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| The scene of the extraction. 2' elevation contours. |
I had a chance to pull a car out of a ditch today.
No names will be used to spare hard feelings.
The vehicle was a light-weight sedan similar to a Honda Accord. It was two-hundred yards off the road and tipped nose-down into a drainage ditch. The front bumper was in the water and the rear end was about four feet higher in elevation than the front.
The kid was thorough, I will give him/her that.
Sprite let me use her tractor and insisted that she come along to see that we did it right.
Whaddya do? It is her tractor.
According to this document, the center-of-gravity is very close to the rear axle even for four-wheel-drive tractors. That is why conventional wisdom for pulling stumps and boulders out of the ground is to use reverse gears on an ag tractor.
Sprite insisted that we had to pull the car out using the drawbar and forward gears.
She said that the tires were loaded (meaning the rear tires were filled with a chloride solution to make them heavier) and that meant we could only pull forward.
Her tractor. Her rules.
We got the logging chain run. Of course I made the kid do the crawl-under-the-car part. I pulled it out at an idle in first gear. Plenty of time to push in the clutch if it started to lift the front end.
The tractor walked right out with the vehicle. No problem there.
After getting everything put back at Sprite's, I hopped on the internet and the general consensus is that if you don't know how hard the pull will be, to pull in reverse. Unless you are on a hill, it is almost impossible to flip a tractor over pulling in reverse.
It turned out well, but it was another one of those cases where somebody added apples to orangutans and got kittens. Maybe somebody told that to Sprite and it stuck or maybe she only heard part of a conversation.
I have been driving tractors for about 60 years and I have never had the front of a tractor raise if the pull was on a level, or nearly so, surface and the hitch was properly made on the drawbar which itself was in the proper towing position. I have know other men, and known of other men that were killed or injured by back-flipping tractors but in every case the hitch was improper or the pull was being made up a steep hill. And as you did always do the hard pull at idle or just above with your hand always on the throttle. Never rev it. The article struck me as being more academic theory that real life experience. --ken
ReplyDeleteCoyoteKen is correct.
ReplyDeletePulling in reverse puts a hard load on the front axle. You can break a front axle pulling too hard.
Pull from the rear, at just above idle, pulling from the drawbar, and you should never have an issue. Level-ish only.
Front axles are engineered to hold up the front and steer it, not as a hitch point.
ReplyDeleteIt would be pretty easy to engineer a new front hitch attachment point, but rigging it using stock existing metal - ungood.
The tractor has a front-end loader with a hay spear on the front. The loader has brackets with slots for chains. I my plan had been to "V" with the ends of the chain to the chain-slots brackets on the loader.
DeleteI assumed that if Kubota put brackets designed to accept logging chains they put enough beef into the loader and frame to support them.
That would probably work fine. Having a heavy loader like that would enable you to put some up-lift on something stuck, in this case a car, and "wiggle" it out of the mud to pull it out. If it can be done without tearing up the bumper and cowling. I use that technique for snaking logs out of the woods. Doing it a lot can cost you a drive shaft and differential spline and axel U joints for the front end though. They don't make those parts very tough. ---ken
DeleteIF the loader has brackets for chains from the factory (which I doubt, likely either the attachment is aftermarket or someone welded hooks to it) they are for LIFTING rather than pulling.
DeleteIf you are going to pull using forward gears, just remember to use the swinging drawbar, not the drawbar attached to a 3PH.
ReplyDeleteThe frame for a loader should be plenty strong enough, and put the point of force application close to the center of the tractor. Which puts the force on both axles. My Kubota would hit the limit of the hydraulics on the loader before it hurt the axles.
You raise an important point--hook to the draw bar and not to the 3PH attachment. That 3PH hook up unbalances the tractor and it's easy to do as I can fess up doing it myself on occasion because it's easier than bending over to get under it. Your loader points are well taken also. I never broke anything by overloading the loader but I moved a lot of rocks out of fence rows a couple of years ago and ended up getting the front differential of my J D rebuilt because of it. The coupling on the shaft is as hard as the spline of the differential so you end up replacing the expensive part also instead of just the cheap, easy part. Hauling logs in forks attached to the loader didn't help any either I suspect. --ken
DeleteMy experience with activities such as this are that with a tractor go slow. Low gear at idle or just above is safest. The peak torque is near the bottom of the torque range. It either will have enough traction and power to move the other vehicle or not. If you get the towed vehicle moving and it hits a snag, you have plenty of time to dump the clutch if you have successfully resisted the temptation to go wide open with the throttle. Most farm tractors have more power than they can use at the wheels because they are designed to operate power attachments. You are after the torque anyways because that is the leverage that moves the wheels initially.
ReplyDeleteNow, with a 4x4 and a snatch strap then momentum us king. All cars and trucks have massive amounts of power not needed nor are you able to put that power to the ground. Momentum or the accumulated kinetic energy of your vehicle's motion then released via an elastic strap will apply that multiple of your normal ft lbs of energy to the stuck vehicle all at once sometimes with very destructive results of the end of the strap is not attached to the proper spot either a frame or other solid bit.