NH TN75 hydraulic pump whining

   / NH TN75 hydraulic pump whining #1  

yeehaw

Bronze Member
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Jan 13, 2009
Messages
56
So after checking the hydraulic oil the other day and noticing that it appeared to be a diifferent color (level was ok) changed the oil and filter out and it is now whining pretty loud at start up...everything works, loader, 3pt...and after about 20 secs the whining noise stops. It was not doing this before and I had only noticed a whine at start up when it's really cold (it was 95 today)... And thoughts? Bout to do some googling and go back to the manual...
 
   / NH TN75 hydraulic pump whining #2  
Pumps will whine when they entrain fluid and air. It sounds like you pump is sucking some air in at start up and once it clears the air it's running quiet. Did you fill it to the proper level?
 
   / NH TN75 hydraulic pump whining #3  
It took me a few engine hours, after the hydraulic oil change, for everything to quiet down as it was. My guess is when you pull the dipstick, it is fll of little air bubbles.
 
   / NH TN75 hydraulic pump whining
  • Thread Starter
#4  
It didnt do it as bad last night - but still for a good 15 seconds or more....I was told to leave the cylinders extended and let them seep down by themselves and this would help to get rid of any possible air in the lines -- we'll see
thx
 
   / NH TN75 hydraulic pump whining #5  
The whine you hear might be cavitation caused by a suction leak or suction restriction. You din't want to hear that noise for a long time, as the bursting bubbles can erode parts of the pump.

Re-tighten all clamps on the suction hose.

You could try oil or grease on all the possible air entry points.

Other noise sources.

http://en.wikibooks.org/wiki/Acoustics/Noise_in_Hydraulic_Systems
 
Last edited:
   / NH TN75 hydraulic pump whining
  • Thread Starter
#6  
The whine you hear might be cavitation caused by a suction leak or suction restriction. You din't want to hear that noise for a long time, as the bursting bubbles can erode parts of the pump.

Re-tighten all clamps on the suction hose.


You could try oil or grease on all the possible air entry points.

Other noise sources.

Acoustics/Noise in Hydraulic Systems - Wikibooks, open books for an open world

You make one comment there about bubbles - could quality of oil cause more bubbles than others? Or is it more quality/condition of hydraulic system?
Thx
 
   / NH TN75 hydraulic pump whining #7  
I am pretty sure the density of the fluid will have something to do with the onset of bubbles.

The cavitation is caused by something breaking the vapor barrier of the fluid.

Is propeller cavitation, it is the propeller forcing itself through the water at a certain speed and depth that will cause cavitation.
 
 
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