Given the current prices in 2025, what are your thoughts on PT422 over PT425?

[ponytug]

I don't get that. When you use a loader bucket and drive into a material pile or virgin earth, then curl the bucket back to lift and fill the bucket as your driving in, I stall out the hydraulics (relief valve opens). To me that puts as much stress on everything. When Leverage comes into the picture (longer attachment), it just makes the relief valve open with less weight, you don't get to work it harder/lift more utilizing the leverage. It works against your capabilities. Using arbitrary numbers, if the relief opens at 100 psi, the front end loader linkage sees a consistent pressure in relation to the 100 psi of hyd pressure. It is the same with a bucket, forks or excavator. The only time this would be an issue is if there is no circuit relief, that is needed when the control valve is in the closed position (oil locked into lift cylinder, hose and deadheaded at valve) and you apply greater force. Like when carrying a rock and you hit a pothole. Machines like John Deere have a relief valve to unload this force. Not sure if PT has this and when I think they engineered leakage into the system, this may be the reason (this is why a raised bucket will be on the ground in a short period of time).

Might there be an issue with the intermittent shocks as a bucket is pulled through gravel or uneven soil? I could see that at the same hydraulic pressure relief that might be more shock and torsion on the rollover with a backhoe.

All the best,

Peter

 

[m5040]

Might there be an issue with the intermittent shocks as a bucket is pulled through gravel or uneven soil? I could see that at the same hydraulic pressure relief that might be more shock and torsion on the rollover with a backhoe.

All the best,

Peter

Yes, I was up half the night thinking about this. We should probably start a new thread on the need for and adding a circuit relief. I think they are mostly needed in 2 circuits, the bucket curl (aux circuit) and the attachment curl back (Z bar piston). The aux circuit bucket curl is needed because the PT could use the tractor traction to pull the bucket through the dirt with a locked/closed hyd circuit and no relief. And as we discussed, the attachment curl-back which would be most noticeable when using an excavator attachment with thumb and carrying a max capacity object over rough terrain.

 

[ponytug]

Yes, I was up half the night thinking about this. We should probably start a new thread on the need for and adding a circuit relief. I think they are mostly needed in 2 circuits, the bucket curl (aux circuit) and the attachment curl back (Z bar piston). The aux circuit bucket curl is needed because the PT could use the tractor traction to pull the bucket through the dirt with a locked/closed hyd circuit and no relief. And as we discussed, the attachment curl-back which would be most noticeable when using an excavator attachment with thumb and carrying a max capacity object over rough terrain.

Yes, we probably should.

I think that relief when filling cylinders is one thing, but a relief on a filled cylinder might get one into safety issues. I have a vague memory of someone at Power-Trac telling me that the reason PT uses "leak down" type valves is to provide some pressure relief to prevent over pressure in the cylinders. It was mentioned in the context of warm cylinders cooling down and increasing the internal pressure and blowing out seals. I can imagine that using a leak down pressure relief might not provide enough relief for a loaded bucket over rough terrain. I don't see an obvious solution besides something electronic and complicated to hold position, but allow pressure changes, rather like kinematic GPS/laser control of leveling planes or buckets on work sites trying for highly defined, precise, and accurate grading, but using internal position encoders. Not cheap.

All the best,

Peter

 

[2manyrocks]

There is a lot of strain digging with a backhoe bucket, especially when rocks and tree roots are involved. PT mini hoe design appears to reply on turning the PT to dump material to the side. There are no outriggers on the mini hoe to distribute the force of digging to the ground.

One reason I dont own a 3pt backhoe is I was warned tractor rear ends have been known to break due to the forces involved.

 

[MossRoad]

There is a lot of strain digging with a backhoe bucket, especially when rocks and tree roots are involved. PT design appears to reply on turning the PT to dump material to the side. There are no outriggers to distribute the force of digging to the ground.

One reason I dont own a 3pt backhoe is I was warned tractor rear ends have been known to break due to the forces involved.

There's the mini-hoe, which attaches to the Quick Attach on the FEL arms like any other PT attachment. It's basically just the dipper stick and bucket. You have to turn and/or drive the PT in order to move it side-to-side.

Then there are the full backhoes on the 2400 series machines.

 

[2manyrocks]

There's also a huge difference in force required to dig compacted soil versus lifting something that has already been severed from the ground like a section of downed tree trunk.

 

[MossRoad]

There's also a huge difference in force required to dig compacted soil versus lifting something that has already been severed from the ground like a section of downed tree trunk.

Kinda/sorta.

Here's why I say that.

If I bury my forks in the ground, then try to lift, the rear tires come up off the ground (the infamous PT pucker).

If I push my forks under a huge log, then try to life, the rear tires also come up off the ground.

If I toss bags of cement onto my lifted forks until the tractor tips forward until the forks hit the ground or trailer, and the rear tires come off the ground, the tractor does not feel(experience any forces) any different from the other two examples.

It just doesn't. I think we can all agree that once the weight of the machine is overcome by the inability to lift the load the forces don't change after that.

The forces that can change are in the dump/curl motions, and side-to-side motions.

I have buried my forks in the ground, under immovable objects, and rocked the dump/curl back and forth to the point of bending the forks. That motion can change the geometry between the point of impact and the mounting point of the base of the FEL arms on the machine quite significantly. That could increase forces dramatically.

Also, side-to-side motion can put side forces on the FEL arms, and those can vary depending on the extension of the implement and point of contact with the immovable object.

So I can see how the mini-hoe could change the forces between the bucket and the FEL mounting points. Now, there are TWO places you can change the geometry; the original dump/curl point at the Quick Attach, and the dump/curl point at the mini-hoe bucket, so even more chance of high loads and dramatic changes in just short movements.

A fun example:

Load 800# of cement bags on the back of the forks right at the QA point and see how many bags you can stack until the rear tires lift off the ground.

Now stack the cement bags way out on the tips of the forks. You can only stack about half as many before the rear tires lift off the ground.

We all know that's due to leverage and the distance of the weight from the fulcrum, which in this case, are the front tires.

The front tire fulcrum doesn't care about the length of the lever. It still feels the same load.

The FEL arms don't care either. They feel the same load.

The only thing that cares is the forks and the QA area, as that is also a lever and fulcrum. The farther out on the tips of the forks puts more strain on the forks and changes the leverage of the fork quick attach female socket against the male QA plate on the FEL arms.

Anyhow, it's an interesting discussion.

 

[2manyrocks]

In the course of digging a trench, there are going to be more repeated cycles of stress on the loader arms than a one off attempted lift of something that's too heavy. Might also consider measure where the forces are applied at the length of the digging arm versus the forks if you happen to know those measurements, I don't.

But use your PT425 as you wish. Not doing that to my 1445.

 

[MossRoad]

Sure, it's repeated stress to lift the rears off the ground. I've done it hundreds if not thousands of times. Each time I do it, it's no more stress on the tractor than the last time. That's what I'm getting at.

It's just a teeter totter.

The stresses that vary are when we change the angle or distance with the curl function. That affects everything from the FEL mount points to the point where the implement hits the resistance object. (and of course, side-to-side movements put side loads on the FEL arms, that's a given).

So in regards to the mini-hoe, if you push out or pull in the dipper stick with the dump/curl function on the joystick, or curl or dump the bucket itself, that changes forces. Just lifting doesn't change anything behind the front tires as that's just the fulcrum.

 

[2manyrocks]

$15,900 teeter totter plus delivery. There are no stabilizer arms to transfer the forces of digging to the ground so all the force is on the mounts and the tires and the wheel motor axles.

Take a shovel and pick up a shovel full of loose dirt. Then try sticking that shovel into compacted soil and lifting it. Same shovel.