Lifting Heavy Objects

BobRip · Jul 9, 2005

If you want to lift something heavier than the 800 pound limit on a 422, you could attach a chain or rope to the middle of the lift arm. This would give you more lift capacity, but with less lift height. You could also weld some chain hooks onto the lift arm and make it a little easier to connect chains. Has anyone tried this or something similar?

Bob Rip

cqaigy · Jul 10, 2005

Seems like if your logic is correct. However, seems you would be putting more weight on the front tires.

FOURTEEN · Jul 10, 2005

( Has anyone tried this or something similar? )


 NO!
Because the Attachment Plate is the lifting point designed by PT.
Lifting capacity is usually limited by the counterbalancing weight of the PT. (This is a useful safeguard! When I first got my PT I wondered what would bend, break, or fail if I attempted to overlift with it. I soon learned to my great relief that nothing bad happens - the rearend just starts to raise off the ground.)
Lifting part way back on the arm would usually cause interferance between the PT body and the load.
Lifting by just one arm could twist and damage the arm assembly.
Lifting by the crossmember could bend it, or overload other expensive parts.
Lifting by or near the toggle could bend or damage it.
It is better to not lift something than to damage the PT trying!

Lift with the lightest attachment possible. The Grapple Bucket will lift the least. The LM Bucket will lift more. The Forks still more. The Potato Digger even more. But the bare Attachment Plate will lift the most.

Keep the lifting point of the load as close to the Attachment Plate as possible. Don't lift with the Fork tips.

PS: This is my Power Dump Trailer. Since a full load of mulch weighs about 3000#, my PT-425 may be lifting close to 1000# at the Attachment Plate to tip this remaining load up!

J_J · Jul 10, 2005

Bob,

Although it would be impractical. the greatest lift would be at that point where the cylinders attaches to the lift arms, or closer to the frame. If each cylinder has a lift capability of 5000 lbs, the total lift weight could be around 10,000 lbs if lifted at the cylinder attaching point across both lifting arms. The frame and wheels probably can not take that kind of force, and therefore is not mentioned. Apparantly, they have figured out a limit for a force at a distance from the fulcrum point to the ends of the lifting arms. I believe your machine is rated at around 800 lbs. My 1445 is rated at 1200 lbs. at the lifting arms ends. You can shorten the distance and lift more, or extend the distance, and lift less.

You could also get more lift by replacing the standard cylinders with larger cyl

Please correct me if I am wrong, but please be gentle.

BobRip · Jul 10, 2005

Thanks for the comments Fourteen. I would hate to seriously damage my PT.

Bob Rip

MossRoad · Jul 10, 2005

It is your machine to do what you want with... so go ahead and lift where you want... just don't reverse those wheels, you may damage something! /forums/images/graemlins/tongue.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/smile.gif

(Sorry, couldn't resist /forums/images/graemlins/grin.gif)

BAGTIC · Jul 11, 2005

I tried lifting an empty water tank last week. Don't know what it weighs. I'll need to measure the metals thickness and surface area to calculate it...as soon as the rain stops.

One thing for certain the hydraulics has the power to lift the rear end way up off the ground. Couldn't have turned over if I wanted to as the forks were firmly pinned to the ground.

BobRip · Jul 13, 2005

( Bob,

Although it would be impractical. the greatest lift would be at that point where the cylinders attaches to the lift arms, or closer to the frame. If each cylinder has a lift capability of 5000 lbs, the total lift weight could be around 10,000 lbs if lifted at the cylinder attaching point across both lifting arms. The frame and wheels probably can not take that kind of force, and therefore is not mentioned. Apparantly, they have figured out a limit for a force at a distance from the fulcrum point to the ends of the lifting arms. I believe your machine is rated at around 800 lbs. My 1445 is rated at 1200 lbs. at the lifting arms ends. You can shorten the distance and lift more, or extend the distance, and lift less.

You could also get more lift by replacing the standard cylinders with larger cyl

Please correct me if I am wrong, but please be gentle. )

JJ, I must have missed your comment before. You make sense. The wheels and frame would not handle the 10000 lbs. I must think about this a little longer. It does seem that if you use the 4 in 1 to help push the arm up, you could combine the lift force of the arm cylinders and the lift force of the bucket. However, the built in protection of the relief valves would not work. I don't think anyone should try this, because of potential damage, but maybe some more comments will help clarify and add data.

Keep the comments coming, but don't break your PT.

Bob Rip

KentT · Jul 13, 2005

Bob,

You bring up an excellent point... relief valves. It would seem to me that the relief valves for the lift arm cylinders would be set to prevent you from lifting something that would damage the tractor -- not relying on the seat of the pants "PT pucker factor."

As a simple example, I think if your PT was facing uphill on a steep slope, you could lift more than if you're sitting on level ground before the PT pucker came into play...

I think I've now read through this entire form at least a couple times, and I've not read of anyone talking about the relief valves kicking in when they tried to lift something -- only the PT pucker coming into play. This makes me wonder if:

(1) the bypass valves are actually set correctly to prevent damaging the tractor -- especially if adding more weight to the back of the tractor (such as you and only a very few others have mentioned) still doesn't cause them to bypass... On both my Kubota loader and the Henry loader that I had on an old Allis-Chalmers before it, I could frequently cause the valves to bypass when I tried to pick up too much... Note that this is not good for the system if you do it repeatedly, because it can send hydraulic pulses, causing the system to "shudder"...

OR

(2) maybe the PT pucker factor isn't REALLY the design limitations of this hydraulic system, and perhaps the 800 lb rating (which seems somewhat accurate on where the pucker factor kicks in -- based on some anecdotal tests posted) is actually a bit higher than the pucker factor. I also wonder if that rating considers the geometry of the PT tractor design itself, where most of the weight is far behind the lift arms as ballast. Surely the standard rating system used would take into consideration the design of the tractor...

BOTTOM LINE: It would seem to me that those valves SHOULD be set to bypass somewhere around 800 lbs, if that is truly the rating for this system...

Yet, how may people have reported their lift valves bypassing, rather than the tractor attempting to pick up the load, and instead picking up the rear of the tractor????

Once I get my PT 425 home, I think some experimentation is in order....

BTW, this has nothing to do with whether or not the lift arms themselves are rated for more than 800 lbs -- you might bend them, for example -- only what are the real design limits for the hydraulic lift system...

J_J · Jul 14, 2005

Have you noticed that when pull back on the joystick, you hear that sound that sounds like a squeal. that is your valves bypassing, or relieving. Those cylinders can lift a much greater load, but the design limits you to a perceived safety factor, which is the back end rising. I have never lifted the back end of my 1445, because the relief valve comes on. I think my machine weighs in at about 3700 lbs. Someone has added some weight to their 425, and I would bet that he can lift more than 800 lbs. You can look up the push and pull limits for your cylinders, and that will give you an idea of your true limits, keep in mind the fulcrum effect.