B26 loader (TL500) boom cylinders weak

handymantim · Sep 6, 2014

Has anyone replaced the 2" boom cylinders on their TL500 loader with something larger, like 2.5"? The OEM cylinders are weak. That implies the components underneath (frame, axle, etc) are the reason for the weak cylinders. But there is some possibility Kubota was trading power for speed? I wish I had factual data/info on the frame & axle weight limitations for the B26. I would prefer lifting power over speed and would like to buy larger diameter cylinders to get more power. Any Kubota engineers out there willing to chime in? Any owners out there who upgraded their boom cylinders? If so, positive or negative (i.e breakage) results?

CHDinCT · Sep 6, 2014

handymantim said:
Has anyone replaced the 2" boom cylinders on their TL500 loader with something larger, like 2.5"? The OEM cylinders are weak. That implies the components underneath (frame, axle, etc) are the reason for the weak cylinders. But there is some possibility Kubota was trading power for speed? I wish I had factual data/info on the frame & axle weight limitations for the B26. I would prefer lifting power over speed and would like to buy larger diameter cylinders to get more power. Any Kubota engineers out there willing to chime in? Any owners out there who upgraded their boom cylinders? If so, positive or negative (i.e breakage) results?

Have you checked your pressure relief valve setting? You may just need to shim the PRV with a few washers if you're max pressure is under spec (don't know what that is for your machine but someone here should know). Would be alot cheaper to up the pressure to spec or a little over vs buying two new boom cylinders.

handymantim · Sep 6, 2014

I haven't checked the Pressure Relief Valve setting. I have no idea where that is or how to check it. I'm sure I do not have the proper equipment to check it. Tractor is brand new....currently at about 11 hours so being the typical lamb/consumer, I ASSUME the pressure relief valve setting is correct. You are correct, though, I'd much rather install a couple washers than buy new cylinders. Who knows, maybe the PRV for my tractor was built on a Friday and the dude had other things on his mind.

handymantim · Sep 6, 2014

Is there a "backyard" way to check the PRV? i.e. should the loader lift the back tires off the ground or at least try? My loader doesn't even come close to trying. There is a backhoe installed and there is no ballast in the rear tires.

ultrarunner · Sep 6, 2014

I took a quick connect from the and attached it to a gauge and found my Kubota 9% below factory spec.

Adding a shim made a noticeable improvement.

CHDinCT · Sep 6, 2014

Don't know of any backyard tricks to check the pressure setting but since it's new, I'd call the dealer and ask them to come out and check it for you. All you/they need is a pressure guage hooked into one of your FEL ports to check the pressure. Something like this would do. Get a short piece of hydraulic hose and the right quick connect for your B26 and you can check your pressure.

Gauge:
3000 PSI 2.5" LF LM GAUGE
Hose:
1/4" X 12" 1/4 NPTM X 1/4 NPTM 2750 PSI HYD HOSE

Don't know what size or type of quick connect Kubota uses on a B26, but your dealer should have them or be able to order them for you.

As far as where the PRV is, it should be somewhere on your hydro-static transmission and basically is a bolt with a valve under it that is normally held closed by a spring. When your oil pressure rises to the max level for the spring, the spring will compress and open a port to let the oil flow back to the reserve tank, thereby relieving the pressure to protect your hydraulic components - hoses, valves, and pump. By adding a few very thin washers, it will increase the pressure required to open the relief valve. If you can get a parts diagram of you HST, you should be able to find where the PRV is and also, what the part numbers are for the washers you'd need. I recently checked the pressure on my BX25 and increased it from just over 1,700 psi to 1,900 psi. Spec is around 1,800 psi. Just slightly above spec but enough to notice a difference in my loader.

Hope some of this is helpful, but I'd start with your dealer since it's new. It's not unusual for Kubota's to come from the factor a little under spec for pressure. I think they like to be conservative when they set them up.

skyhook · Sep 7, 2014

The Boom lift capacity, end, @ ground (lbs): is 783lbs.

Gary Fowler · Sep 7, 2014

I can lift my B26 off the ground easily with the boom extended about half of its total distance and I know my pressure is a bit lower than max (2400). If yours wont, then the PRV pressure is too low. The PRV is under the tractor in front of the right wheel (when setting on the tractor). There is an external cover that have to be removed to access it, then it is unscrewed from the tractor to access the PRV spring. You really need to remove the tire to get to it easily. I would make the dealer up the pressure to max. Any backhoe has to be able to lift itself to operate functionally. I sometimes use my boom to lift the tractor, then swing the boom to reposition the tractor when digging. To do this, you need to raise the FEL though so it doesn't stress the FEL/backhoe frame too much.

Ken45101 · Sep 7, 2014

783# is indeed anemic. My B21 is spec'd at 926#

With those few hours, if you are unsatisfied, perhaps the dealer will take it back for something bigger. When I bought the B2710, I first tried something smaller and less expensive. After one session of mowing, I knew it was the wrong choice and went back to the dealer. They were very willing to take it back and sell me the B2710, which I've had for 15 years now.

I certainly would not start replacing the cylinders. Assuming Kubota did a good design, upping the cylinder lift will make something else the weak point and you could end up with very serious structural damage.

I do agree, at a minimum, have the dealer check the hydraulic pressure to make sure it's in spec.

Ken

handymantim · Sep 7, 2014

Thanks everyone for your input. I may have misled....it's the boom cylinders on the Front End Loader (TL500) not the boom on the backhoe. When I said, "lift the back tires off the ground" in an earlier post I was wondering if other people's front end loaders are strong enough to "fulcrum" the back tires off the ground when they attempt to lift a heavy load. Thanks.