Draw bar pull of a truck.

[never_retreat]

Here is my story.
Almost home and a tree in the road. someone was nice enough to put up cones instead of moving the tree. Turn truck around attach strap to tree and truck. Rip tree the rest of the way out of the ground, drag to shoulder. See its not that hard. At least two people from the 10 other cars helped drag the twigs out of the way.

Here is the problem. I tore up my 20' tow strap. Actually the end i put over the hitch ball. It was a two inch wide single ply, 3200 lb strength.
Obviously I need to buy a new one. Stronger of course.

Anyone know what the max pull of my truck is or how to figure it out.
Its a 02 F250 super duty with an auto trans and 7.3L engine. In 4 low of course.
I know there are math nerds here.

[41magsnub]

Not to dodge the math, but I have chains for that rather than a tow strap.

[41magsnub]

Here's some specs that might help things along for those that know the math:

http://www.fordf150.net/specs/02fsuperover.htm

The 7.3L Power StrokeTM turbo diesel V-8, the best-selling engine in its class - gas or diesel, produces 250 horsepower and 505 lb.-ft. of torque with the automatic transmission

[41magsnub]

According to:  https://www.fleet.ford.com/showroom/rv_trailer_towing/2002/2002_pickups.pdf

12,500 lbs

[never_retreat]

Not to dodge the math, but I have chains for that rather than a tow strap.

Ya I know but I rather have a couple of light straps in the back than 100 lbs of chain. I have one good long 5/16 type 7 chain. I might have to put it back in the truck.

[never_retreat]

According to:  https://www.fleet.ford.com/showroom/rv_trailer_towing/2002/2002_pickups.pdf

12,500 lbs

Thats recommend max trailer weight. I'm referring to brute force.

[230RN]

"505 lb.-ft. of torque"

Calculate pull from this and the tire size?

A one-foot radius wheel should give you 505 lbs of pull... larger wheels, less.

Doesn't sound right, though.  So what's wrong?  Seems that torque should be transmittable almost 100% through to the wheel.


Hmmmm....

[Jamisjockey]

I am dodging the math. It's not necessary.

The old 4x4 geek in me says, at least 30' of 20,000lb rated strap.

here's a 3x30x30,000
http://www.amazon.com/Smittybilt-CC330-30-Recovery-Strap/dp/B001CF4UXU/ref=sr_1_1?ie=UTF8&qid=1307672569&sr=8-1

I'm not a huge fan of chains.  They are heavy and bulky, especially if you need more than a few feet.  They don't store as easily as a strap.  And when they break, they become missles.

Make sure and buy a couple clevis's to go with it. Have a couple extras for creative situations, as well as a short length of choker chain.

http://www.tractorsupply.com/hitch-pins/straight-clevis-pin-amp-clip-heavy-duty-0268860

4x4 geek tip:

Roll your strap for storage.  You can use a piece of duct tape to keep it rolled up, or get real fancy by cutting a piece of car sized innertube into a 3" wide rubber band to use.  Also, to protect the strap when you're wrapping it around stuff like trees, use a length of motorcycle innertube

http://www.amazon.com/b?ie=UTF8&node=404809011

Buy a cheap one and cut it into several lengths including one 2' section.  Slide it over the strap and use it as a buffer anywhere there might be chafing during a pull.  Another method is to duct tape a towel, jacket or floor mat over whatever might cause chafing (like an angled tow around a large tree).


Do not put the strap over your ball. Instead, run it through the spot on your hitch where you should put your safety chains, double it back, secure it with a clevis.  Or buy one of these
http://www.polyperformance.com/shop/Warn-Receiver-Shackle-Bracket-p-19320.html?utm_source=google&utm_medium=base&utm_campaign=4X4products
There are some clevis' out there that are wide enough for you to just put them on the hitch, and use the clevis pin to run through the hitch pin holes.  Takes some hunting, though.

[never_retreat]

Actually my truck is making about 300hp.   Just a little mod.
Flying chain is one reason I don't like chain. I usually only use it to drag things where I know I would damage a strap and for binding stuff down.
I used to have one of these. But someone else needed it more than me.

I usually have plenty of shackles in the truck, but the extra stuff usually comes out in the non winter months.
With the amount of trees blocking roads around here lately i might just start keeping the chain saw in the tool box.

[41magsnub]

My 30' of 3/8" chain plus 2 3' chokers fits nicely in a small canvas tool bag behind the seat of my truck.  It sort of flattens out and does not take up hardly any room.

[CNYCacher]

"505 lb.-ft. of torque"

Calculate pull from this and the tire size?

A one-foot radius wheel should give you 505 lbs of pull... larger wheels, less.

Doesn't sound right, though.  So what's wrong?  Seems that torque should be transmittable almost 100% through to the wheel.


Hmmmm....

Gearing increases and decreases torque, which is why it's kind of a useless figure to be throwing around.  Horsepower is all that matters.  It's a measure of power because it is torque times rotational speed.

[Tallpine]

Here is the problem. I tore up my 20' tow strap. Actually the end i put over the hitch ball. It was a two inch wide single ply, 3200 lb strength.

Tie a bowline in the end to put over the hitch ball the next time 

[zxcvbob]

I keep a 20' piece of 5/16" grade 70 chain in a little box behind the seat of my truck.  I used to carry a 100' roll of wire rope (I don't know what size, I think 5/16" or 11/32") and a short 3/8" logging chain until I loaned them out last year and haven't got 'em back yet -- but I know where they are.

[Jim147]

We bent two frames seeing how much we could pull. The problem was we had no way of measuring what we were pulling before the frame bent.

One was a 70' split level mobile home that buried the jack into the road due to a sharp rise. The straight six in granny had no problem pulling it even when it dug in.

The other was a load of steel. Lots and lots of steel.


jim

[kgbsquirrel]

Not to dodge the math, but I have chains for that rather than a tow strap.

Ditto. A pair of 30' long 4,500lb rated chains stowed in the truck. Each chain weighs about 15-20 lbs. Though now I think I'll also add one of those straps for good measure.

@Jamis: If you can get your mitts on old fire hose I've found that to be the absolute best chaffing gear the in the world. When a hose wore out and was no longer good for it's original purpose on the ship we would cut it into lengths and use it on mooring lines and other places. Heavy vulcanized rubber on the inside, heavy canvas on the outside. Perhaps check the local fire departments and see if they are tossing out old hoses?

[geronimotwo]

in general pull is a direct relation to vehicle weight.  6000lb vehicle = 6000lb drawbar pull.  obviously traction is also important.

[230RN]

CNYCacher:

Gearing increases and decreases torque, which is why it's kind of a useless figure to be throwing around.  Horsepower is all that matters.  It's a measure of power because itis torque times rotational speed.

Yeah, thanks.  I knew I was having some kind of brain fart there. It was a long day.

Terry, 230RN

[drewtam]

You need the complete engine torque curve, each trans gear ratio, diff ratio, tire size, and trans efficiency to create the drawbar pull curve. Or just use the quoted peak torque to evaluate the one point.

Engine torque x trans ratio x diff ratio x tire size x powertrain eff = tractive fore

It is intuitive that 1st gear will have the most drawbar, since it has the most gear ratio, while all other performance items remain the same.
The tractive force can mathematically exceed the grip  of the tire; in such a case the tires will spin. Tire grip is a major limiting factor for low gear pull force.

[Hawkmoon]

You don't need the math. That engine will put out enough "brute force" to rip up the frame and tow hitch, so save your slide rule.

You had a 2" strap that was rated at only 3200 pounds? My 2" strap is rated at 20,000 pounds, and the 3" x 30' straps I see in the 4x4 catalogs are typically rated 30,000 pounds. You're shopping in the wrong stores.

[charby]

I keep a 10' tow strap in my truck, if I can't use that I call a tow truck. I also carry a high lift jack that I can use as wench if I am traveling off the beaten path.

I've damaged a few vehicles trying to pull people out so I don't do it anymore and I try to keep out of areas where I may get horribly stuck.

[Tallpine]

The only time that I've had a strap break was from chafing right beside the hook where it had rubbed on the bottom edge of a bumper (back when they made bumpers).

Better to have the strap or chain break than break something else.

Wire rope is stronger than chain, but it will also whip nastily if it breaks 

[Chuck Dye]

...a high lift jack that I can use as wench...

That one is really tempting.  Could you please edit it before I succumb to the temptation?

[Jamisjockey]

Ditto. A pair of 30' long 4,500lb rated chains stowed in the truck. Each chain weighs about 15-20 lbs. Though now I think I'll also add one of those straps for good measure.

@Jamis: If you can get your mitts on old fire hose I've found that to be the absolute best chaffing gear the in the world. When a hose wore out and was no longer good for it's original purpose on the ship we would cut it into lengths and use it on mooring lines and other places. Heavy vulcanized rubber on the inside, heavy canvas on the outside. Perhaps check the local fire departments and see if they are tossing out old hoses?

Agreed.  I've seen it done before, it works better than the innertube trick. Cut into 2' long pieces and store with your recovery gear.  When needed, slide over tow strap or winch cable.  Works as a great tree-saver, too, for winching operations.

[charby]

That one is really tempting.  Could you please edit it before I succumb to the temptation?

Temptation of buying one or making some Tony Weiner reference?

I know wench is not winch, but when I used it, it was a wench, because I'm pissed and I called my old truck a son of a bitch because I got struck quite frequently with it. Open rearends suck on a 4x4.

[41magsnub]

Open rearends suck.

snicker...