Any other Kubota's power steering "hit a stop" for a moment?

[leonz]

The issue is the mass of the loader and tractor when moving as the loader and the loaded bucket are referred to as an "over center load" which will momentarily affect the the steering control of the tractor because the external force created by the load creates a very high loading force on the drive train and steering at the same time as there are ni cushin valves in the stering circuit-if you are worried simply reduce the size of the bucket loads you are carrying or scooping.

Driving fast with mower can do the same kind of voodoo with the tractor braking putting more wieght on the axle and steering cyclinder and pins.

 

[arsenix2001]

The issue is the mass of the loader and tractor when moving as the loader and the loaded bucket are referred to as an "over center load" which will momentarily affect the the steering control of the tractor because the external force created by the load creates a very high loading force on the drive train and steering at the same time as there are ni cushin valves in the stering circuit-if you are worried simply reduce the size of the bucket loads you are carrying or scooping.

Driving fast with mower can do the same kind of voodoo with the tractor braking putting more wieght on the axle and steering cyclinder and pins.

Dont think thats the issue here, happening with no load, i had pallet forks empty and it happened. I notice mine does it off a start while turning.

 

[Grandad4]

Still no response from my dealer yet; Still prob due to holidays.

I did notice today, though, that the steering "bump" seemed to occur most often while turning while going forward just after having been backing up. Like the transition from backing to forward is a little too much for the tractor's hydraulics. I foresee this getting to where I can actually make it happen.

In your original post, you commented that you keep your rpm's low, but you just said less than full pto rpm, which could be anything under, what, 2600. Well, how low do you you mean? 900 rpm? 1500? 2000? The closer to idle you are, the less flow in the hydraulics. It varies according the model of tractor, but you typicially need to get somewhere around 1/2 throttle for adequate flow. I think you have an Lxx40 with the new computerized HST's, so maybe the computer is taking care of this for you, but the underlying issue is the same.

On my older L without the computer, it wants to be 1800 or more when there is weight in the FEL or it's digging and lifting. If you have it up in that rpm range and it still happens, either there is something wrong or you're doing some pretty agressive driving . If it's snagging at 1200 to 1500 or less, I think you need to wind it up more.

 

[leonz]

Its a dead spot in the gearing where
the gear backlash may be slightly
sticking-happpens with steering motors
and rack and pinions or tight turns
from a stop.

 

[beppington]

The issue is the mass of the loader and tractor when moving as the loader and the loaded bucket are referred to as an "over center load" which will momentarily affect the the steering control of the tractor because the external force created by the load creates a very high loading force on the drive train and steering at the same time as there are ni cushin valves in the stering circuit-if you are worried simply reduce the size of the bucket loads you are carrying or scooping.

In my L3940's 130 hours I've pushed some dirt & lots of trees, but haven't really used the bucket for scooping dirt or carrying any heavy loads. So, a loaded / heavy bucket couldn't be the cause on mine.

In your original post, you commented that you keep your rpm's low, but you just said less than full pto rpm, which could be anything under, what, 2600. Well, how low do you you mean? 900 rpm? 1500? 2000?

1500 for everything non-PTO (except road travel), & 2000-2100 for bush hogging (my only PTO implement (OK it's my dad's)) & road travel. And I get the steering "bump" at both of these RPM settings ... except not at road travel speeds (12-13 mph), not that I'm doing much turning at 13 mph!

 

[beppington]

Dont think thats the issue here, happening with no load

x2 (no loaded bucket anyway)

I notice mine does it off a start while turning.

I "think" this is when mine does it most often, too. Like when I'm bush hogging in the woods amongst larger trees, where I need to back in & out of tight spaces while doing a lot of quick steering.

 

[zzvyb6]

It's officially called 'pump blockage' in the industry. We sometimes casually refer to it as 'morning sickness'. Because of oil flow problems, the volume rate of oil required by the power piston in the steering gear when you turn is greater than the flow rate supplied at the gear, hence it gets stalled until the oil catches up. Several things can cause it: plugged filter, water contamination in oil, crimped suply or return line, pressure relief blow off, etc. Usually happens when the system is cold at first startup. Usually goes away when the oil, pump and gear warm up.

Low oil, filter and fluid change would be my first suggestions, then look for a kinked supply or return line or collapsed hose. A hydraulic pressure gauge at the pump outlet shows all. Either there's pressure and the blockage is downstream or there's low pressure. In a power steering gear, oil has to leave the gear quickly at the same rate as it fills. If the exit lines are blocked. the gear will seem blocked.

This happens in frequently happens in FWD cars with R&P steering in cold weather. Goes away as soon as it warms up. Was common in 1980's GM FWD cars for which I changed hundreds. A bad seal in the steering valve bled off supply pressure. As soon as it warmed up, the valve body expanded and the seal got better.

 

[Bswope]

I have had the EXACT same thing happen on my L3540 which is practically new. Its like a microsecond jam in the steering, usually happened when i was using auto throttle and steering as i hit the hst pedal... yet i can never make it happen on purpose.... may consider calling the dealer if it gets irritating as I only have 25 hrs so far.

Not to get off subject but would you happen to have any pics of your 3540? Im gonna be buying one in the near future and would love some pics and feed back on the 3540.

Thanks and sorry for the derail

 

[beppington]

Not to get off subject but would you happen to have any pics of your 3540? Im gonna be buying one in the near future and would love some pics and feed back on the 3540.

Should look darn close to my 3940: See here

 

[kuboman]

Really this is a common symptom of these tractors. The hydraulic system is just a little undersized. I would not get concerned unless it does it to the point of being dangerous. All my machines have done it since new. Most always at lower rpm (less than 1500)