Pulling Force

The usual word of caution ... my buddy thought he'd be a smart ass and took
his cat into the soggy field to pull out the tractor ... you guessed it ...
it sank.


"g3_josh" > wrote in message
om...
> I've got a simple problem for y'all but it its going to have a
> complicated answer. Let me set up a senario: You've got a
> rope,cable,chain, or other pulling device that (ignoring shock
> loading) has a break strength of 40,000 lbs. How large of a vehicle
> can I "get unstuck"? Specifically though I'd like to know how much
> force to pull a fully loaded tractor-trailer (semi) full of beets out
> of mud (up to its axle).
>
> I realize that this depends on the how the vehicle is stuck, what it
> is stuck in, how deep, whether or not the vehicles wheels are able to
> role, etc...
> A better question might be:
>
> How much pulling force, without "jerking" or "getting a run at it",
> can a vehicle produce under ideal circumstances.
> 4X4 Pickup Truck?
> Semi?
> 2WD Tractor?
> 4WD Tractor?
> Dozer?
>
> Tractor manufacturers sometimes give a PTO HP or even a draw-bar HP
> but I can't get a draw-bar pulling force from HP (without a few more
> details). Taking engine torque and multiplying it by the drive ratio
> seems like perhaps the only way to get somewhat close (although
> perhaps a bit exaggerated).
>
>
> Josh

With our Jeeps and 4x4's we generally figure we can pull something that
is half the rated pull of the winch out of the mud.

So for my 9,000 lb winch, I can drag a 4500 lb vehicle out of the mud
'if' my vehicle is anchored because my CJ7 only weighs in at 3000 lb or
so and I can drag my mud tires.

I also can use a pulley block to up my winch's pull to 18,000 lb.

HP of the engine or winch motor doesn't really come into it. The
winches are rated in lb they can pull.

If you are taking just a straight strap pull, then the best traction and
biggest engine wins hands down.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

g3_josh wrote:
>
> I've got a simple problem for y'all but it its going to have a
> complicated answer. Let me set up a senario: You've got a
> rope,cable,chain, or other pulling device that (ignoring shock
> loading) has a break strength of 40,000 lbs. How large of a vehicle
> can I "get unstuck"? Specifically though I'd like to know how much
> force to pull a fully loaded tractor-trailer (semi) full of beets out
> of mud (up to its axle).
>
> I realize that this depends on the how the vehicle is stuck, what it
> is stuck in, how deep, whether or not the vehicles wheels are able to
> role, etc...
> A better question might be:
>
> How much pulling force, without "jerking" or "getting a run at it",
> can a vehicle produce under ideal circumstances.
> 4X4 Pickup Truck?
> Semi?
> 2WD Tractor?
> 4WD Tractor?
> Dozer?
>
> Tractor manufacturers sometimes give a PTO HP or even a draw-bar HP
> but I can't get a draw-bar pulling force from HP (without a few more
> details). Taking engine torque and multiplying it by the drive ratio
> seems like perhaps the only way to get somewhat close (although
> perhaps a bit exaggerated).
>
> Josh

With our Jeeps and 4x4's we generally figure we can pull something that
is half the rated pull of the winch out of the mud.

So for my 9,000 lb winch, I can drag a 4500 lb vehicle out of the mud
'if' my vehicle is anchored because my CJ7 only weighs in at 3000 lb or
so and I can drag my mud tires.

I also can use a pulley block to up my winch's pull to 18,000 lb.

HP of the engine or winch motor doesn't really come into it. The
winches are rated in lb they can pull.

If you are taking just a straight strap pull, then the best traction and
biggest engine wins hands down.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

g3_josh wrote:
>
> I've got a simple problem for y'all but it its going to have a
> complicated answer. Let me set up a senario: You've got a
> rope,cable,chain, or other pulling device that (ignoring shock
> loading) has a break strength of 40,000 lbs. How large of a vehicle
> can I "get unstuck"? Specifically though I'd like to know how much
> force to pull a fully loaded tractor-trailer (semi) full of beets out
> of mud (up to its axle).
>
> I realize that this depends on the how the vehicle is stuck, what it
> is stuck in, how deep, whether or not the vehicles wheels are able to
> role, etc...
> A better question might be:
>
> How much pulling force, without "jerking" or "getting a run at it",
> can a vehicle produce under ideal circumstances.
> 4X4 Pickup Truck?
> Semi?
> 2WD Tractor?
> 4WD Tractor?
> Dozer?
>
> Tractor manufacturers sometimes give a PTO HP or even a draw-bar HP
> but I can't get a draw-bar pulling force from HP (without a few more
> details). Taking engine torque and multiplying it by the drive ratio
> seems like perhaps the only way to get somewhat close (although
> perhaps a bit exaggerated).
>
> Josh

Personally I've seen a grain wagon (unloaded) stuck so deep in mud
that it took 2 large 4wd tractors, a Cat 6 wheel road grader, and a
Cat Dozer (not to mention 300 ft of cable) to pull it out (5ft
floatation tires and all).

Anyway, yes I realize there are many complicating variables but...

I guess I need to be a little more specific - I've been doing an
independent engineering analysis of a device called the Safe-T-Pull
for a company here in North Dakota. The device is essentially a 10
foot 6"X6" section of square tubing with a tounge hitch at one end and
a large pin at the other. The Safe-T-Pull is sold with a large half
ring hitch that is attached to the frame of your truck(custom designed
for many different makes and models). Without going into too much
detail, the Safe-T-Hitch is attached to the drawbar of a tractor, when
a truck gets stuck the tractor is backed up to the front of the truck,
the Safe-T-Pull is set in place via hydraulic cylinders from inside
the tractor. The idea here is: the operator doesn't need to leave the
cab of the tractor to crawl through knee high mud to hook up a chain,
in fact many farmers just leave the Safe-T-Pull attached to the
tractor throughout harvest. Secondly the Safe-T-Pull is much safer
than cable or chain because it won't break in a violent manner (it
doesn't store energy). Moving along, following my engineering
analysis I found that most of the Safe-T-Pull can pull up to
100,000lbs without yielding, however a chain is only as strong as it's
weakest link, the weakest link can handle perhaps 58,000 lbs pull.
Somebody is going to ask me what kind of GVW (gross vehicle weight)
can this device pull? And under what conditions?
Any suggestions?

Personally I've seen a grain wagon (unloaded) stuck so deep in mud
that it took 2 large 4wd tractors, a Cat 6 wheel road grader, and a
Cat Dozer (not to mention 300 ft of cable) to pull it out (5ft
floatation tires and all).

Anyway, yes I realize there are many complicating variables but...

I guess I need to be a little more specific - I've been doing an
independent engineering analysis of a device called the Safe-T-Pull
for a company here in North Dakota. The device is essentially a 10
foot 6"X6" section of square tubing with a tounge hitch at one end and
a large pin at the other. The Safe-T-Pull is sold with a large half
ring hitch that is attached to the frame of your truck(custom designed
for many different makes and models). Without going into too much
detail, the Safe-T-Hitch is attached to the drawbar of a tractor, when
a truck gets stuck the tractor is backed up to the front of the truck,
the Safe-T-Pull is set in place via hydraulic cylinders from inside
the tractor. The idea here is: the operator doesn't need to leave the
cab of the tractor to crawl through knee high mud to hook up a chain,
in fact many farmers just leave the Safe-T-Pull attached to the
tractor throughout harvest. Secondly the Safe-T-Pull is much safer
than cable or chain because it won't break in a violent manner (it
doesn't store energy). Moving along, following my engineering
analysis I found that most of the Safe-T-Pull can pull up to
100,000lbs without yielding, however a chain is only as strong as it's
weakest link, the weakest link can handle perhaps 58,000 lbs pull.
Somebody is going to ask me what kind of GVW (gross vehicle weight)
can this device pull? And under what conditions?
Any suggestions?

> >
> > Josh
>
> Rules of thumb: PTO horsepower is about 86% of engine horsepower.
> Drawbar horsepower is about 86% of PTO horsepower. I think this is for 2WD
> tractors in average conditions.
> One horsepower = 33,000 Ft.Lb./min
>
> There isn't a good answer to your question without more information. How
> big are the tractors? 100 HP?
> This won't help you much since traction difference will probably be a big
> factor. The tractors should easily out pull the pickup and probably the
> semi in dirt or mud. The dozer should out pull everything on dirt. My
> guess is the dozer wouldn't do too well on concrete.
> Wheel slippage for tractors is usually in the 10% -15% range in good
> conditions. That's considered the most efficient for field work.
> You might be able to get some information on drawbar pull from the
> University of Nebraska Tractor Test Lab. I don't know if they have a
> website.
>
> Dean
>
That was great help Dean. UNTTL has a site it's, http://tractortestlab.unl.edu

Josh

> >
> > Josh
>
> Rules of thumb: PTO horsepower is about 86% of engine horsepower.
> Drawbar horsepower is about 86% of PTO horsepower. I think this is for 2WD
> tractors in average conditions.
> One horsepower = 33,000 Ft.Lb./min
>
> There isn't a good answer to your question without more information. How
> big are the tractors? 100 HP?
> This won't help you much since traction difference will probably be a big
> factor. The tractors should easily out pull the pickup and probably the
> semi in dirt or mud. The dozer should out pull everything on dirt. My
> guess is the dozer wouldn't do too well on concrete.
> Wheel slippage for tractors is usually in the 10% -15% range in good
> conditions. That's considered the most efficient for field work.
> You might be able to get some information on drawbar pull from the
> University of Nebraska Tractor Test Lab. I don't know if they have a
> website.
>
> Dean
>
That was great help Dean. UNTTL has a site it's, http://tractortestlab.unl.edu

Josh

Chris Phillipo wrote:
> My 6000lb. warn winch on a single line pull can just bearly budge my
> 4000lb 4 runner up a slight grade buried to the frame in bog, assisting
> it by slowly driving the wheels and it can do it no problem. Sounds
> like the device he's talking about is more likely to break frames and
> hitches than to break itself.

I had a similar experience buried to the axles in deep, snow. 9000# winch, 4500 lb. 4Runner, straight pull did nothing except stall the winch motor, put the truck in gear and let the wheels turn and it popped out of the hole with ease.

--
Roger

Chris Phillipo wrote:
> My 6000lb. warn winch on a single line pull can just bearly budge my
> 4000lb 4 runner up a slight grade buried to the frame in bog, assisting
> it by slowly driving the wheels and it can do it no problem. Sounds
> like the device he's talking about is more likely to break frames and
> hitches than to break itself.

I had a similar experience buried to the axles in deep, snow. 9000# winch, 4500 lb. 4Runner, straight pull did nothing except stall the winch motor, put the truck in gear and let the wheels turn and it popped out of the hole with ease.

--
Roger