Near disaster at Outlaws pull July 14, 2023 01:48PM
video: [youtu.be]

Ulmer accident. Lucky someone didn't get hurt bad.

Re: Near disaster at Outlaws pull July 14, 2023 02:01PM
Yes I agree, it probably wouldn’t hurt to crawl under and inspect the hitches every now and then , also I never understood why it’s ok at a lot of pulls to hang out at the end of the track it doesn’t matter the organization it should not be allowed!

Re: Near disaster at Outlaws pull July 15, 2023 02:08AM
He did a great job of driving to avoid disaster.

Re: Near disaster at Outlaws pull July 15, 2023 03:04AM
Quote
Jimmy
He did a great job of driving to avoid disaster.

That's right. Tyler really kept his cool there. I'm not sure it would even be possible to do a better driving job than that.

Re: Near disaster at Outlaws pull July 15, 2023 02:29AM
Close call.There should be absolutely nothing at the end of the track,no haulers, no vehicles of any kind,no track prep equipment,no people,etc..My home town pull is fortunate enough to have 400 ft plus of shut down area thats kept open..Many years ago a puller in Kansas rolled his Mod and ended up dying trying to miss someone parked at the end of the track.

Re: Near disaster at Outlaws pull July 15, 2023 10:36AM
Outlaws allegedly use a second hitch.
IF the second hitch was part of the same assembly that fell off in a pile, a second hitch is worthless.
Maybe some specifications of construction of the second hitch are in order.

Re: Near disaster at Outlaws pull July 15, 2023 06:27AM
Quite impressive to watch this. A few conclusions and my 2 cents.

The braking capability of pulling tires is quite zero, because braking acts with the thread pattern, not against it.

Just look at his helmet, when she starts to accelerate free, it is pressed against the ROP, that tells how much potential is in that kind of situation.

The reaction time is really short, most younger people need between 0.5-1.0sec to realize what's going on there, if they are GOOD at it. And I expect that somebody lazy or older needs at least 1.2-1.5sec until he reacognize what's up.

Assuming that the difference between short (0.5sec) and long (1.5sec) reaction time is a whole second, and the freely traveling vehicle is at around 35-40mph, this one single second leads already to a distance difference of around 50-55ft.

It seems that it happened at about 2/3 of the nominal pulling track distance, the initial velo is of appr 18-24mph.

That leads to concerns into two different directions. First, what would have happened at a few more distance, lets say at 80-90% of the nominal track length, although the traveling speed would already have dropped a bit, onto lets say 14-18mph?! Secondarily, try to sense the importance of hitch plate inspection before indoor events.

Re: Near disaster at Outlaws pull July 15, 2023 07:26AM
Why didn't the secondary hitch not function properly?


Answer : There wasn't one!

Bottom line,...if that tractor would have been at a minimum of a 30 degree angle to the chalk when the hitch failed,...it would have been sitting on top of people. And this subject of how great a job the driver did would be in a court of law..........

Re: Near disaster at Outlaws pull July 16, 2023 02:21AM
never have seen a second hitch not part of main hitch

Re: Near disaster at Outlaws pull July 16, 2023 02:55AM
You must not look at many 2wd and 4 wd trucks.
There was a design of 2nd hitch proposed years ago, that would have kept this from happening.

Re: Near disaster at Outlaws pull July 16, 2023 05:04AM
trucks have much more room and space for much safer hitches than tractors with the rear end right there

Re: Near disaster at Outlaws pull July 16, 2023 05:22AM
What actually failed on the tractor? Would be good to know to possibly help prevent this from happening again.

Re: Near disaster at Outlaws pull July 16, 2023 08:18AM
one video I watched had a pile of steel hooked to the sled, piled up mess on the sled's chain.

Re: Near disaster at Outlaws pull July 17, 2023 02:13AM
Think one minute more about the whole stuff made me recog the beauty of physics behind the actions within the very first 1.0-1.5 seconds of such an event.
Assuming that the train ran with 18-20mph, the wheel circumference speed has been appr 50-55mph. What happend after releasing the vehicle, is that the stored kinetic energy in all rotational parts relative to their inertia and rotational speed, is trade for accelerating the vehicle in translatory motion.
Parts which contain significant kinetic energy are the wheels, all drivetrain components and rotating engine parts.

Quick and roughly estimation.

tractor weight: 7000 lbs
wheel circumference speed: 56 mph
initial train velo: 20 mph
rear wheels and drivetrain inherent kinetic energy: 3.4E5J
velo drop in drivetrain: 40%
corresponding energy delta: 2.1E5J
final translatory velo: 33 mph

Guess how big the margins of kinetic rotational energy is for on one hand rear wheels, and on the other hand for crank and clutch pack ;-)

Re: Near disaster at Outlaws pull July 17, 2023 06:31AM
That is an interesting approximation, but the one key factor missing, is the driver did not get out of the throttle for a few tenths of a second, so energy was still being supplied to the drivetrain.



Edited 1 time(s). Last edit at 07/19/2023 10:53PM by RCP.

Re: Near disaster at Outlaws pull July 17, 2023 07:05AM
it takes "TIME" to react

Re: Near disaster at Outlaws pull July 17, 2023 07:35AM
I would guess the kill switch activated before he backed off the throttle.

Re: Near disaster at Outlaws pull July 17, 2023 08:22AM
Quote
Dirtfarmer
I would guess the kill switch activated before he backed off the throttle.

Thats for sure... on one hand. But there're also 2-3feet between the point where she got released, and the kill switch cable had been fully tensioned until it finally pulled the plug.

Re: Near disaster at Outlaws pull July 17, 2023 04:13PM
Carlsson, in this part of the US, the sled can make even the 'lower' hp classes easily run 18-24 actual mph. A lot of classes are in the very high 20's (meaning like 28 - 30, which actually is quite normal).
And you take those really high hp classes and they can certainly all clispse into the low 30's mph. Which certainly a strong alky LSS, which I believe was the tractor in this video, fits this speed scenario.

IPL (Indiana Pulling League) uses a mph / distance board on all their classes. You can see those figures the whole distance of each hook - from start to finish - and then it gives the final top mph & distance. I really like it and I miss it when I go to NTPA and PPL events. I normally take a photograph of each puller's stat. Go to my website and you will see them for most IPL pullers (sometimes I forget or get to visiting and fail to get a pict of the stat). You may be surprised how fast those 'low to moderate' hp classes are actually going. '23 IPL, look @ Idaville & Peru & Arcola.

www.DaveDannPhotos.com

Another long day - time for bed. Hopefully tomorrow I will get NTPA Charlotte, MI photos posted. Wolverine Pullers do have a digital distance display and I got most of those photos.

Re: Near disaster at Outlaws pull July 17, 2023 05:26PM
Thank you Dann, glad that somebody is also interesting in some of the fundamental physical items to observe. I've heard about that some teams already tried to get some similar things right off their tractor, via acceleration sensors and/or gps. From my point of view, this should be something every sled team must be interest in, for their own purpose and development. As well as the clubs and sanctioning bodies must be interested of to just have these numbers in the drawer on demand, detecting unwanted tendencies etc.
For the above mentioned numbers, I won't let it look over-dramatized. But my calc table can also handout values for higher initial train velos, Maybe I can send it to you via pm.

Re: Near disaster at Outlaws pull July 17, 2023 06:39PM
Quote
Carlsson
Thank you Dann Dave, glad that somebody is also interesting interested in some of the fundamental physical items to observe.

too late or early to write properly, sorry for that.

Re: Near disaster at Outlaws pull July 19, 2023 06:15PM
Kill switch kills the engine the instant the tractor is removed from the sled Winking

Re: Near disaster at Outlaws pull July 20, 2023 02:19AM
I'd be interested in seeing the data.



Edited 1 time(s). Last edit at 07/20/2023 02:20AM by MLP.

Re: Near disaster at Outlaws pull July 20, 2023 02:16AM
Also, don't forget that wheel slippage changed from 50% to zero.

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