Lifting capacity

[MossRoad]

Isn't the standard ...?

You have summed up the potential Power Trac owner's puzzle quite well with those three words!

 

[J_J]

Isn't the standard the weight that can be lifted 500 mm out from the attachment point, and the attachment weight has to be subtracted from that?

On my b3030, I haven't put the rear wheels in the air. Have come across situations where the bucket wouldn't lift while digging. The hydraulic relief gave. Not sure if that will be helpful. It certainly seems reasonable to me that a Powertrac would need weight in the rear, but I'm coming at that from a CUT perspective - never owned a PT, but I think they look neat and I sure would love to play with one.

I believe that the greatest lifting capacity is at the point where the hydraulic cylinders contact the lifting arms, or behind the lifting point. You have to work out the math to add distance from the point of contact. Theoretically, if you have a 3000 lbs lifting cylinder, it will lift 3000 lbs, plus maybe some reserve. What would the lifting capacity be at 1 ft, 2 ft, etc. An analogy might be something like, a person might lift a 5 gal bucket of water, up close the the body, but try to lift the 5 gal bucket of water with a straight arm. Very difficult. The further out you try to lift, the load capacity will decrease

 

[MossRoad]

That's a good analogy, J_J. I ran into the same questions when designing the backhoe and figuring leverage. 1 foot of mast on either side of the pivot point = 1:1, so a 30,000 pound cylinder could provide 30,000 pounds of force on the other end. 1 foot of mast on the cylinder side and two feet of mast on the other side of the pivot point = 1:2, so only 15,000 pounds of force on the other side. 1:3 gets you only 10,000 and 1:4 only gets you 7500.

You have to figure out the power of the lifting cylinder and then all the distances to pivot points, then the counterweight of the tractor with our without operator, etc...

All I know is our little PT425's hydraulics will lift the rear of the tractor off the ground if any attachment is stuck under an imovable object. I can keep adding weight until the thing either hits the reliefs or snaps in half, whichever comes first. I don't want to find out . A heaping large material bucket full of stones is plenty of bite for me, thank you.

 

[Charlesaf3]

I believe that the greatest lifting capacity is at the point where the hydraulic cylinders contact the lifting arms, or behind the lifting point. You have to work out the math to add distance from the point of contact. Theoretically, if you have a 3000 lbs lifting cylinder, it will lift 3000 lbs, plus maybe some reserve. What would the lifting capacity be at 1 ft, 2 ft, etc. An analogy might be something like, a person might lift a 5 gal bucket of water, up close the the body, but try to lift the 5 gal bucket of water with a straight arm. Very difficult. The further out you try to lift, the load capacity will decrease

Yes, I understand that - hence the standard being half a meter out from the lift point. It seems agreed that that gives a fair point of comparison for real world usage, as very few of us actually lift from the bottom of the cylinder... So by standard, I mean across tractor lines

 

[BobRip]

On welding cast iron. I believe that you have to heat up the cast iron with a torch before you start welding. I don't know the correct temp. You could just bore some holes in it and bolt on some plates.

I know they heat up engine blocks before they weld

I did a little research on welding cast iron and it was confusing. One said to heater to 400 to 1200 deg. F, another said 100 F was OK, another said cold was OK. Another said weld only about one inch at a time. I did this, so maybe I am OK. I pulled on the weight real hard and did not get any movement or breakage. A little cracking in this application is probably not going to hurt. Does anyone have an more experience in this area?

 

[J_J]

I did a little research on welding cast iron and it was confusing. One said to heater to 400 to 1200 deg. F, another said 100 F was OK, another said cold was OK. Another said weld only about one inch at a time. I did this, so maybe I am OK. I pulled on the weight real hard and did not get any movement or breakage. A little cracking in this application is probably not going to hurt. Does anyone have an more experience in this area?

Bob Read this article.

The most important thing for you to understand is that electric welding on cast iron is actually the very worst decision you could make to attempt to repair your cracked cast iron part. If you want to make a complete mess of your part, go ahead and arc weld it with nickel rod. Cast iron cannot stretch and withstand the contraction and hardening caused by cast welding with preheating below 1200 deg. F. The brand of welding rod does not make a very big difference. It's the heat that causes the changes to the cast iron itself. Sure the nickel weld is machineable but the cast iron will become as hard as a drill bit or tap and therefore will prevent the proper machining that is often required. 50% of the casting repairs we see have been arc welded on with disastrous results often costing the owner at least twice as much to repair properly. Cast iron welding should not be attempted even by experienced welders without years of high temperature oven welding training. Cast iron requires preheat of at least 900 deg. F. for brazing and 1300 deg. F. for fusion welding

 

[bbabineau]

I believe that the greatest lifting capacity is at the point where the hydraulic cylinders contact the lifting arms, or behind the lifting point. You have to work out the math to add distance from the point of contact. Theoretically, if you have a 3000 lbs lifting cylinder, it will lift 3000 lbs, plus maybe some reserve. What would the lifting capacity be at 1 ft, 2 ft, etc. An analogy might be something like, a person might lift a 5 gal bucket of water, up close the the body, but try to lift the 5 gal bucket of water with a straight arm. Very difficult. The further out you try to lift, the load capacity will decrease

I understand the concept but have no idea how to calculate; however, in the attached photo I was lifting a 400 lb beam at the tip of the boom. The beam is 14 ft long so the center is at 7 feet. I had no feeling of tipping, in fact I carried two of these beams off the trailer at one time and had no sense at all of being light. I did not try three as that would have been at the total advertised capacity and I did not want to try it.

 

[J_J]

Does everyone know that the PT's lifting setup is a Class three lever setup, which has a fixed fulcrum point, fastened at the frame., The point where the hydraulic cylinders connect to the arms, is called the effort. The load is the third part of the lever, and on the PT, I believe, that it is the point where the Quick Attach is connected. Feel free to correct my observations.

 

[J_J]

I understand the concept but have no idea how to calculate; however, in the attached photo I was lifting a 400 lb beam at the tip of the boom. The beam is 14 ft long so the center is at 7 feet. I had no feeling of tipping, in fact I carried two of these beams off the trailer at one time and had no sense at all of being light. I did not try three as that would have been at the total advertised capacity and I did not want to try it.

Which model PT do you have. I can see that it is red.

 

[BobRip]

Bob Read this article.

The most important thing for you to understand is that electric welding on cast iron is actually the very worst decision you could make to attempt to repair your cracked cast iron part. If you want to make a complete mess of your part, go ahead and arc weld it with nickel rod. Cast iron cannot stretch and withstand the contraction and hardening caused by cast welding with preheating below 1200 deg. F. The brand of welding rod does not make a very big difference. It's the heat that causes the changes to the cast iron itself. Sure the nickel weld is machineable but the cast iron will become as hard as a drill bit or tap and therefore will prevent the proper machining that is often required. 50% of the casting repairs we see have been arc welded on with disastrous results often costing the owner at least twice as much to repair properly. Cast iron welding should not be attempted even by experienced welders without years of high temperature oven welding training. Cast iron requires preheat of at least 900 deg. F. for brazing and 1300 deg. F. for fusion welding

I appreciate what the article is saying, but what I am welding is not as critical as say an engine block. I will not be drilling and tapping it or machining it in anyway. I just want it to stick to other metal. Given that is there still a problem? J_J, I am not trying to be difficult here, it just seems that for my limited application there is not really an issue. Or is there?