kubota loader cylinder threads (ride control)

[jonsstihl]

Hey guys,

looking for a little info. I'm planning a ride control mod on my LA854 loader on my kubota L4740.

I've already got the tee in NPT thread but just realized that the threads may be some kind of weird japanese version of NPT.

anyone know for sure if the loader cylinder fittings are NPT. I am planning on replacing the elbow on one side with a tee and hooking the accumulators to that.

talking about the Boom up down cylinder not the curl.

 

[wdchyd]

Japanese (and British) 1/4” and 3/8” pipe threads are 1 thread per inch off. Be wary of accidentally mixing them up, it could be a thread crash.
(1/4”-18 vs 1/4”-19….etc)

 

[rScotty]

Hey guys,

looking for a little info. I'm planning a ride control mod on my LA854 loader on my kubota L4740.

I've already got the tee in NPT thread but just realized that the threads may be some kind of weird japanese version of NPT.

anyone know for sure if the loader cylinder fittings are NPT. I am planning on replacing the elbow on one side with a tee and hooking the accumulators to that.

talking about the Boom up down cylinder not the curl.

I don't know which one, and not sure how I would determine it. The tapered thread - if tapered was used - will probably depend on where the loader was made and that can be a world away from where the tractor was made.

Our old Yanmar used BSPT for engine block and transmission fittings. The FEL was made in Canada & used NPT. OEM method of connecting the hydraulics involved a BSPT/NPT adapter in some places. All of which is pretty typical.

Whatever you find out, I hope you post it here.

Since you know enough about the difference to ask the question, you are probably already aware that there is no such thing as a, "weird japanese version of NPT".
The Japanese usually use the British Standard - BSPT. Which is argueably a better sealing threat than NPT and may be older. I'm not sure which is the original version - someone might know.

I'd start by looking at the thread shape with magnification, measuring the included thread angle, counting pitch (TPI), and some micrometer measurements.
Then I'd hand-fit some threads to see how they feel. Our local Ace Hardware has both NPT, BSPT, & adapters between the two in most sizes.

 

[Smokeydog]

I took the cylinder elbow, accumulators, valves, pressure gauge and measurements for a new line to a good hydraulic shop. British threads on pipe and o-ring sealing has been a problem before. Bench assembled at their shop. The old guy took the opportunity to school the young pups. British straight and tapered are common on robotics. This particular shop caters to that industry so they stock everything.

If I recall on the M59 the cylinder fitting was British male taper and two jic#8 to the hoses. One hose OEM and other to accumulators.

Soft ride makes a remarkable difference doing loader work and highly recommended. Had the hose from the cylinder tee to the accumulators armored with a external spring for extra protection.

 

[rScotty]

Smokey, do you know if the British male and female are both tapered or just the male? On a hydraulic fitting site I ran across a reference to a sealing protocol that used a BSTP tapered male but the female was BSPP. They seemed to think that was a standard & it for all I know it might be.

I know enough about tapered threads to make sure that I've got the proper male threads for hydraulics or fittings into the engine block. It didn't occur to me that the female British Standard thread form might be different from the male.

And I've still got to install that soft ride on mine. Looking forward to it as a winter project. I like the idea of more protection from pressure spikes in the hose.
rScotty

 

[Smokeydog]

I don’t know. British threads still throws me. That’s why I try to take what I can to the hydraulic shop experts. Just when I think I know what I’m doing I get humbled or a little humiliated.

 

[Thunder chicken]

These guys have some British thread fittings
I had them on my Quicke (ALO) loader.

ohcanadasupply.ca - Industrial Supply

- ohcanadasupply.ca

ohcanadasupply.ca

 

[jonsstihl]

Thanks for all the info, you're right the BSP thread was the weird japanese thread I was worried about.

I found a good hydraulic shop when I did my hydraulic ssqa setup. and reasonably priced too so they will be getting a visit when I get the time.

I will have to pull the elbow and compare to the NPT Tee that I have.

i believe the loaders are made in georgia, USA so I'm hoping it is NPT

 

[Smokeydog]

British thread in hydraulics is probably more common worldwide than NPT. My M5030 with Canadian built loader had some of both.

When I took the OEM elbow from the M59 FEL boom cylinder to match it had an O-ring above the obvious tapered threads. It was sealing nothing. The shop even asked what was the o-ring was for? It was not a surface sealing type of fitting. Just one of several oddities I’ve found.

I cannibalized some of the soft ride hardware to fit my application.

Modern tractors have done a better job of ergonomically isolating hydraulics from the operators in case of leaks or failures. I placed the majority of the soft ride components behind a OEM plexiglas window/shield for operator protection. Those accumulators store a lot of potential energy. Just something to consider. Bought some accumulators off eBay to use for a B26 loader soft ride system. One accumulator bulb might work for its’ size. Still pondering on how best to mount and shield.

 

[Thunder chicken]

Smokey, did you have a thread somewhere else about your gauge? I remember someone doing something to measure the weight they were lifting.
I dunno how much difference would be between any of these accumulators, but my loader only has one bottle. (~2500#capacity)

Jon, I had a hard time measuring my threads with a pitch gauge, im sure the shop is good enough to tell easily!

 

[Smokeydog]

Smokey, did you have a thread somewhere else about your gauge? I remember someone doing something to measure the weight they were lifting.
I dunno how much difference would be between any of these accumulators, but my loader only has one bottle. (~2500#capacity)

Jon, I had a hard time measuring my threads with a pitch gauge, im sure the shop is good enough to tell easily!

I tried using the gauge reading with a weight scale to measure payload. Loads picked with single point with a chain repeatable. Grapple not so much. Any lever arm difference influences the loader pressure.

What the pressure gauge did show was the dynamic pressure spikes from carrying loads were significantly reduced with the soft ride system. Simply a great option.

The hydraulic system is protected on the pump side with relief valves nominally 3000psi. But from the control valves to the cylinders no protection from external forces. So when you lift, curl and push your bucket or grapple into a load the lift pressure can about double confirmed by gauge. That’s why improper back dragging or pulling with grapple lids can damage your equipment with higher than designed operating pressures.

 

[ROUSTABOUT]

I worked at Kubota. JIC fittings.

 

[rScotty]

I worked at Kubota. JIC fittings.

Just like the zerk threads, there are so many kinds of hydraulic fittings it makes my head spin. There are a bunch of special tapered cones and compressed O rings that industry uses - sometimes - for instrumentation, too.
For identifying zerks, zoro.com sells a thread gauge that Smokeydog found and we both ordered.

I wonder if something similar is available for hydraulic fittings.

rScotty

 

[jonsstihl]

The hose fittings are JIC -* i believe but I was talking about the elbow into the female threads of the cylinder port.

I like your setup with the digital gauge. I have a cab so I wasn't thinking of shielding the accumulators and I was looking into piston instead of bladder since the accumulator for empty load will be bottomed out when loaded and I heard bottoming out bladder accumulators should be avoided. But then they are more bulky.

I may just end up getting a comfort ride setup from WR long. For the price its seems to be the most economical solution.

 

[jonsstihl]

I think it was discount hydraulic hose that had a great article for identifying different thread types

 

[Smokeydog]

I like the digital gauge except cold weather eats batteries. Need to try some lithium aaa. Does have USBc port so maybe could hardwire. Many features over a analog gauge like tare, zero, units, back lighting. It is a 10,000psi gauge. You do need a higher range gauge than what is used for hydraulic testing.

The Kubota soft ride uses two hydraulic bladder accumulators of different precharge pressures. I think dampen over a broad range of loads?

The NOS McCormick soft ride system off eBay, much like the W R Long version, has two accumulators of the same pressure. About 35hp tractor. Watched a utube of a video of WR Long installed on similar sized tractor with one accumulator, valve, hose and tee. Simple system.

The Kubota soft ride system RSCOTTY and I were also a new-old-stock off eBay for a large ag tractor for $200. I installed a 1/2” hard seat needle valve for extra orifice dampening but don’t need it. It did space up the plumbing stack to position the ball valve above the plexiglas shield.

 

[jonsstihl]

I was under the impression the WR long system had two different pressures in the bladders to dampen unloaded and loaded but I may have gotten the wrong impression when I was reading. I was definitely going to put a ball valve in the system so I can isolate it if needed.

the precharge pressures are where I think designing the system will get a little tricky. I am planning on starting by hooking up a pressure gauge and seeing what kind of pressure I have loaded and unloaded, then going from there. i read an article somewhere that had a ratio to use of precharge pressure vs system pressure.

 

[ptsg]

I was under the impression the WR long system had two different pressures in the bladders to dampen unloaded and loaded but I may have gotten the wrong impression when I was reading. I was definitely going to put a ball valve in the system so I can isolate it if needed.

the precharge pressures are where I think designing the system will get a little tricky. I am planning on starting by hooking up a pressure gauge and seeing what kind of pressure I have loaded and unloaded, then going from there. i read an article somewhere that had a ratio to use of precharge pressure vs system pressure.

Yeah, definitely add the ball valve. There are a lot of situations that you'll benefict from having the soft ride system turned off, like digging into a pile or do delicate work with the forks. With the soft ride on, the forks will all over the place.

 

[Smokeydog]

I’m sure the manufacturers use several parameters to select components for their systems. Things in common are they are trying to dampen the dynamic load forces while moving. The smallest SCUT to largest ag tractors operate at about the same pressure but have different flow, pump volume, and cylinder sizes.
Volume displacement also needs to be considered if designing your own system.

Mostly leave it valved in and works seamlessly. Carrying logs, lumber or steel on forks is smoother since terrain bumps are dampened. Carrying anything benefits. Valved out for pallet work or extended boom work. Also valve out when changing ssqa attachments helps. Would mount valve or solenoid control switch conveniently.

If buying a new tractor it would be an option to get.