Anyone put larger rams on their bx24 FEL arm?

[bx24]

At this point, I think I would rather push the physical strength of the steel more than I would l like to stress the rest of the hydraulic system. I am not so much concerned about any of the hydraulic cylinder issues (or the associated structure) with a higher setting on the PRV, but I would be concerned about the HST.

As I mentioned in the earlier post, where the FEL arm attaches to the vertical frame by the driver, this flexes a lot. Kubota obviously felt the same way given the extra support they put on the B21. That FEL does not even come off and they felt that they had to reinforce this area structurally.

I too get somewhat frustrated that I cannot lift a bucket full after plowing into the pile. At this point, I pretty much have my mind made up so we'll all find out shortly. As far as the warranty goes, if anything happens, the old rams go back on ;-)

The other thing that comforts me is how most of the machines I have run in the past (big wheel loaders, BH's and Bobcats), virtually all of them had more power than their weight could handle. With the added support from the FOPs and bar running to the front bumper, tipping forward will be my biggest issue.

 

[KeithInSpace]

A question: Why would you need to pursue a new PRV or otherwise alter your hydraulic system? The lifting force from a hydraulic ram is a matter of PSI on the ram itself...larger ram gives you more "I's" to go along with your "P's"...that's why you can pick a car up with a car jack. As I said before, it would take more fluid, but that is your loss in energy.

No reason in my mind to impact/risk the rest of the system. But I'm no expert.

Sounds like it's worth a shot, at least.

Adding the FOP sounds great...the real fireworks start when you remove or alter the existing ROPS. You may end up with a 4,500# Apocolypse-worthy war-machine when you're done that may need to get shifted into low range to get up your trailer ramp, but that's the beauty of these machines.

It'll take it.

Probably.

I think.

 

[Singlecoil]

I too get somewhat frustrated that I cannot lift a bucket full after plowing into the pile. At this point, I pretty much have my mind made up so we'll all find out shortly. As far as the warranty goes, if anything happens, the old rams go back on ;-)

I have the same frustration. It seems like if it was just a little bit better it would be a lot more useful. If the spoil pile got rained on I can't lift a full bucket? C'mon. Please keep us updated on how this project comes along and how much it cost.

 

[Harry c]

BX24 wrote:

I am not so much concerned about any of the hydraulic cylinder issues (or the associated structure) with a higher setting on the PRV, but I would be concerned about the HST.

The HST has its own hydraulic pump and pressure relief valve. The output of the accessory (for lack of a better term) hydraulic pump for the implements is fixed and is only about 6 gallons per minute at about 2,000 psi at full engine speed. That would translate to about 8 Horsepower (without doing the math). Obviously the tractor can put more than 8 hp to the ground. The HST has a variable displacement pump that drives a shaft-mounted hydraulic motor to drive the wheels. As you press the footpedal farther a "swashplate" is tilted and the pump puts out more volume. If you push the pedal too far under too much load the pressure gets too high and the relief valve opens. All this is inside the HST housing. The accessory hydraulic pump is actually mounted on the outside of the HST housing. I haven't totally analyzed the HST part drawings, but I don't think the accessory hyd pump has any effect on the HST outside the fact they share a common fluid sump. The pressure relief valve on the accessory hydraulic pump is adjusted by putting shims behind the relief valve spring. Kubota offers these shims in three thicknesses, .01mm, .02mm, and .04 mm. You can stack combinations to get whatever thickness, therefore pressure you need.


Keith I.S. wrote:

A question: Why would you need to pursue a new PRV or otherwise alter your hydraulic system? The lifting force from a hydraulic ram is a matter of PSI on the ram itself...larger ram gives you more "I's" to go along with your "P's"...that's why you can pick a car up with a car jack. As I said before, it would take more fluid, but that is your loss in energy.

Keith, you are exactly right. More I's give you more lift. But more Ps give you more lift too. If you increase the pressure, you don't need to increase the cylinder size and you don't affect the speed. If you increase the cylinder diameter you don't need to increase the pressure but you reduce the speed. As noted above, no new PRV is required. I can't imagine the shims could cost more than a couple of dollars even from Kubota!

I'm not advocating either change and don't often run into a situation where a few pounds one way or the other is really an inconvenience. I've only had a real problem once and I found out later that the cube of pavers I was trying to lift weighd over 1,300 lbs so neither option would have helped. I've never bumped a hydraulic system pressure more than 200 psi above its rating.

 

[bx24]

Taking a rough guess, I am hoping the FOP will only add about 50 lbs. I know I am opening up another can of worms here, but when the new FOP goes on, the old ROPs comes off. My goal is to make it a virtual twin of the B21 from that standpoint.

I have read that the ROPs is made to "give" when the tractor rolls (to absorb energy???? I live near the Indy Motor Speedway so I understand destruction for the sake of energy absorbsion). Are FOPs designed the same way or are they made to be simply strong and rigid through gussets on the corners etc. My gut tells me strong and rigid is better but who knows. At any rate, mine will most likely end up rigid enough to pick up the whole tractor by the FOP (not that I plan on trying ;-) )

 

[bx24]

Harry-

Thanks for your input .... I understand hydraulic concepts much better their physical makeup (at least when it comes to the HST and pump side). With everything else pretty much made up in my mind, the only thing that still slightly bothers me is the excess strain the fulcrum (otherwise known as the front axle). Since both my front tires have slow leaks, they usually serve as pretty good stress indicators based on how much they flatten out when lifting heavy stuff. (God forbid that I actually fill them up ....)

 

[Harry c]

BX24,
Sorry, no knowledge of the capacity of the front axle. I'm always careful any time I'm hauling a really heavy load in the FEL. There's a bunch of pressure on the machine when you hit a big bump while carrying a heavy load.

I forgot to mention, I haven't checked, but the backhoe is probably on the same PRV as the loader so any pressure increase will be felt at both ends. There could be another relief valve on the backhoe control valve stack. Again, I haven't checked...

 

[bx24]

The more I think about this, the more I am leaning towards the larger rams.

Solution Larger Rams More pressure

More lift More lift (same for both)
More tractor stress More tractor stress (same for both)
Slower cycles Same or faster cycles (FEL lift cycle time)
Same HD stress More HD stress
No changing the PRV Modifying the PRV (settings)

With the PRV modification, I still get the structural stress but I could potentially also get HD system stress. I can weld, but rebuilding HD systems is beyond my current abilities.

 

[bx24]

Let me try posting this table again (the tabs did not work the first time ...


Solution ............... Larger Rams .......................More pressure

.................................More lift ................... More lift (same for both)
.........................More tractor stress ........More tractor stress (same for both)
...........................Slower cycles ............Same or faster cycles (FEL lift cycle time)
.............................Same HD stress ................More HD stress
.......................No changing the PRV ..........Modifying the PRV (settings)

 

[Berniep]

If you plan on doing 200 miles an hour across that yard of bricks then I would say make the fops flexible. Otherwise I don't see that a tractor has enough speed to require any crumple zones.