Nick's new Ram 2500

[bcbender]

Id like to see em.. I've been thinking about doing that very thing.

I built a alum pad and turned an insert to use one leg for servicing my 250L

I can show some pictures if you like.

 

[BigPapa]

On the Atlas you linked to from ASE, the Atlas PK-OHX10000X, all four arms are 38.5" long, so theoretically, each arm would be rated at 2500lb.

From my very rough redneck calculations, based on a 149" WB, 8500lb truck weight, and the statements by two members that their very similar truck's front axle carries an average of 5200lb, the COG is at the backend of the front door handle. If you put the front pads on the control arms and the rear pads on the frame just in front of the rear control arm mount, your weight distribution will be right at 70/30. So, if your truck weighs 8500lb, there will be roughly almost 6000lb on the two front arms and a bit over 2500lb on the two rear arms, just under 3000lb on each front arm.

One of you engineer fellows feel free to correct me if I'm wrong.

 

[NIsaacs]

On the Atlas you linked to from ASE, the Atlas PK-OHX10000X, all four arms are 38.5" long, so theoretically, each arm would be rated at 2500lb.

From my very rough redneck calculations, based on a 149" WB, 8500lb truck weight, and the statements by two members that their very similar truck's front axle carries an average of 5200lb, the COG is at the backend of the front door handle. If you put the front pads on the control arms and the rear pads on the frame just in front of the rear control arm mount, your weight distribution will be right at 70/30. So, if your truck weighs 8500lb, there will be roughly almost 6000lb on the two front arms and a bit over 2500lb on the two rear arms, just under 3000lb on each front arm.

One of you engineer fellows feel free to correct me if I'm wrong.

The 70/30 is at the axles. When you factor in the 7' overhang of the bed, beyond the arm placement you will unload the front half. If you get balanced COG, there should be 50/50 at the arms attached at the upright.

 

[AH64ID]

The 70/30 is at the axles. When you factor in the 7' overhang of the bed, beyond the arm placement you will unload the front half. If you get balanced COG, there should be 50/50 at the arms attached at the upright.

Balanced doesn't mean 50:50 weight, it just means that the weight*arm is the same front to rear. That could be 5000lbs at 3' and 3000lbs at 5'.

 

[NIsaacs]

Balanced doesn't mean 50:50 weight, it just means that the weight*arm is the same front to rear. That could be 5000lbs at 3' and 3000lbs at 5'.

Right, but at the post, the weight needs to be the same front and back or it is not balanced. It has to be the same or the post will topple. When you factor in the different weight and arm length, the end result, is the same weight.

 

[BSeyler]

Id like to see em.. I've been thinking about doing that very thing.

I knew I had put some pictures on at some point in the past. The mower cradle is 1 1/2” square tubing, since it was on the metal rack. https://www.turbodieselregister.com/threads/attachments-for-lift.268827/

 

[NIsaacs]

Bud says the arms are all the same length on the Atlas. So to get balance at the post, the front and rear arms need 4500 lbs each on a 9k truck. By moving the rear arms forward, about 7' you get weight off the front half. The overhang of the bed counteracts the front weight. Just like adding a bumper pull trailer to your hitch, it will unload the front.

 

[AH64ID]

Right, but at the post, the weight needs to be the same front and back or it is not balanced. It has to be the same or the post will topple. When you factor in the different weight and arm length, the end result, is the same weight.

You end up with the same force, not the same weight.

Think about a 1' torque wrench and a 2' torque wrench. They both can apply 10 lb/ft at the socket but the 2' one only needs 5lb to get that done.

Bud says the arms are all the same length on the Atlas. So to get balance at the post, the front and rear arms need 4500 lbs each on a 9k truck. By moving the rear arms forward, about 7' you get weight off the front half. The overhang of the bed counteracts the front weight. Just like adding a bumper pull trailer to your hitch, it will unload the front.

The arms have to adjust, or you won't be able to lift most vehicles. So they are likely the same length fully collapsed or fully extended, but they are adjustable.

 

[BigPapa]

Yes, the length of the arms and the angle of the arms are adjustable. The minimum length of the arms is 38.5", max is 57".

It's going to take someone a lot smarter than me to figure it out on paper because my heads swimming now, but to get the COG of the truck at the center of the poles with the front lift point on the control arm, the front arms will be extended to @45", the rears at their max of 57", and the truck perfectly centered between the posts. Now, I THINK the difference in the length of the arms changes the torque force on the poles, so to get the torque on the poles even, the truck would have to be moved forward, I have no idea how much.

If I'm wrong, someone PLEASE step in here and correct me before I make a COMPLETE idiot out of myself.....

 

[SnoKing]

Yes, the length of the arms and the angle of the arms are adjustable. The minimum length of the arms is 38.5", max is 57".

It's going to take someone a lot smarter than me to figure it out on paper because my heads swimming now, but to get the COG of the truck at the center of the poles with the front lift point on the control arm, the front arms will be extended to @45", the rears at their max of 57", and the truck perfectly centered between the posts. Now, I THINK the difference in the length of the arms changes the torque force on the poles, so to get the torque on the poles even, the truck would have to be moved forward, I have no idea how much.

If I'm wrong, someone PLEASE step in here and correct me before I make a COMPLETE idiot out of myself.....

I think a load sensor in the end of each arm would be required to start the math equation! Or sensors to measure the load on the arms at the center posts or both, or maybe none of this?

 

[AH64ID]

It can be done with math knowing axle weight, wheelbase, and preferred jack points.

 

[SnoKing]

It can be done with math knowing axle weight, wheelbase, and preferred jack points.

And completion of Physics 101 to 404 training.

 

[AH64ID]

And completion of Physics 101 to 404 training.

Not physics, closer to calculus.. but not that hard either.

 

[bcbender]

Maybe this'll help. as has been said, you want to keep "whatever" vehicle's COG in the lift manufacturer's recommended space. so since the RAM trucks have a dedicated front lift point (RED ARROW) then one need only figure out where the COG is; and then set the (PURPLE ARROW) as the rear lift point to ensure that the front lift arm is not overloaded. Unbalanced lift forces are OK as long as not exceeding the lift SPEC and COG is in the proper location.

 

[BigPapa]

Not that simple when dealing with a long truck with a very heavy front end. The COG is the red line. Front pads at #2, rear pads at #1, rear arms will be all the way out and COG still in front of the poles. This drawing is on an asymmetrical lift, the one he’s looking at is symmetrical.

 

[AH64ID]

It is that simple, if the correct lift is purchased.

 

[bcbender]

Well good to know where the theoretical CAD COG is,..

I had always assumed the COG to be near the end of the front door handle and I line my handle up with the back side of the lift column just like I did on my 2004.

Center of mass is that simple, and calculating arm loading from a simple uniform beam loading calculation is also that simple. My Asymmetric lift allows for both COG locations as I showed above previously, so as long as I position my rear arms in the correct frame location, I can transfer some of the weight to the rear arms.

I would agree if one is lifting heavy trucks alot, more capacity lift is better; but if your "current" slab is not enough (min 4" for 10k and 6" for a 12k plus there are sqft requirements) it is possible to safely use a 10k for a 9k truck.

FWIW, I use position # 2 for the front pads, and one can then adjust the location of position #1. I also use frame cradles for the truck(s) not the flat pads to prevent the possibility of it sliding off.

 

[Topzide]

Here is the reason that if I can ever get a shop, I'd have a 4 post lift for my truck! I've used my FIL's 4 post with the center lift bridges. It's great for most things that I would be doing on truck or wife's vehicle. JM2C on lifts. Would just be happy if I could have a dry place to work in!

 

[AH64ID]

Using the specs (4658/2845) from Ram @NIsaacs trucks CG, based on new/empty, is 56.5" aft of the front axle (approx front door handle, as mentioned). So in theory if you line the front door handle up with the post then you will be in CG if you can reach adequate jack points with the arms.

At that light of a weight you will be within spec, but what does the truck weigh now?

I know that regardless of size of the 2-post I'd go weigh my truck to get a good idea on current CG.

 

[BSeyler]

When I got my lift, I did not want to have buyer’s remorse, so went and looked at several and talked to techs who were actually using them. A trip to a dealership and a visit with a tech who works on these pickups seems to me like a good move. For most of us, it’s a lot of money to lay out.