Where to best measure hydraulic oil pressure and temperature?

   / Where to best measure hydraulic oil pressure and temperature? #1  

MaxG

New member
Joined
Feb 28, 2024
Messages
12
Location
Queensland, Australia
Tractor
DongFeng 30HP Tractor, Shandong Noute 2.5t Excavator
I wonder where to best measure hydraulic oil pressure and temperature on a 2.5t digger.
General wisdom says oil temperature is most accurate at oil return.
Where should I measure pressure?
I reckon there are different places, but pressure would only show when the particular cylinder is operated.
So for a more general measurement should I measure at the pump outlet? But then I have a dual pump.
Any hints appreciated.
 
   / Where to best measure hydraulic oil pressure and temperature? #2  
Measuring system pressure is generally AFTER first device that has pressure relief valve in system (a constant), at pump outlet is whatever pump can create as for whatever rpm pump is turning so pressure can fluctuate....

A common practice is to do pressure check at a QC for FEL.... IF your tractor/digger does not have a QC then you probably will have to tap one in at a convenient spot AFTER first systems pressure relief valve ... IF your tractor does not have oil cooler I'm not sure what difference it makes knowing oil temp....

 
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   / Where to best measure hydraulic oil pressure and temperature? #3  
I wonder where to best measure hydraulic oil pressure and temperature on a 2.5t digger.
General wisdom says oil temperature is most accurate at oil return.
Where should I measure pressure?
I reckon there are different places, but pressure would only show when the particular cylinder is operated.
So for a more general measurement should I measure at the pump outlet? But then I have a dual pump.
Any hints appreciated.
How are you going to measure hydraulic oil temperature?

I measure pressure at the input to the FEL controls. It would be better at the main pump outlet. I use theFEL control because it is more convenient. Measuring there gives pressure on loader lifts as well as some backhoe functions. ...plus a baseline pressure that is losses from the fluid circulating through the system.
 
   / Where to best measure hydraulic oil pressure and temperature? #4  
Temperature reading is usually reservoir temp after getting to operating temperature.
This is what is coming out of reservoir and back into the system.
 
   / Where to best measure hydraulic oil pressure and temperature?
  • Thread Starter
#5  
Thanks guys; will see what adaptors I need to hook into the system.
 
   / Where to best measure hydraulic oil pressure and temperature? #6  
My hydraulic temperature gauge is a Amazon thermocouple taped to the hydraulic hose and covered with a wad of insulation. The handheld readout sits in a coffee cup holder when I'm curious, but it usually lives in the toolbox. $29.00 complete.

The pressure gauge is older & permanent. Amazon sells a complete kit with extra types of adapters for under $100... but I didn't need the complexity. Mine is just an appropriately threaded T threaded directly to the control valve input, and supporting a glycerin-filled 1/8" NPT 5000 psi stainless steel 2" gauge. The T is hydraulic spec, not the plumber's type. Cost of the whole setup was uder $30.

Here is the hydraulic temperature gauge I used:

Screenshot 2024-06-24 at 7.27.55 AM.png
 
 
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