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Had to break out the calculator

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Topic Originally create back in November of 2004:


We were called out to this today. I had to break out the calculator to figure this one.

Total Weight 360,000 lbs
19 axles
Hard surface
10% grade
The Driver blew his drive-train 2 times trying to make this grade. All in all we made it. What do you come up with.



Kevin aka Polock said:

Hey Jon how warm was that day??? Did the unit sink into the pavement?? Bubba wanted to know that question.

The Bubba and Polock Show answer issssss

Resistance Is 22,500 lbs.

Now my question is are u going to tow this uhit or winch it??
If you are going to tow it ... poor tow truck

Swingin' by the Hook


Towstany said:

50 degrees. All axles on good pavement.



Kevin aka Polock said:

Bubba says OK,


Well I guess (like the answer) me and bubba are the only two to put our heads on the chopping block...

Swingin' by the Hook


DW Carter said:

77760 Don't ask how I came up with that. lol

360,000 lbs 10 percent grade 360,000x.166= 59760
surface 360,000x5%=18,000
total 77,760 lbs

DW Carter WM92343


1Towman said:

surface resistance estimate 5% of vehical weight #18000
Gradiant Resistance estimate 20% #72000 I would guess
it would take #90000 minimum pull to get that moving
Unknown Member said:
I'm taking it that all wheels roll free
78,120 lbs. of resistance to overcome.

360,000 lbs. rolling resistance hard surface all axles - ( one vehicle ) 5% ( 360,000 X .05 = 18,000 lbs. surface resistance)

360,000 lbs. 10 Degree Grade ( 16.7 % ) ( all vehicles in same environment no weight transfer required )
(360,000 X .167 = 60,120 )

18,000 lbs. surface resistance
+ 60,120 lbs. gradient resistance
78,120 lbs. total resistance to overcome
Unknown Member said:
Am I right in saying there's 74 tires on that rig? HOLY CRAP

360,000 Static weight x 5% (rolling resistance) = 18000 lbs.

360,000 Static Weight x 25% (gradient figured at 15%) = 90,000 lbs.

I would rig for a pull of 108,000 lbs.

Now, if I wanted to be really exact, I could say 10% = 16.7% of the static weight to overcome. Using that figure,

360,000 x 16.7% = 60,120 lbs, adding in the rolling resistance of 18,000 lbs, you would have a total resistance of

78,120 lbs.

I think, in this situation, with the top of the hill getting steeper as I go, I would go ahead and play it safe and rig for 108,000 lbs of resistance.
Did ya see? we ALL came up with the same answers. I think that's just cool as hell. A perfect example of teamwork. Obviously, having a WreckMaster on this scene would ASSURE success and would certainly impress those that watched.

But what do I know, ....... I'm a light duty tower. I also don't think I would attempt to lift it. Why should I subject my rig to that kind of tortue (I don't know the capabilities of the tow truck and the grade has already damaged one drivetrain...... )
Towtrk1 said:
...still looking for calculator...
DrHook541 said:
Found my calculator ... Towing resistance calculator ... and you got it right. This also shows the anchorability required would be 117180 lbs. As we were not given a breakdown in axle weights (treating the whole unit as one vehicle), we cannot factor in the gradient weight transfer, which might result in a different set of numbers. But we are close enough to know what we will need to get the job done.
C'ya in the ditch.
Unknown Member said:
Doc, the weight transfer calculations aren't needed here. All the axles are in the same "environment" It would be a different story if the rear set of axles were off the side of the road and in a different environment (mired tire depth or wheel depth)
Kevin aka Polock said:
I met a fellow one time who told me to keep putting blocks in the line until it moved,...........

5% hard surface 18,000 lbs.
Plus the 16.7% of the GVW for the 10% uphill grade 59967 lbs.

I'm rigging for 77,976 lbs.
But if I'm winching the whole unit. I would rig for the WLL of my lines. Also figuring the number of lines, snatch blocks and what I'm anchoring to. I would consider that also.

So now I would rig for 90000 lbs. The Polish fudge factor, a safety factor and the oh sh*t factor. I would rather pull more and be safe then not enough.Swingin' by the Hook
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You just don't see these kind of discussions on social media anymore...

Jon Standiford 

Aka Towstany

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