Estimating center of gravity John Deere 790

[zzvyb6]

If it's a dual axle trailer, the simplest measure can be made by:
1) with the trailer unhitched, use some ballast to balance the trailer tongue to zero hitch weight as best as you can. Ramps off or upright.
2) hook the trailer back up and slowly crawl the tractor forward until the hitch weight goes from negative to positive. You need to have the ramps in the off or upright position as in step 1
3) The tractor + loader combo's c.g. will be located where it passes by the walking beam center, as there is no pitching moment at this point.

 

[ljjhouser]

I think you had it in post $8. Might go to a cat scale, unload the tractor at the station, and weigh front and rear axles with loader and any implement off the ground. Then measure distance between front and rear axle. The line between center of axles is a line that represents a fulcrum. The weight of each axle becomes the weight on each end of the fulcrum. With that, you can use math to find the balance point, or Center of Gravity.

Don't know if that helps. I think the cat scales charge about $12. Use the app - it is easy to get results. Also go inside and ask for the printout.

Or you could just load the trailer the way you want, take loaded to the cat scale. That will tell you how much of the total trailer weight has been added to the truck weight. That weight and the trailer axle weight represents the Total trailer (and load) weight. You should have 10-15% of that total trailer weight added to the truck for proper loading and tracking.

 

[LD1]

Even if you knew the precise COG that still dont help you with loading it.

IF you knew it, would you put that COG 1' foward of the center of the axles? 2' foward? Right in the middle based on the other junk in the front of the trailer?

GO to a scale, its cheap if you are that worried.

But we are probably talking about a light trailer and certainly a light (~3000#) tractor. And being towed by a 1-ton that could probably handle the entire load weight in the bed.

So IMO, anywhere between pulling the tractor all the way forward, and the center of the tractor roughly center with the axles. Somewhere between there is gonna give a positive tongue weight somewhere between a few hundred pounds and maybe 1500 pounds. All of which should easily be handled.

For me....I just measure hitch height if Im bumper pulling. 8k mini-ex on a 2400# 12k trailer.....I like to see somewhere between 1" and 2" drop at my hitch from empty vs loaded. Which on my mini ex puts the center point of the machine about right at the front axle. Tows like a dream

 

[MTGreen]

I think some of these answers may be overcomplicating things. Most tractors are designed to be heavier in the back end than the front end for a number of reasons. Center of gravity is an engineering calculation that's not published by manufacturers. One could go to great lengths to figure it out but from a practical standpoint having an exact figure isn't necessary to loading a trailer.

Just back the tractor in to the trailer just past center over the axles with the butt end of the tractor facing forward in direction of the travel. You said you have an FEL so maybe bias it forward another 6-10 inches to compensate.
Then park the rig on a flat surface and look at what's sagging and what's mostly level. The front versus rear tandem wheels on the trailer and the rear of the truck. If something's grossly off then try repositioning.

Bumper pull trailers are supposed to have something like 10% of the trailer weight on the hitch. The biggest danger is putting too little weight on the hitch as that contributes the most to sway. If you put a little more than 10% on the hitch it's not that big of a deal unless your truck is sagging to the point that the steering starts to get floaty.

 

[super55]

I worked for years where I transported a Kubota L2500 w/FEL and loaded rears(about same size as 790) on a tandem axle trailer and it was the front wheels just slightly in front of the front duals. This was being done with 1/2 ton 2wd P/U w/o a towing packing and even a couple times back in the day with my little 4x4 s10 pickup.

 

[pretendfarmer]

Most tractors are designed to be heavier in the back end than the front end for a number of reasons.

Through a bit of research I found this to be true. There is a serious weight bias towards the rear for traction, which means I was really off in my guestimation of where the COG was.

Just back the tractor in to the trailer just past center over the axles with the butt end of the tractor facing forward in direction of the travel. You said you have an FEL so maybe bias it forward another 6-10 inches to compensate.

I cannot back the tractor into the trailer for a couple of reasons, most importantly that I have like 1/4" clearance at the door header with the ROPS crossbar removed and all the air out of the rear tires. Backing in will lead to contact.

Bumper pull trailers are supposed to have something like 10% of the trailer weight on the hitch. The biggest danger is putting too little weight on the hitch as that contributes the most to sway.

This I do understand which is why I am here in the 1st place. My enclosed trailer is "built out" a bit and so I am unable to pull the tractor in as far as I really would like to. I plan on changing this, but need to haul the tractor somewhere before I can.

 

[bcp]

Once upon a time, I saw some diagrams showing many tractors had their center of gravity very close to where the operator's feet rested. And they lived happily ever after.

Bruce

 

[MTGreen]

Through a bit of research I found this to be true. There is a serious weight bias towards the rear for traction, which means I was really off in my guestimation of where the COG was.

I cannot back the tractor into the trailer for a couple of reasons, most importantly that I have like 1/4" clearance at the door header with the ROPS crossbar removed and all the air out of the rear tires. Backing in will lead to contact.

This I do understand which is why I am here in the 1st place. My enclosed trailer is "built out" a bit and so I am unable to pull the tractor in as far as I really would like to. I plan on changing this, but need to haul the tractor somewhere before I can.

Are you able to put something heavy in front of the tractor when you pull it in to the trailer, maybe something you can put the fel on top of? I'm thinking something like a heavy box blade or equivalent size/weight object that you can lower the fel bucket on top of. That could help bias more weight forward

 

[pretendfarmer]

Are you able to put something heavy in front of the tractor when you pull it in to the trailer, maybe something you can put the fel on top of? I'm thinking something like a heavy box blade or equivalent size/weight object that you can lower the fel bucket on top of. That could help bias more weight forward

I have a bunch of tools, a work bench, supplies, etc. forward of the tractor.

I went into a deep dive on all of this and found some great information right on this site. The rule of thumb seems to be that the center of gravity of the tractor is right around the steering wheel area, not taking the FEL into consideration - which would skew it forward a bit. This means that the tractor COG as it currently sits in my trailer is centered over the rear axle, not between them. The loader probably balances it right over the axles. When you add the roughly 1,000-1,500 lbs of cargo ahead of the tractor, it would seem I'm probably looking pretty good.

I went ahead and measured how much sag I am getting in my suspension when I hook it up to the truck. I am dropping between 1.5"-1.75". I feel confident things are decently balanced. It just makes it hard when I have other stuff in addition to the tractor, and the tractor is back a few feet from where I'd normally want it.

 

[pretendfarmer]

Just thought I'd update the post. The trip went great. The tractor seemed to be in a good spot in the trailer and it handled very well.