X Series Front Hitch Questions
- Thread starter awlchu
- Start date
- Views: 3238
awlchu,
Sorry on both counts.
I don't know what the spring is off from. Maybe your local JD garden dealer could help if you gave them the dimensions.
As to the pressure I could speculate if I ran the numbers maybe. I measured at the cutting edge of the front blade and you can see there is quite a mechanical adantage between there and the place the cylinder attaches. In other words, the cylinder extending force has to be much greater than the force out several inches.
Joe
Sorry on both counts.
I don't know what the spring is off from. Maybe your local JD garden dealer could help if you gave them the dimensions.
As to the pressure I could speculate if I ran the numbers maybe. I measured at the cutting edge of the front blade and you can see there is quite a mechanical adantage between there and the place the cylinder attaches. In other words, the cylinder extending force has to be much greater than the force out several inches.
Joe
Dutch445
Elite Member
So,
are you saying that you don't have any "float" at all with your scv? Or is it that the reaction of the float is too slow, and it generates more pressure than you like?
Sorry to be so vague, it's the first I've heard of it. The
Deere bulletin is rather vague also... but it sounds like you
guys have had engineers look at it.
Will the blade float up and down at all with your tractors? and,
is the spring or other modifications mostly there to reduce the weight of the blade etc.?
the bulletin mentioned some mechanical advantage of one end of they cylinder compared to the other,, which they say
caused this condition.....
/forums/images/graemlins/confused.gif
are you saying that you don't have any "float" at all with your scv? Or is it that the reaction of the float is too slow, and it generates more pressure than you like?
Sorry to be so vague, it's the first I've heard of it. The
Deere bulletin is rather vague also... but it sounds like you
guys have had engineers look at it.
Will the blade float up and down at all with your tractors? and,
is the spring or other modifications mostly there to reduce the weight of the blade etc.?
the bulletin mentioned some mechanical advantage of one end of they cylinder compared to the other,, which they say
caused this condition.....
/forums/images/graemlins/confused.gif
Joe,
Thanks,
I will need to go dive back into the shop manual but I though when the valve is in "float" both sides can dump into atmosphere (reservoir tank). A comment made by another X owner indicated the cooler may be causing enough resistance to prevent the system from reaching equilibrium within a reasonable amount of time (time? 3-5secs).
Thanks,
I will need to go dive back into the shop manual but I though when the valve is in "float" both sides can dump into atmosphere (reservoir tank). A comment made by another X owner indicated the cooler may be causing enough resistance to prevent the system from reaching equilibrium within a reasonable amount of time (time? 3-5secs).
Dutch445,
I think the mechanical advantage is the unbalanced surfaces (as Joe pointed out) in the lift cylinder. The rod is attached to one side of the internal piston thus you have less surface area on that side of the piston. The rod end of the cylinder points to the hitch, thus the down force.
Assume a 3 inch cylinder and 7/8 inch rod, the unbalance force is 6.5 lbs per 1 psi of system pressure.
So what does the trans-axle produce? 500psi, 1000 psi, more? Could we be seeing 650 lbs (@1ksi) of unbalanced force at the cylinder?
We could be seeing 2-300 lbs at the blade edge, too much! eeck - This is something not to overlook!
PS The spring is to offset the unbalance forces at the cylinder. In the extended position the spring needs to exert a force equal but opposite to the unbalance forces of the lift cylinder.
I really like Joe's design if Deere does not have a fix..... By the way Dutch445, what is Deere's solution in the bulletin?
I think the mechanical advantage is the unbalanced surfaces (as Joe pointed out) in the lift cylinder. The rod is attached to one side of the internal piston thus you have less surface area on that side of the piston. The rod end of the cylinder points to the hitch, thus the down force.
Assume a 3 inch cylinder and 7/8 inch rod, the unbalance force is 6.5 lbs per 1 psi of system pressure.
So what does the trans-axle produce? 500psi, 1000 psi, more? Could we be seeing 650 lbs (@1ksi) of unbalanced force at the cylinder?
We could be seeing 2-300 lbs at the blade edge, too much! eeck - This is something not to overlook!
PS The spring is to offset the unbalance forces at the cylinder. In the extended position the spring needs to exert a force equal but opposite to the unbalance forces of the lift cylinder.
I really like Joe's design if Deere does not have a fix..... By the way Dutch445, what is Deere's solution in the bulletin?
Dutch445
Elite Member
</font><font color="blue" class="small">( Complaint or Symptom:
Difficult to steer tractor with front attachment installed, does not seem like float position is working. Front blade does not float (follow ground contour) fast enough.
Problem or Situation:
None, tractor likely operating as designed.
May not understand how float function works.
SCV float function may not be working.
Solution:
Check float operation:
Start tractor, move SCV lever forward to raise front of tractor off ground.
Push lever fully forward into float detent.
Front of tractor should lower to ground. If it does not, may be a problem with the SCV float function.
Function can be verified by installing a pressure gauge into quick couplers. Run tractor with SCV in float and read pressure at each quick coupler. Pressures should be equal indicating that float function is operating as designed.
Understand float function:
Float does NOT mean ZERO down pressure.
Float simply means that the two ends of the lift cylinder on quick hitch are “connected together” allowing oil to flow from head to rod end.
There will always be some downward pressure due to the difference in surface area of the head and rod ends of the cylinder.
If situation is absolutely unacceptable to customer, install high flow oil cooler AM135340.
Additional Information:
Oil cooler is from 2005 model tractors (040001 — ).
)</font>
/forums/images/graemlins/confused.gif
Difficult to steer tractor with front attachment installed, does not seem like float position is working. Front blade does not float (follow ground contour) fast enough.
Problem or Situation:
None, tractor likely operating as designed.
May not understand how float function works.
SCV float function may not be working.
Solution:
Check float operation:
Start tractor, move SCV lever forward to raise front of tractor off ground.
Push lever fully forward into float detent.
Front of tractor should lower to ground. If it does not, may be a problem with the SCV float function.
Function can be verified by installing a pressure gauge into quick couplers. Run tractor with SCV in float and read pressure at each quick coupler. Pressures should be equal indicating that float function is operating as designed.
Understand float function:
Float does NOT mean ZERO down pressure.
Float simply means that the two ends of the lift cylinder on quick hitch are “connected together” allowing oil to flow from head to rod end.
There will always be some downward pressure due to the difference in surface area of the head and rod ends of the cylinder.
If situation is absolutely unacceptable to customer, install high flow oil cooler AM135340.
Additional Information:
Oil cooler is from 2005 model tractors (040001 — ).
)</font>
/forums/images/graemlins/confused.gif
Dutch445,
"If situation is absolutely unacceptable to customer, install high flow oil cooler AM135340.
Additional Information:
Oil cooler is from 2005 model tractors (040001 — )."
Hmmmmm.... That is interesting. I wonder what it means as far as system pressure or flow? I wonder if it would affect the tractors response or attachment response like my loader??
Any ideas anyone??
Joe
"If situation is absolutely unacceptable to customer, install high flow oil cooler AM135340.
Additional Information:
Oil cooler is from 2005 model tractors (040001 — )."
Hmmmmm.... That is interesting. I wonder what it means as far as system pressure or flow? I wonder if it would affect the tractors response or attachment response like my loader??
Any ideas anyone??
Joe
beenthere
Super Star Member
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- Tractor
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I was a guest/visitor at Horicon, WI when I brought this up to a round-table discussion with several Horicon engineers. I had some communication, after they said that "in float, unfortunately due to this oil cooler system used on the x series, that there was still about 200 pounds pressure on the blade".
The following is the final comment I received (early '04) from an engineer who obviously didn't want to be too bothered by the problem (that is when I fixed it myself with the new tabs).
</font><font color="blue" class="small">( We are actively working on a solution for the down pressure problem when using a front implement on the X-Series tractor. Unfortunately, we are in the test phase and don't have anything to put into production yet.
Please work with your dealer since the new components will be communicated with the dealer when they are available.
**********
Senior Engineer, X-Series Tractor
)</font>
I like the spring fix that is shown, and think that is a much better fix than mine (albeit mine works real well to float the blade). I would think the snowblower and broom users would complain the most about this down pressure. That 200 pounds along with the weight of the blower would put some serious wear and tear on the blade edge. I think most are just raising and carrying the front attachment, and not using 'float'.
There was some indication that 2005 models had some changes to this oil cooler to help alleviate some of that down pressure when in float. Never has my dealer heard of a fix for the early x models however.
The following is the final comment I received (early '04) from an engineer who obviously didn't want to be too bothered by the problem (that is when I fixed it myself with the new tabs).
</font><font color="blue" class="small">( We are actively working on a solution for the down pressure problem when using a front implement on the X-Series tractor. Unfortunately, we are in the test phase and don't have anything to put into production yet.
Please work with your dealer since the new components will be communicated with the dealer when they are available.
**********
Senior Engineer, X-Series Tractor
)</font>
I like the spring fix that is shown, and think that is a much better fix than mine (albeit mine works real well to float the blade). I would think the snowblower and broom users would complain the most about this down pressure. That 200 pounds along with the weight of the blower would put some serious wear and tear on the blade edge. I think most are just raising and carrying the front attachment, and not using 'float'.
There was some indication that 2005 models had some changes to this oil cooler to help alleviate some of that down pressure when in float. Never has my dealer heard of a fix for the early x models however.
keerym
Bronze Member
Sounds to me like the original oil cooler caused too much resistence in the hydraulic circuit. When in float, the two couplers are basically hooked together in the tractor's hydraulic circuit. This makes sense because if they both returned to tank, then one end of the cylinder would always be starved for oil as the other end compressed fluid out into the tank. By installing a higher flow oil cooler, this resistence is lessened, and the float "reaction time" is reduced. Sounds like a simple engineering error that didn't surface in testing with the blade attachment. Or, the component was switched at the time of production. Regaurdless, it sounds like Deere has recognized the problem and has fixed it on the new units. I really don't see a way around it other than the spring or the higher flow cooler.
