M109 maximum angle?

[Spook556]

Tried looking this up in the manuals, no luck. Does anybody know what the maximum recommended angle for a standard M109A3 would be?

As in, side-to-side lean. I have a clinometer I will be mounting on the dash, and it got me to thinking... how far off the vertical can you drive (assuming hard pavement) before you are approaching the "danger zone"? I don't want to do the physics test with my truck; I assume there is a good rule of thumb out there.


Thanks!


Spook

 

[Jakob]

I know in a cargo truck, even a few degrees feels like twenty.

 

[panshark]

You'll have to ask gimpy what his clinometer was reading when his horizon shifted.

 

[motomacguyver]

It depends on the Center Of Gravity of the truck, fuel, people and cargo load. (Anything above the axels, divided by the wheel width? -- I don’t know the formula, someone WAY smarter then me will have to help here)

I'm thinking an equilateral triangle, with the load at the top point, and the side load lines, running through the hubs. If your load is short and heavy, (2" thick 7’x11’ steel plate) it should help you. If it’s tall, not so much.

It's probably a lot further than it would seem, especially when empty. But....I wouldn't want to try it in the real world with MY equipment!

Sorry it's not a definitive answer.

Good question, subscribed.

 

[Bighurt]

Rollover formula

LA=V2/Rg (Lateral Acceleration = velocity squared divided by the radius of the corner multiplied by gravity). LA represents lateral acceleration which is expressed in terms of G-forces. It's a factor that's measured by calculating speed and the radius of any given turn (R).

 

[Ferroequinologist]

I know I've had mine at some crazy angles.

My old destroyer, the superstructure was designed to shear off at 45 degrees. Us engineers knew we could run the ship, and there were days we tried to get to 45 degrees... I have the clinometer that was mounted in Central Control, and it has a tick mark on it where we hit 43 degrees once...

 

[Spook556]

Well, thank you all... this is all very interesting stuff!

But I still don't have a number! Am I really going to have to install the clinometer and jack up one side until it falls over?

Okay, I am not that crazy. But it seems like somebody out there ought to be able to find it.


Thanks!


Spook.

 

[LowTech]

I've seen Elise's "She Beast" like this many, many times on our Dirt Track Trip


One time climbing down into a major wash, I saw it (in my mirror) leaning so far that all I could think was . . . DON'T STOP! . . . DON'T STOP!! . . . DON'T STOP!!!


Her rig is currently singled w/ stock 900x20', and WAY TOO narrow a track.
We have some mod 'd hemmts, but are still saving for tires.

 

[zout]

Spook556 - whatever you do - be sure to post pictures or a video would be acceptable of the jacking till falling over occurs.

Then when you think you have seen the last of your truck on its side - we will bring it back up to remind you.

 

[Bad_Carp]

While I don't know the exact angle, I do know that the one identifier to a roll over is you will soil your underwear just before it goes past the point of no return.

And if you listened to your mom, you'll have a clean pair in the glove box.

 

[zout]

BigHurt did post some interesting calculations to figure it out - but it gave me a headache after reading the second part of the formula - its just that I do not understand it.

We have a lot of center to top weight in ours and that roll over factor is much greater as it is off centerline.

If your weight is kept below centerline to the floor I personally see it would be no greater than having a cargo box on it loaded to top of the rails.

Still waiting for the video clip of jacking.

 

[LowTech]

The seat gets a permanent ridge as well.
We're going to have to put in captain chairs to to fix that issue now that we're back at base camp
.

 

[KsM715]

Okay, I am not that crazy. But it seems like somebody out there ought to be able to find it.


Thanks!


Spook.

There is no one specific angle that will cover all the 109's. Thats why its not in the manual. Motomacguyver stated it well. Its going to be truck and load specific.

Im willing to bet that in a slow and controlled enviroment your truck will ride at more of an angle than you feel comfortable with. Ad in speed and uneven off-road terrain and the angle will deminish significantly.

 

[AMX]

I have rolled a d6 dozer and a case backhoe in these mountains. It isnt the rollover that gets you, its the long fall on your head when you unbuckle the seatbelt.

 

[Recovry4x4]

Variables such as drivers and fuel load effect the maximum safe angle. So not only is it different for every truck, it changes on your truck as well. The same ° on one side won't be the same on the other side either. The jack idea is good, please take videos. FYI, where you place the jack between fore and aft will effect it too.

 

[Unforgiven]

Note, this is the static rollover maximum. That is, when the truck is not moving (or moving very slowly along a hillside in a straight line. It does not take into account the dynamic effects of turning the steering at speed.

I assumed by your question that this is what you were interested in ... how "steep" of a side of a hill can your traverse along a contour of equal elevation. That is, how steep of a hill can you cut across in a straight line without rolling over.

Cornering rollover angle is different & involves the previously discussed velocity equation given by BH.

 

[panshark]

Here's a thought, it could be completely dumb and non-functional, but here goes: how about a rollover warning sensor? rig it up to go off when there is very little pressure/weight being placed on one side of the truck. Unless you're running a Nascar circuit, you would want to rig up a system on each side of the truck (that way you can tell if you're going to tip either left or right).

You could have the sensors wired into the same buzzer, because let's face it, if you really don't know which side of your truck is likely to become airborne, you might have bigger problems than simply rolling the truck over.

I'm thinking about maybe a couple of sensors sandwiched in the rear leaf springs, if the wheel starts to "hang" from the springs as opposed to bearing weight, the contacts break, open circuit, and the buzzer sounds.

In my mind, this approach would provide more consistent results across a variety of duece applications and setups.

If this wouldn't work, please tell me so that I can learn.

 

[Unforgiven]

Or you could just use a mercury filled switch as a clinometer anywhere perpendicular to longitudinal axis of the truck. That way you wouldn't have to worry about false alarms over hummocky terrain.

 

[panshark]

i was thinking about the false alarms as well, perhaps you would have to rig the alarm so that both of the rear wheels would have to start to hang. so, when you have 2 open circuits on one side, the alarm goes off.

I'm basing this design on the logic that under normal off-roading conditions, when one tandem goes light, the other tandem is simply that much heavier. Unless, of course, you're about to smack a mirror on the ground.