to the shape of letter I, could easily
let me deal with 2,000 lbs wheeled loads. (such as a dolly on casters)

i

While you are playing with the design, think about a couple of blocks
you could put between about the middle of the ramp and the ground. If
you had a block in the middle of the span, it would be like two 4 foot
ramps in series. And I think the capacity would be much higher. So
you could use you original design which would be lighter to set in
place.


Dan

Estimating wooden ramp strength
 

On 2007-10-25, wrote:
On Oct 25, 5:39 pm, Ignoramus20839 ignoramus20...@NOSPAM.
20839.invalid wrote:

I thought that sagulator was a PC program. It is great! I have it
bookmarked and am now experimenting!!!

Looks like with 2x4x, the deflection of a 1,000 lbs load in the middle
will be about 2 inches, which is too much.

However, with 2x6s, the deflection will only be 0.36 inches, and 0.7
inches with 2,000 lbs center load.

So, it seems, that a ramp made to the shape of letter I, could easily
let me deal with 2,000 lbs wheeled loads. (such as a dolly on casters)

i

While you are playing with the design, think about a couple of blocks
you could put between about the middle of the ramp and the ground. If
you had a block in the middle of the span, it would be like two 4 foot
ramps in series. And I think the capacity would be much higher. So
you could use you original design which would be lighter to set in
place.


Good point. It is not trivial, though, to add that middle support that
would be usable with different heights. But it is a very good thought,
and a solvable problem.

i

Estimating wooden ramp strength
 

John wrote:

On Thu, 25 Oct 2007 11:45:15 -0400, "Lee Michaels"
wrote:


"Ignoramus20839" wrote in message
...
I have steel ramps, but they are very short and suitable for my [low]
trailer only.

I am considering making ramps from wooden boards. Specifically,
picture a ramp that looks like a letter I in cross section. The wide
part of the I is a 2x8. On the top and bottom of the I, there would be
2x4s. The "I", of course, would be laid flat for use.

Here's the ascii graphic:

. .
|==========|
~ ~

The 2x4s would be screwed to the 2x8 with wood screws, and reinforced
with glue.

My question is, what would be the strength of this ramp if it was,
say, 8 ft long. Specifically, how much load could I place in the
middle for some reasonably low deflection (like 1-2 inches).

thanks


Two thoughts...

Why not just take the 2 X 8's and test them. Put them on a block of some
kind on the ground and roll whatever you plan to use them for onto them and
observe the deflection. This would be simple and just cost the price of a
couple boards.

I have seen a number of ramps that have a metal end on them specifically
designed for a ramp. I think that would be much more compace and work better
than your proposed 2 X 4 ends. I don't know where to purchase them, but
they are out there because I have seen them in use many times.



Even your local borg will probably have aluminum "ramp ends" for 2x8
and 2x10 lumber. They can be secured to a trailer or truck tailgate
by means of holes in the aluminum pieces and pins that go through
those holes and into matching holes you drill in the trailer or
tailgate. The 2x8 version has worked fine for me with 8 foot lumber
for lawnmowers and snow throwers (heaviest item is about 160lbs). I
never drilled holes in the tailgate of my 18 year old truck and I
don't plan to drill holes in the tailgate of the new truck either ;-)

I didn't drill holes in my tailgate either. What I do do though, is use
cargo straps wrapped around each ramp and secured to the bumper to keep
the ramps from slipping off. It wakes you up real fast when a ramp slips
out while you're backing a riding mower out of the truck...


Just FYI, the 1989 Nissan pickup was better built (both assembly and
design) than the 2008 Tacoma is. The wind noise was lower (after 18
years) than the new one and the speedometer was more accurate. The
Tacoma reads 5% high (factory spec is +/- 7%). That 5% error will
take away 5% of the warranty coverage (3000 miles of a 60000 mile
warranty). It's all drive-by-wire and the only physical correction is
a slightly larger tire size (70 series - 80 series is 5% increase).
The dealer hasn't done anything yet, except the usual "Im sorry. What
would make you happy?" and then not following up. The dealer will get
one more chance at fixing it, then I'll file a "Lemon Law" complaint
(also covers things that reduce the value of the vehicle) - which they
must respond to in writing. At least the error will be documented for
any future warranty claims...

If the dealer hasn't done anything call the regional factory rep. The
calibration is an easy adjustment with a proper scan tool and would take
a competent tech about 5 minutes if they just go by tire measurements
and 10 minutes if they measure the actual rolling radius of the tires.

Estimating wooden ramp strength
 

Ignoramus20839 wrote:

On 2007-10-25, wrote:
On Oct 25, 5:39 pm, Ignoramus20839 ignoramus20...@NOSPAM.
20839.invalid wrote:

I thought that sagulator was a PC program. It is great! I have it
bookmarked and am now experimenting!!!

Looks like with 2x4x, the deflection of a 1,000 lbs load in the middle
will be about 2 inches, which is too much.

However, with 2x6s, the deflection will only be 0.36 inches, and 0.7
inches with 2,000 lbs center load.

So, it seems, that a ramp made to the shape of letter I, could easily
let me deal with 2,000 lbs wheeled loads. (such as a dolly on casters)

i

While you are playing with the design, think about a couple of blocks
you could put between about the middle of the ramp and the ground. If
you had a block in the middle of the span, it would be like two 4 foot
ramps in series. And I think the capacity would be much higher. So
you could use you original design which would be lighter to set in
place.


Good point. It is not trivial, though, to add that middle support that
would be usable with different heights. But it is a very good thought,
and a solvable problem.

i

Actually, it is pretty trivial, just add an attachment point for basic
RV stabilizer jack stand. Something like this:
http://www.campersworld.com/product-...t_id=3332:4204

Estimating wooden ramp strength
 

On Oct 25, 7:22 pm, Ignoramus20839
Good point. It is not trivial, though, to add that middle support that
would be usable with different heights. But it is a very good thought,
and a solvable problem.

i

You don't have to have it height adjustable. Just a reasonable size
so it will fit under the ramp. If the ramp is being used for a low
thing, the support may be close to the high end, and the unsupported
length a two foot span and a six foot span. If it is being used on a
very high thing, the support may be close to the ground end, and
again you have a two foot and six foot span. But when you play with
the program you will see a six foot span is much better than an eight
foot span.

Of course cutting in to two four foot spans is even better, and those
aluminum support jacks look like a nice solution.

Dan

Estimating wooden ramp strength
 

On Oct 25, 3:10 pm, " wrote:
On Oct 25, 7:22 pm, Ignoramus20839

Good point. It is not trivial, though, to add that middle support that
would be usable with different heights. But it is a very good thought,
and a solvable problem.

i

You don't have to have it height adjustable. Just a reasonable size
so it will fit under the ramp. If the ramp is being used for a low
thing, the support may be close to the high end, and the unsupported
length a two foot span and a six foot span. If it is being used on a
very high thing, the support may be close to the ground end, and
again you have a two foot and six foot span. But when you play with
the program you will see a six foot span is much better than an eight
foot span.

Of course cutting in to two four foot spans is even better, and those
aluminum support jacks look like a nice solution.

Dan

Using deflection as a criterion for beam design is not to be condoned.

The beam MUST be designed with an allowable BENDING stress in the top
and bottom flange of the beam.

Once this stress is at an acceptable level can the design be checked
for deflection and, if too large, the beam be made stronger TO REDUCE
THE DEFLECTION.

Starting with deflection one has no idea what the bending stress is
and whether it has exceeded the allowable limit.

Since I generally do not design in wood..... if someone will supply
the info on type and grade of lumber, and allowable bending stress
(from a building code, perhaps) I would let you know the load
capacity.

Wolfgang

Estimating wooden ramp strength
 

"Lee Michaels" wrote in message
. ..


Why not just take the 2 X 8's and test them. Put them on a block of some
kind on the ground and roll whatever you plan to use them for onto them
and observe the deflection. This would be simple and just cost the price
of a couple boards.

I have seen a number of ramps that have a metal end on them specifically
designed for a ramp. I think that would be much more compace and work
better than your proposed 2 X 4 ends. I don't know where to purchase
them, but they are out there because I have seen them in use many times.




Home Depot sells the ramp ends pretty cheap. They're in the Outdoor Garden
department.

--

-Mike-

Estimating wooden ramp strength
 

"Ignoramus20839" wrote in message
...


So, it seems, that a ramp made to the shape of letter I, could easily
let me deal with 2,000 lbs wheeled loads. (such as a dolly on casters)


Why the "I" on the ramp? Especially at the ground end, it serves no purpose
that I can see and only makes it harder to get things started up the ramp.

--

-Mike-

Estimating wooden ramp strength
 

"Pete C." wrote in message
...


For what I expect would be better strength, rigidity and protection from
potential defects in dimensional lumber, try making a glued and screwed
box beam. Something like a top surface layer of three layers of 3/4"
plywood,

Holy Cow!!! Talk about over engineered! Three layers of 3/4" ply?
Expensive and heavy.

two or three 2x4 members inside the box, and another layer of
3/4" ply on the bottom. You'd need two sheets of 3/4" ply, six 2x4s and
a lot of glue and screws to make two 1' wide ramps. If you want cleats
at the sides to help keep wheels from running off, apply strips of 1x2
to the top surface along the edges.

And get a second truck to follow along and carry the ramps. But - no doubt
they will be strong.

--

-Mike-

Estimating wooden ramp strength
 

Estimating wooden ramp strength
 

Mike Marlow wrote:

"Pete C." wrote in message
...


For what I expect would be better strength, rigidity and protection from
potential defects in dimensional lumber, try making a glued and screwed
box beam. Something like a top surface layer of three layers of 3/4"
plywood,

Holy Cow!!! Talk about over engineered! Three layers of 3/4" ply?
Expensive and heavy.

$100 to build the pair of ramps. Would you want to screw around with
borderline engineered ramps when trying to move a couple thousand
pounds?


two or three 2x4 members inside the box, and another layer of
3/4" ply on the bottom. You'd need two sheets of 3/4" ply, six 2x4s and
a lot of glue and screws to make two 1' wide ramps. If you want cleats
at the sides to help keep wheels from running off, apply strips of 1x2
to the top surface along the edges.

And get a second truck to follow along and carry the ramps. But - no doubt
they will be strong.

Probably about 60# each. Not that heavy really.

Estimating wooden ramp strength
 

In article .com,
wrote:

On Oct 25, 3:10 pm, " wrote:
On Oct 25, 7:22 pm, Ignoramus20839

Good point. It is not trivial, though, to add that middle support that
would be usable with different heights. But it is a very good thought,
and a solvable problem.

i

You don't have to have it height adjustable. Just a reasonable size
so it will fit under the ramp. If the ramp is being used for a low
thing, the support may be close to the high end, and the unsupported
length a two foot span and a six foot span. If it is being used on a
very high thing, the support may be close to the ground end, and
again you have a two foot and six foot span. But when you play with
the program you will see a six foot span is much better than an eight
foot span.

Of course cutting in to two four foot spans is even better, and those
aluminum support jacks look like a nice solution.

Dan

Using deflection as a criterion for beam design is not to be condoned.

The beam MUST be designed with an allowable BENDING stress in the top
and bottom flange of the beam.

Once this stress is at an acceptable level can the design be checked
for deflection and, if too large, the beam be made stronger TO REDUCE
THE DEFLECTION.

Starting with deflection one has no idea what the bending stress is
and whether it has exceeded the allowable limit.

Since I generally do not design in wood..... if someone will supply
the info on type and grade of lumber, and allowable bending stress
(from a building code, perhaps) I would let you know the load
capacity.

I think that Machinery's Handbook has strength and modulus data on wood.

One thing to consider is tipping due to an offcenter load, if the road
surface is too soft and the ramp too narrow.

Joe Gwinn

Estimating wooden ramp strength
 

Joseph Gwinn wrote:
In article .com,
wrote:

On Oct 25, 3:10 pm, " wrote:
On Oct 25, 7:22 pm, Ignoramus20839

Good point. It is not trivial, though, to add that middle support
that would be usable with different heights. But it is a very
good
thought, and a solvable problem.

i

You don't have to have it height adjustable. Just a reasonable
size
so it will fit under the ramp. If the ramp is being used for a
low
thing, the support may be close to the high end, and the
unsupported
length a two foot span and a six foot span. If it is being used
on
a very high thing, the support may be close to the ground end,
and
again you have a two foot and six foot span. But when you play
with
the program you will see a six foot span is much better than an
eight foot span.

Of course cutting in to two four foot spans is even better, and
those aluminum support jacks look like a nice solution.

Dan

Using deflection as a criterion for beam design is not to be
condoned.

The beam MUST be designed with an allowable BENDING stress in the
top
and bottom flange of the beam.

Once this stress is at an acceptable level can the design be
checked
for deflection and, if too large, the beam be made stronger TO
REDUCE
THE DEFLECTION.

Starting with deflection one has no idea what the bending stress is
and whether it has exceeded the allowable limit.

Since I generally do not design in wood..... if someone will supply
the info on type and grade of lumber, and allowable bending stress
(from a building code, perhaps) I would let you know the load
capacity.

I think that Machinery's Handbook has strength and modulus data on
wood.

http://www.fpl.fs.fed.us/documnts/fp.../fplgtr113.htm

One thing to consider is tipping due to an offcenter load, if the
road
surface is too soft and the ramp too narrow.

Joe Gwinn

--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

Estimating wooden ramp strength
 

On Thu, 25 Oct 2007 12:50:46 -0500, "Pete C."
wrote:

Ned Simmons wrote:

On Thu, 25 Oct 2007 12:10:00 -0500, "Pete C."
wrote:


For what I expect would be better strength, rigidity and protection from
potential defects in dimensional lumber, try making a glued and screwed
box beam. Something like a top surface layer of three layers of 3/4"
plywood, two or three 2x4 members inside the box, and another layer of
3/4" ply on the bottom.

A box beam of plywood and 2X's would make an excellent ramp, but
you've got the functions of the plywood and sawn lumber reversed. The
plywood should be the vertical webs and the 2X's the top and bottom
plates. The 2X's carry the tension and compression loads; the plywood
resists the shear between the tension and compression members.

The 2x's could be replaced with ply as well, however using the 2x4s just
makes construction easier.

No question about that.

The main point is in putting engineered
lumber i.e. plywood in the positions of stress, eliminating the
potential for an undetected flaw in the dimensional lumber from causing
a catastrophic failure.

But there is stress in both the webs and flanges. With a little care
in selecting the 2Xs you're unlikely to have a problem using them in
tension or compression for the bottom and top plates. Any hidden
defects, or overloading, are much more likely to cause a failure along
the grain if they're subject to shear. The criss-cross grain of the
plywood makes it the better choice for carrying the shear in the webs.

--
Ned Simmons

Estimating wooden ramp strength
 

Looks like with 2x4x, the deflection of a 1,000 lbs load in the middle
will be about 2 inches, which is too much.

However, with 2x6s, the deflection will only be 0.36 inches, and 0.7
inches with 2,000 lbs center load.

So, it seems, that a ramp made to the shape of letter I, could easily
let me deal with 2,000 lbs wheeled loads. (such as a dolly on casters)

i

Why not nix the idea of the 2X4's on the sides and do this instead. Make
your own metal ramp ends that you fit to the ends of the ramps and then rout
slots on the underside of the boards where you run a couple of 1/4 or 3/8
rods that are fastened to the metal ends. This way the lumber will be in
compression, and the steel will restrain the wood from flexing too much.

I did something similar to some saggy rafters and was able to jack the whole
roof straight.

--

__
Roger Shoaf

Important factors in selecting a mate:
1] Depth of gene pool
2] Position on the food chain.

Estimating wooden ramp strength
 

On Oct 25, 2:22 pm, Ignoramus20839 ignoramus20...@NOSPAM.
20839.invalid wrote:
....
Good point. It is not trivial, though, to add that middle support that
would be usable with different heights. But it is a very good thought,
and a solvable problem.

Car jack stands work well for this as long as you tie the ramps to the
vehicle and use a crosswise plank between the stands and the ramps.
The ramps may twist if supported only by the narrow stand tops, and
when the vehicle sinks from the load, the ramp ends lift off the
ground and slide. Put some tiedown eyes on the sides of the ramp.

Jim W

Estimating wooden ramp strength
 

Mike Marlow wrote:

Home Depot sells the ramp ends pretty cheap. They're in the Outdoor Garden
department.


I have a set of those. They work fine with 2x8's getting my 500 pound
wide cut mower in and out of my 4x4 Tacoma twice a year.

Estimating wooden ramp strength
 

"Pete C." wrote in message
...
Mike Marlow wrote:

"Pete C." wrote in message
...


For what I expect would be better strength, rigidity and protection
from
potential defects in dimensional lumber, try making a glued and screwed
box beam. Something like a top surface layer of three layers of 3/4"
plywood,

Holy Cow!!! Talk about over engineered! Three layers of 3/4" ply?
Expensive and heavy.

$100 to build the pair of ramps. Would you want to screw around with
borderline engineered ramps when trying to move a couple thousand
pounds?

How did this get to be a couple thousand pound project? Wasn't the OP
talking about such things as mowers and snowblowers? Who's going to be
building ramps to load a couple thousand pound object into the back of a
pickup?



two or three 2x4 members inside the box, and another layer of
3/4" ply on the bottom. You'd need two sheets of 3/4" ply, six 2x4s and
a lot of glue and screws to make two 1' wide ramps. If you want cleats
at the sides to help keep wheels from running off, apply strips of 1x2
to the top surface along the edges.

And get a second truck to follow along and carry the ramps. But - no
doubt
they will be strong.

Probably about 60# each. Not that heavy really.

Very heavy compared to the alternatives.

--

-Mike-

Estimating wooden ramp strength
 

Mike Marlow wrote:

Who's going to be
building ramps to load a couple thousand pound object into the back of a
pickup?

I'd like to see the pickup with a couple thousand pounds in the back.

May the OP should just give up and hire a roll-back. G

Estimating wooden ramp strength
 

On 2007-10-26, B A R R Y wrote:
Mike Marlow wrote:

Who's going to be
building ramps to load a couple thousand pound object into the back of a
pickup?

I'd like to see the pickup with a couple thousand pounds in the back.

May the OP should just give up and hire a roll-back. G


I have a trailer that can carry a lot more than 2,000 lbs. I made it
myself, kind of.

http://igor.chudov.com/projects/Home...th-M105A2-Bed/

It can carry about 4k lbs.

i

Estimating wooden ramp strength
 

"Ignoramus7291" wrote

I have a trailer that can carry a lot more than 2,000 lbs. I made it
myself, kind of.

http://igor.chudov.com/projects/Home...th-M105A2-Bed/

It can carry about 4k lbs.


After viewing your very impressive trailer build, I have two very irreverant
thoughts.

The first is a mental picture of those crummy trailer kits sold at the borg
and Harbor Freight. You know, the light weight trailers that come in two
big cardboard boxes. Lots of pieces that you bolt together.

What you built is twenty times heavier, a hundred times more sturdy and
million times more classy that those cheap kits.

The second thought is that cammo paint job looks really good on the trailer.
When are you going to paint the truck to match the trailer?

Estimating wooden ramp strength
 

Why not nix the idea of the 2X4's on the sides and do this instead. Make
your own metal ramp ends that you fit to the ends of the ramps and then rout
slots on the underside of the boards where you run a couple of 1/4 or 3/8
rods that are fastened to the metal ends. This way the lumber will be in
compression, and the steel will restrain the wood from flexing too much.

I like this idea, though the earlier idea of bolting on angle is
probably easier.

Alternatively, consider changing from box store softwood to a locally
milled rough hardwood like oak or ash. The wood itself is stiffer and
you'll gain a little more stiffness from it being thicker (close to a
full 2").

--Glenn Lyford

Estimating wooden ramp strength
 

On 2007-10-26, Lee Michaels wrote:

"Ignoramus7291" wrote

I have a trailer that can carry a lot more than 2,000 lbs. I made it
myself, kind of.

http://igor.chudov.com/projects/Home...th-M105A2-Bed/

It can carry about 4k lbs.


After viewing your very impressive trailer build, I have two very irreverant
thoughts.

The first is a mental picture of those crummy trailer kits sold at
the borg and Harbor Freight.

I bought one once. Sold it to my friend promptly. Could not stand the
sight of it.

What you built is twenty times heavier, a hundred times more sturdy and
million times more classy that those cheap kits.

It is more like 10 times heavier. But yes. This is "the real thing".

The second thought is that cammo paint job looks really good on the trailer.
When are you going to paint the truck to match the trailer?

I love the camo job, yes, and here's my dilemma. I feel like I need to
sand and paint over some spots, but I do not know how to prevent the
pattern.

This trailer actually gets compliments from completely random people
on the streets.

Did you see the pictures of bullet holes on this trailer? (real bullet
holes, not fake stickers)

Making it was fun. It was my winter project. It actually took
relatively little time due to me wanting to get it out of the garage
so as to not tp upset my wife too much. But it was as lot of work.

i

Estimating wooden ramp strength
 

On 2007-10-26, Ignoramus7291 wrote:
I love the camo job, yes, and here's my dilemma. I feel like I need to
sand and paint over some spots, but I do not know how to prevent the
pattern.

I mean, how to keep the pattern, I do not know what I was thinking.

i

Estimating wooden ramp strength
 

"Ignoramus7291" wrote in message
...
On 2007-10-26, Ignoramus7291 wrote:
I love the camo job, yes, and here's my dilemma. I feel like I need to
sand and paint over some spots, but I do not know how to prevent the
pattern.

I mean, how to keep the pattern, I do not know what I was thinking.


That information has to be around someplace. i have seen good cammo paint
jobs done with spray paint (in a can).