hydraulic level check M4950

[ifsixwasnine]

Hi all new member here New Zealand based.
My M4950(year unknown) decided to shear the driving shaft of the hydraulic pump.
Been trying to find what caused it and so far cavitation seems plausible.
Had fel on it but I took it off while working on
How do I check the hydraulic oil level?
What if the entire dipstick arrangement is not there?(140,150,160,170,180) Couldn't tell year of old rusty I'm sorry,you'll understand when you see her.
Any help is appreciated. Cheerzzz...

 

[Dave_eng]

I think your diagnosis is wrong. Cavitation causes microscopic erosion of the pump internals not shaft breakage.

It is more likely you have "dead headed" the pump. This means you had the pump discharging where there was no outlet for the fluid it was pumping nor relief valve available to prevent pressures from going too high.

The pump is a fixed displacement design. For each revolution of the pump a fixed volume of oil must exit or pressures go through the roof and forces on the pump drive also rise dramatically.

Tell us more about the hydraulics on your tractor. Is the FEL a factory one from Kubota. Other hydraulics stuff like rear remotes?

If there a hydraulic block on the tractor? Where does the loader get hydraulic pressure from?

Dave

 

[ifsixwasnine]

Hi Dave,
Thank you for reminding me that I know Jack about hydraulics hahaa.
Ummm,I'll take some photos when it stops raining.
I fiddled with 3 point link and after that fel stayed up,after it bounced going up.
To let it down I bleed Hydraulic hoses of fel rams(this shows how grand my hydraulic knowledge is).
After that all pressure disappeared.
I played with prv too I should add?

 

[ifsixwasnine]

This is why I thought cavitation.
Shocks,sounds, destruction.

The mechanism of cavitation can be described as follows: Any liquid will contain either gaseous or vaporous bubbles, which serve as the cavitation nuclei. When the pressure is reduced to a certain level, bubbles become the repository of vapor or of dissolved gases.


The immediate result of this condition is that the bubbles increase rapidly in size. Subsequently, when the bubbles enter a zone of reduced pressure, they are reduced in size as a result of condensation of the vapors that they contain.


This process of condensation takes place fairly quickly, accompanied by local hydraulic shocks, the emission of sound, the destruction of material bonds and other undesirable phenomena. It is believed that reduction in volumetric stability in most liquids is associated with the contents of various admixtures, such as solid unwetted particles and gas-vapor bubbles, particularly those on a submicroscopic level, which serve as cavitation nuclei.


A critical aspect of the cavitation wear process is surface destruction and material displacement caused by high relative motions between a surface and the exposed fluid. As a result of such motions, the local pressure of the fluid is reduced, which allows the temperature of the fluid to reach the boiling point and small vapor cavities to form.

 

[Dave_eng]

This is why I thought cavitation.
Shocks,sounds, destruction.

The mechanism of cavitation can be described as follows: Any liquid will contain either gaseous or vaporous bubbles, which serve as the cavitation nuclei. When the pressure is reduced to a certain level, bubbles become the repository of vapor or of dissolved gases.


The immediate result of this condition is that the bubbles increase rapidly in size. Subsequently, when the bubbles enter a zone of reduced pressure, they are reduced in size as a result of condensation of the vapors that they contain.


This process of condensation takes place fairly quickly, accompanied by local hydraulic shocks, the emission of sound, the destruction of material bonds and other undesirable phenomena. It is believed that reduction in volumetric stability in most liquids is associated with the contents of various admixtures, such as solid unwetted particles and gas-vapor bubbles, particularly those on a submicroscopic level, which serve as cavitation nuclei.


A critical aspect of the cavitation wear process is surface destruction and material displacement caused by high relative motions between a surface and the exposed fluid. As a result of such motions, the local pressure of the fluid is reduced, which allows the temperature of the fluid to reach the boiling point and small vapor cavities to form.

A common example of cavitation is ships propellers. The curved propeller surface, if poorly designed, can created low pressure areas at certain places on the propeller. In these low pressure areas, dissolved gases in the water suddenly expand and this pressure wave is the destructive force that breaks tiny metal particles out of the propeller.

A bit like cracking your knuckles.

Breaking of shafts is not this process.

Dave

 

[ifsixwasnine]

Here are some photos,might give you an idea about system.