moparforum
New member
With DOUBLE ACTING CYLINDERS....THERE IS no RETRACTRACTED POSITION...Just as much fluid is in the RETRACTED portion as in the unretratcted. To get all the fluid out you would need to disconnect them and drain them out....
changing hydraulic fluid
- Thread starter psuedofarmer
- Start date
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depratt_equip
Platinum Member
hrmm, dipstick always shows LESS fluid when raised and FULLER when the bucket is on the ground.
moparforum
New member
It should NOT show a significant difference with a properly sealed double acting cylinder system. There is always some "bleed down" but you have just as much fluid on the one side of the piston as you do on the other...See PIC.
depratt_equip
Platinum Member
Maybe so, but the truth of the matter is that you will drain out more fluid with the cylinders retracted, which is why mfg's suggest doing this. I have had the fluid level at the full mark, raised the loader, seen the level drop a significant amount, and lowered the loader to see fluid level go back up to the full back. This has been on many tractors not just Kioti. The dipstick does not lie.
BigDogues
Gold Member
moparforum, I think that you may be forgeting about the volume occupied by the cylinder rods. This can add up to a significant amount. /forums/images/graemlins/smile.gif
With DOUBLE ACTING CYLINDERS....THERE IS no RETRACTRACTED POSITION...Just as much fluid is in the RETRACTED portion as in the unretratcted. To get all the fluid out you would need to disconnect them and drain them out....
I beg to differ with this statement
When a double acting cylinder is retracted the rod is INSIDE the cylinder. The rod displaces a volume equal to 3.1416 X 1/2 the diameter of the rod squared. an example would be....a cylinder with a bore of 3 inches and a stroke of 24 inches with a rod diameter of 1.5". The displacement of the cylinder volume with the rod extended is equal to the area of the bore (3" X pi ) which is 9.425 sq.in. This area X the length of the stroke (24) is equal to 226.2 cu.in.
In my example, the volume of space taken up by the rod INSIDE the cylinder is equal to rod diameter (1.5") X pi X length of stroke....1.5 X 3.1416 X 24 = 113.2 cu.in.
Therefore the cylinder displaces 113 cu.in less volume with the rod retracted inside the cylinder than when it is extended outside the cylinder. the fluid displaced by the rod when it is inside the cylinder has to go somewhere. Hmmm, i wonder what happens to the volume of oil in the resovior under this condition...and further, I wonder what would happen to the level of fluid indicated a dipstick, bulls eye or other indicator of fluid level in a closed container vented to atmosphere?
I beg to differ with this statement
When a double acting cylinder is retracted the rod is INSIDE the cylinder. The rod displaces a volume equal to 3.1416 X 1/2 the diameter of the rod squared. an example would be....a cylinder with a bore of 3 inches and a stroke of 24 inches with a rod diameter of 1.5". The displacement of the cylinder volume with the rod extended is equal to the area of the bore (3" X pi ) which is 9.425 sq.in. This area X the length of the stroke (24) is equal to 226.2 cu.in.
In my example, the volume of space taken up by the rod INSIDE the cylinder is equal to rod diameter (1.5") X pi X length of stroke....1.5 X 3.1416 X 24 = 113.2 cu.in.
Therefore the cylinder displaces 113 cu.in less volume with the rod retracted inside the cylinder than when it is extended outside the cylinder. the fluid displaced by the rod when it is inside the cylinder has to go somewhere. Hmmm, i wonder what happens to the volume of oil in the resovior under this condition...and further, I wonder what would happen to the level of fluid indicated a dipstick, bulls eye or other indicator of fluid level in a closed container vented to atmosphere?
Oops, just double checked my math...ERROR! I forgot to square the radius and instead used the diameters in my calculations
The volume of the rod is area X length...(Pi X radius squared X length) or 3.1416 X .75 X .75 X 24. = 42.4 cubic inches. NOT 113 cubic inches as in my previous post. Also the volume of the cylinder with the rod extended is 169.65 cu. in.This is still a significant change in displacement (25%) that will affect the level of fluid indicated in the tank.
IMO, if a person is dead set on removing all the fluid when draining a closed system with double acting cylinders then she would disconnect the hose from the rod end of the cylinders while the rods were retracted and then SLOWLY extend the rods to expell the fluid from the rod side of the piston. Then (making sure the hose is full of fresh fluid to the very end) reconnect it to the cylinder and retract the rod back inside. Unless the system was substantially contaminated I am not sure this is worth the effort. The filter can easily contain the small amount of contaminants left in the oil from rod ends that were not drained assuming there are minimal amounts of contamination in the fluid.
Having said all that, I will do this procedure on my 50 hour initial change of hydraulic fluid since this was the break in period and more likely to have metal and other contamination in the fluid than the following fluid changes should have..
The volume of the rod is area X length...(Pi X radius squared X length) or 3.1416 X .75 X .75 X 24. = 42.4 cubic inches. NOT 113 cubic inches as in my previous post. Also the volume of the cylinder with the rod extended is 169.65 cu. in.This is still a significant change in displacement (25%) that will affect the level of fluid indicated in the tank.
IMO, if a person is dead set on removing all the fluid when draining a closed system with double acting cylinders then she would disconnect the hose from the rod end of the cylinders while the rods were retracted and then SLOWLY extend the rods to expell the fluid from the rod side of the piston. Then (making sure the hose is full of fresh fluid to the very end) reconnect it to the cylinder and retract the rod back inside. Unless the system was substantially contaminated I am not sure this is worth the effort. The filter can easily contain the small amount of contaminants left in the oil from rod ends that were not drained assuming there are minimal amounts of contamination in the fluid.
Having said all that, I will do this procedure on my 50 hour initial change of hydraulic fluid since this was the break in period and more likely to have metal and other contamination in the fluid than the following fluid changes should have..
OP
psuedofarmer
Gold Member
my observations on changing the hydraulic fluid:
1) when draining the fluid, you'll need (2) 5 gallon buckets AND a spare drain pan. the manual suggests that that system holds 10 gallons. that's correct.
2) there are 2 drain plugs on the DK55. if you've got a BH mount installed, you'll need to remove that to gain access to the plug nearest the engine.
3) i attempted to remove plugs simultaneously (i loosened them until they were ready to drop fluid, then pulled them both at nearly the same time); the reservoir nearest the engine held 5.5 gallons.. plan accordingly!
4) replaced filter and filled system with 9 gallons; started engine, let idle for 5 minutes. let sit for 5 minutes. checked fluid - the dip stick indicated that the fluid was just below the line, so i added the extra gallon.
- this is where i made my mistake -
5) attach BH. check hydraulic fluid. TOO HIGH! back under the tractor, draining ~ 1.5 gallons.
moral of the story:
a BH holds ~ 1.5 (have a rhino BH) gallons of hydraulic fluid. make sure you factor that in when adjusting the amount of fluid. the front reservoir seems to hold slightly more than 5 gallons. and the most important: if you're doing this for the first time, make sure you have lots of rags - and more importantly - a hose to remove the hydraulic fluid from your hair.
pf
1) when draining the fluid, you'll need (2) 5 gallon buckets AND a spare drain pan. the manual suggests that that system holds 10 gallons. that's correct.
2) there are 2 drain plugs on the DK55. if you've got a BH mount installed, you'll need to remove that to gain access to the plug nearest the engine.
3) i attempted to remove plugs simultaneously (i loosened them until they were ready to drop fluid, then pulled them both at nearly the same time); the reservoir nearest the engine held 5.5 gallons.. plan accordingly!
4) replaced filter and filled system with 9 gallons; started engine, let idle for 5 minutes. let sit for 5 minutes. checked fluid - the dip stick indicated that the fluid was just below the line, so i added the extra gallon.
- this is where i made my mistake -
5) attach BH. check hydraulic fluid. TOO HIGH! back under the tractor, draining ~ 1.5 gallons.
moral of the story:
a BH holds ~ 1.5 (have a rhino BH) gallons of hydraulic fluid. make sure you factor that in when adjusting the amount of fluid. the front reservoir seems to hold slightly more than 5 gallons. and the most important: if you're doing this for the first time, make sure you have lots of rags - and more importantly - a hose to remove the hydraulic fluid from your hair.
pf
depratt_equip
Platinum Member
Just a side note: If you remove 1 plug you will still remove all the fluid from the transmission. The different cases in the tractor all flow together.
Did you work all the cylinders when you attahced the BH to remove any air that might be in them?
Did you work all the cylinders when you attahced the BH to remove any air that might be in them?
OP
psuedofarmer
Gold Member
<font color="blue">If you remove 1 plug you will still remove all the fluid from the transmission. The different cases in the tractor all flow together. </font>
funny you should mention this.. i now recall someone making this statement (why i earth i neglected to remember it is beyond me!).
being the rocket scientist i am, i operated ONLY the bucket cylinders, and not the stabilizer cylinders once i attached it. the BH is operating normally with the hydro fluid in the specified range.
my learning curve is finally bending in my favor!
thx again!
pf
funny you should mention this.. i now recall someone making this statement (why i earth i neglected to remember it is beyond me!).
being the rocket scientist i am, i operated ONLY the bucket cylinders, and not the stabilizer cylinders once i attached it. the BH is operating normally with the hydro fluid in the specified range.
my learning curve is finally bending in my favor!
thx again!
pf
