BX25 FEL CYLINDER ENHANCEMENT

IslandTractor · Jul 15, 2016

I'd say you need a bigger tractor.

Stock lift on the 25 is about 600lbs as I recall. Doubling that to 1200 puts you way over what those front axles were designed for. How do you think you can lift 1200lbs without breaking your axles? Actually you probably will simply lift up the rear of the machine as the BH only weighs about 600lbs so unless you get crazy with ballast all your going to accomplish is to screw up a perfectly nice BX and turn it into a rocking horse. It's your tractor though. Have fun and post photos.

Nightforce · Jul 15, 2016

There's a lot of truth in everyone's statements.

Machines are designed to meet specific parameters set forth early in it's design. Does anyone know the actual loads the BX25 can actually endure over time? I know I don't and I don't pretend to. While I did think about the front axle I may be guilty of not giving it the consideration it's due.

Specs.

Counterweight is another important consideration. As the FEL load increases the front axle / wheels become the fulcrum or pivot point. To counteract this load additional load must be added to the rear to prevent lifting the rear wheels off the ground. According to the data above, the BX25D sporting the front end loader and backhoe weigh in at 2,700 pounds.

Having the backhoe attachment in place clearly adds a lot of ballast to the equation. According to Kubota, the backhoe attachment adds an extra 617 pounds

One could contact Kubota and pose the question whether or not the force of a 2" cylinder compared to that of a 1.5" cylinder is a lethal combination.....but I'm almost certain they'd plead the 5th due to liability issues.

Caution is always advisable anytime we uses these machines whether completely original or slightly modified.

Before I move forward I'll see if I can gather more information especially regarding the front axle...

Nightforce · Jul 15, 2016

Not to muddy the water but here's a few specs on the loader itself.

IslandTractor · Jul 15, 2016

Nightforce said:
Not to muddy the water but here's a few specs on the loader itself.

That's useful.

FWIW, from my perspective the BX25 and earlier siblings were never designed to compete or do the same work as larger CUTs. They are mostly used around the house or smaller properties doing work that a man with a shovel and wheelbarrow could do. The BX works about as well as three or four men with shovels and wheel barrows. Men with wheel barrows cannot lift and move half ton rounds of hay and neither can a BX. A few men with shovels and wheelbarrows cannot move a half ton boulder. Neither can a BX. A few men with shovel and wheelbarrows could dig out a moderate size stump and so can a BX.

If you need to move something that weighs more than 500lbs, get a bigger tractor. The BX is perfect as is.

Nightforce · Aug 17, 2016

Like everything in life, all good things take time!

Modifying the set of cylinders I described on page 2 requires an adapter in order for them to fit in the stock loader arms. I machined the blocks below and when I get a few bucks put aside I'll order the cylinders and modify them by removing the standard mount then welding on these..

Nothing fancy, just some low carbon steel milled, drilled, and tapped..

Nightforce · Aug 24, 2016

Personally, I do not like running my rpm's in the 3,000 range and much prefer them in the 2,200 to 2,500 rpm range. Having a slightly larger, (2.0" diameter) hydraulic cylinder will help me at the lower end of the pressure curve.

BX25D

As you can see by the information below, there is a significant difference in pump output pressure at an idle vs the working rpm range. Do the math and see how this difference equates to force and lifting ability.

Hydraulic Pump Pressure

1500rpm

3000rpm

Chart

Nightforce · Sep 24, 2016

Just to keep the thread alive, I decided to add an intermediate step the improving the performance is the front end loader.

I bought some shims and adjusted the pump pressure to the front end loader. As we've all seen, Kubota sets this at about 1775psi. With the appropriate shims I was able to boost the output pressure to 2000psi at 2500rpm.

Before I make any changes to the cylinders, I felt this was a great intermediate step. I'll gauge it's performance throughout the fall and winter to see just how much of a difference adding 225 psi really makes...

More to come I'm sure!

Nightforce · Sep 30, 2016

I found a Kubota add for the BX series and they state the working capacity of the front axle is 1800 pounds.

Tomtint · Sep 30, 2016

Nightforce said:
I found a Kubota add for the BX series and they state the working capacity of the front axle is 1800 pounds.

One would assume that's Gross capacity. ..1/2 the weight of the tractor and attachments as well as a 600 lb cargo in the bucket at full lift.

IslandTractor · Sep 30, 2016

Tomtint said:
One would assume that's Gross capacity. ..1/2 the weight of the tractor and attachments as well as a 600 lb cargo in the bucket at full lift.

Agree. There is also the question of static versus dynamic load. Lifting is one thing, traveling on a bumpy path with a heavy weight also needs to be part of the equation.

Kubota is pretty conservative in how they engineer their tractors but they also make "compromises" to keep the total weight down. The BX class in particular is primarily designed and optimized for lawn care rather than grunt work in the field or ground engaging activities. I'd imagine the consistent undersizing of front end loaders through the BX, B and even L lineup (compared to for example Kioti and Mahindra) is related to their efforts to keep weight down and their use of smaller front axles. Compare the size of the BX axle (and tractor weight) to a similar horsepower Kioti CK2510 or 2610. Notably different.

The BX is a great tractor but it isn't ever going to compete on loader power. I'd leave it just like Kubota designed it knowing that it probably could have a stronger loader but that as is it is near perfect. If you need a bigger loader get a bigger tractor.