BX25 FEL CYLINDER ENHANCEMENT

[Ductape]

I would check where your relief is set first. Sometimes they are very conservative from the factory. You may get what you are looking for just by bringing the pressure up some. Making new lift cylinders sounds awful expensive.

 

[swick1]

How much more do you want to lift? The 3320e only lifts about 1000lb and is a lot heavier.

I need to bump mine up about 200 lbs to make up for the weight of my pallet forks.

 

[Nightforce]

There's probably more than just a few of us who feel our tractors are "somewhat" under powered. While a good deal of Engineering goes into the design of our machines, a component of this is also safety and safety margins. When I engineer a machine or process, I target specific performance parameters. For these goals to be met, they have to be within the normal operating parameters which is neither at the absolute minimum or maximum for a particular device.

I have a Kubota BX25D. For the most part I'm very pleased with its performance but compared to other machines in this category in my opinion it suffers from "Homeowner Safety Limitations". Please keep in mind, I'm not trying to achieve the same performance as a Case 580, just a bit more than it has now.

Front End Loader

Lift Cylinder Specifications

Bore Diameter: 1.50
Rod Diameter: 1.0
Closed Center to Center: 20.50
Opened Center to Center: 33.5
Hydraulic Input Pressure: 1778psi (Factory Spec)

Since the lift cylinders are very small, my thought is to increase their size which will add capability. Initially I looked at a cylinder with a 2 1/2" bore. While this is a standard cylinder I did some calculations and was surprised at the capability of this modest change. To give you an example of how much pressures I'm dealing with a laid out the following chart in Microsoft Excel for the following cylinder bore sizes, all are in inches.

1.50
2.00
2.50

An additional component or approach to more capability of this discussion is increasing the pumps output pressure. As many indicated, adding a small shim under the relief valve spring. This approach increases the preload of the spring therefore increasing the amount of pressure the pump must produce. On my particular tractor for every additional 0.004 preload I can expect to see a bump in output pressure of 40 pounds.

This chart shows the increase in bore diameter I've listed above plus in incremental increase of .004 through .020 beginning with the factory 1778psi. The output pressure will most likely vary from machine to machine due to the acceptable range determined by the Engineering department.

 

[check]

I have a BX25 and I would be very hesitant about increasing the FEL lift capacity. When I carry something at the max my FEL can lift (e.g., wet sand), I can really feel the strain on the front end components, and I drive VERY slowly and carefully. I agree that the max is FEL lift capacity is inconveniently low on these things compared to other similarly priced brands, but I also do not want to bugger up my front drive train, wheels, bearings, axle, etc..

For MUCH better capacities, the B2650 is the way to go, but I tried it out, and it is just too big for my applications (frequently involving tight situations), and would cost me a good $20k or so to upgrade. So, I'm going with the "if it ain't broke, don't fix it" theory - at least for now.

 

[Nightforce]

I have a BX25 and I would be very hesitant about increasing the FEL lift capacity. When I carry something at the max my FEL can lift (e.g., wet sand), I can really feel the strain on the front end components, and I drive VERY slowly and carefully. I agree that the max is FEL lift capacity is inconveniently low on these things compared to other similarly priced brands, but I also do not want to bugger up my front drive train, wheels, bearings, axle, etc..

I completely agree!

Where most of us are looking for a bump in capability is at the lower end of the lifting range, ie within 48" or so off the ground. I like you, become uncomfortable lifting a full bucket of heavy material to the maximum extended height. Lifting a good deal of weight 6 or 7 feet in the air changes the center of gravity greatly which can result in flipping the machine on its side risking damage to it and the operator...

 

[Artisan]

If you make a change please advise exactly what you did.
I would suggest that a knowledgeable operator would have
no problems. I would suggest bumping up the cylinder size
alone to start and wee what you think. I would like a Model Number
for said cylinder if you have it nailed down.

 

[Nightforce]

If you make a change please advise exactly what you did.
I would suggest that a knowledgeable operator would have
no problems. I would suggest bumping up the cylinder size
alone to start and wee what you think. I would like a Model Number
for said cylinder if you have it nailed down.

Changing cylinders should be pretty straight forward but occasionally one must become creative in order to make them fit properly. Most cross tube cylinders are designed using industry standards. Kubota makes it more difficult by using a very small diameter cylinder and lengthening one end making it fit into their design.

The hydraulic cylinder I've selected from Bailey Hydraulics.

SKU: 207385

Bore: 2.0
Stroke: 12
Rod Dia.: 1.125
Pin Dia.: 1.0

The photo below illustrates the front cylinder mount. The inside flange dimension is 2" and the distance from the pivot point center to the flange edge is 1". In order to overcome this we must remove the factory end then fabricate a new one, weld it in place which will allow the new hydraulic cylinder to fit.



Cylinder with new mount in place.



Assembly Drawing



New End Drawing



Since the cylinder ends are machined for a 1.0 diameter pin, you'll also need to buy a bushing to adapt it to for the 3/4 pin..

Also, the beauty of this approach does not affect the pump output or any other part of the hydraulic system..

 

[Artisan]

Ah HA! Another CAD man! I love AutoCAD 2D myself.
But....why not just cut both OE ends off the OE cylinder
and weld on to the new cylinder?

 

[Artisan]

Wait, ok the rear pin is 3/4" as you said, OK a simple bushing
at the rear will suffice.

Cham"b"er or Cham"f"er ?

It would save a lot of machining time and money if the chamfered
edges were just tagged w/ a belt sander yes?

Just this one change, w/o playing with pressures will more
than double the lifting power correct?

 

[Nightforce]

Ah HA! Another CAD man! I love AutoCAD 2D myself.
But....why not just cut both OE ends off the OE cylinder
and weld on to the new cylinder?

Artisan,

The original cylinder incorporates what looks like an extension which doubles as a pivot mount. I would normally say absolutely but in this case you'd ruin the original cylinder which could come in handy.

It's certainly an option and if machining resources are available it's something which could easily be accomplished..