BX25 transmission circuit pressure

[Tachdriver]

Anyone know what the discharge pressure is from the transmission pump thru the oil filter ? I am trying to size a pressure gauge for a remote oil filter system. Someone may have a shop manual that will tell you this. I don't want to know the hydraulic line pressure, just the pressure seen to the oil filter and back.


Later

 

[Tachdriver]

Somebody get out that shop manual

There must be two pumps inside the casing - one for hydraulics and one for transmission lube ??


Later

 

[keyman1808]

I have a BX24 but my WSM is at home and I'm at work. I try to remember to look tonight.

 

[Tachdriver]

Keyman - much appreciated. I am interested in the lubrication circuit involving the oil filter and such. What is the pressure I am expecting to see there.



thank you !

later

 

[CT Jay]

Tach....

Page 1-S14 in my BX25 WSM......(entire manual dated August 2008)

At the bottom of this page they print "W10756890", which I assume to be a reference for Kubota to that page for their update and other purposes.

Engine Oil Pressure....

"At idle speed - Factory spec" - 7 psi
"At rated speed - Factory spec" - 28 to 64 psi
"At rated speed - Allowable limit" - 21 psi

As long as I have the page open, here's more info that they provide, in case you need it....

"Tightening torque - Oil pressure switch" - 10.8 to 14.5 ft.lbs

"Relief valve spring"....(in reference to "free length of spring").
Factory spec - 1.26 in. (32mm)
Allowable limit - 1.10 in (28mm)
"Tightening torque - Joint" - 29.0 to 36.3 ft-lbs

At the top of this "Engine Oil Pressure" page, they provide the following sentence....
"Remove the engine oil pressure switch, and set an oil pressure tester. (Code No. : 07916-32032)".
I don't know what the "Code" refers to, but since it's on the page at the top, I'm mentioning it in case it's useful to you.

If you'd like me to fax or scan/email this page to you, reply to me with your fax/email. They have two b/w photos and a diagram on this page, with some kind of code numbers imprinted in the corner of each photo and the diagram....again presumably for their own internal update purposes.

Finally, I gave you the specs they print in units of psi, ft-lbs, in., etc....but they also give equivalents in units of kPa, kgf/cm2, N-m, kgf-m, etc.....let me know if you need those numbers......I don't imagine you do, but they're there just in case.

J

 

[CT Jay]

Tach.....hold on before you use the info on my previous post....that data is for engine oil.....but you want transmission info......

Duh.....my dumb....

Stand by and I'll look that up for you....

J

 

[CT Jay]

OK, here's the Hydraulic specs....(there are no specs in the Hydraulic System section whatsoever that specifically reference pressure in/out of the filter itself)


....on page entitled "Hydraulic System - Servicing Specifications" (page 5-S2) and also on the page entitled "Checking and Adjusting Relief Valve" (page 5-S4)

"Relief Valve - Setting Pressure" - 1778 to 1849 psi (no entry present in "allowable limit" column)
Engine Speed: Maximum
Oil temp: 113 to 131 F (45 to 55 C)



....on Page entitled "Hydraulic System - Pump and Priority Valve" (page 5-S5)

"Power steering oil flow - factory spec" - above 8.0L/min. (2.1 U.S. gals/min)
Conditions...
Engine speed: 1500 min rpm
Oil temp 113 to 131 F (45 to 55 C)

"Hydraulic pump delivery at no pressure - factory spec" - Above 24.9 L/min. (6.6 U.S. gals/min.
Conditions...
Engine speed: Maximum
Oil temp 113 to 131 F (45 to 55C)


There's also a numbered list of instructions for proper procedure to measure flow, etc.....i.e., what to do, where to connect/disconnect, etc etc.....I'm guessing you don't need that info, but if you do I'll fax or scan/email the page to you because it's a lot to type out here......there are 3 photos on the page as well.

J

 

[CT Jay]

One more thing... (you probably don't need this, but just to be complete....)

...."Power Steering Relief Valve" (page 4-S2)
Operating pressure - 1209 to 1280 psi (no data in "allowable limit" column)

J

 

[CT Jay]

Perhaps I have a reading disability......I read your posts again, and I see that I've AGAIN given you info that isn't what you asked for.....so, one more time....


Specifically, for hydrostatic transmission.....in the major section entitled "Transaxle".....

Charge Relief Valve...Setting Pressure....79.8 to 108.8 psi.....(oil temp at 122F)

High Pressure Relief Valve (forward and reverse).....Setting Pressure....2775 to 3190 psi...(oil temp 122F)

PTO clutch operating pressure...factory spec.....145.0 to 188.5 psi


These are the only pressure specs listed for the hydrostatic transmission (transaxle). No specs or references to pressure in/out of oil filter are given. Under "Oil Flow" diagram page, the following printed explanation of the circuit diagram of the hydrostatic transmission, if of any value to you....

"The pump and motor are joined in a closed hydraulic loop and most of oil circulates within the main oil circuit. A little oil lubricates and oozes out from the clearance between the moving parts of the case. Then oil in the main oil circuit of the HST needs to be supplied a want.
The oil from the power steering circuit flows into the HST for charging.
The charge oil aids smooth operation of pistons for pump and motor. The charge oil passes through the oil filter cartridge to charge relief valve port. The rest of oil passes through the charge relief valve into the HST housing., and overflow oil from HST housing return to the transmission case."

This is followed by pages illustrating oil flow for Neutral, Forward, Reverse, Relief (reverse).

J

 

[Tachdriver]

NOW you hit it on the head CT Jay - 79.8 to 108.8 psi. That is exactly what I am seeing after installing a pressuge gauge. The pump discharge to the oil filter on the TRANSMISSION front is showing 105psig at 2000rpm at 100F oil temperature.

So this helps a LOT. Now onward with my "master" project, :thumbsup:


Later