3rd function

[maddog2020]

I have a JD 4720 that I want to add a grapple to. I already have a power beyond on my tractor I use to operate a backhoe. I purchased a 3rd function kit from Summit hydraulics. I was told to connect power beyond port to "P" port on valve from T port go to current power beyond inlet and take other side of PB to tank. That makes sense since you are just making a loop. What doesn't make sense is my power beyond has 1/2 hoses. The ports on the 3rd function block have 1/2 orb threads but the hole going through the block is maybe 1/4. They told me this will not restrict flow. How can going from 1/2 to 1/4 inch not restrict flow?

 

[nyone]

It's for a grapple that prob has 1/4in hoses. I bet the machine also wont out flow the 1/4in fitting either. It's really not a problem.

 

[maddog2020]

I agree its plenty for the grapple. My concern is the whole hyd loop is going through that block

 

[MtnViewRanch]

The inside of a 1/2" fitting should be just over 3/8". That 1/4" port size is going to heat up your oil. You really should get the 3rd function manifold changed, or at least modified.

Good luck.

 

[oldnslo]

What GPM flow is the implement circuit on the 4720? I suspect you have a D03 size 3rd function valve and they do have 1/4” flow path.

 

[MtnViewRanch]

What GPM flow is the implement circuit on the 4720? I suspect you have a D03 size 3rd function valve and they do have 1/4” flow path.

12 GPM for the implement pump. 17.1 GPM total.
He needs a different sub plate.

 

[oldnslo]

12 GPM for the implement pump. 17.1 GPM total.
He needs a different sub plate.

Subplate would help but ports in valve itself are still 1/4”. The tandem center spools typically have a high pressure drop with from P to T.

Big question is how often will he be operating at full throttle?

 

[MtnViewRanch]

Subplate would help but ports in valve itself are still 1/4”. The tandem center spools typically have a high pressure drop with from P to T.

Big question is how often will he be operating at full throttle?

The 4 valve ports are .300". So a bit larger than.250". A 40% increase. still a bit small, but better.
If he wants to do it right, then he needs a new valve and subplate.

 

[maddog2020]

Its a Hydro so I am almost always at full throttle. Correct me if I'm wrong but the valve would only be an issue if you are using the third function? If that's the case I'm not really too worried about restricted flow to grapple as is simply open or close. What I am concerned about is restricting flow to everything downstream from subplate. If fluid is just flowing through subplate when scv is not being used opening up holes in subplate would fix the problem? Am I correct?

 

[maddog2020]

I guess I don't understand. The subplate has 1/2 inch orb threads. Why would they make the whole in the subplate so much smaller than the whole in a 1/2 fitting?

 

[MtnViewRanch]

I guess I don't understand. The subplate has 1/2 inch orb threads. Why would they make the whole in the subplate so much smaller than the whole in a 1/2 fitting?

I have no idea why, but again, the through holes in a 1/2"- 1/2" fitting are just over 3/8".
The hole on the subplate can easily be drilled out to match those on the valve. The 4 valve ports are .300" which is too small for your tractor's implement GPM of 12 GPM.

If you don't want to be worrying about having any hydraulic issues down the road, you need a different valve and sub-plate.

Maybe they figure that the reduced length is short enough not to make a difference? If the tank volume is large enough, it will keep the fluid at a low enough temp to not make a difference.

I'm sure that a lot of people get away with what you have, but that does not make it right IMO.

Good luck with your decisions.

 

[oldnslo]

When ever the tractor is operating the flow is going into the P port and out the tank port of the valve so ALWAYS in the circuit.

Drill size in subplate depends on design. Most companies have a minimum wall thickness that they maintain between drill paths.

 

[polarred21]

Third function solenoid valves are different sizes and are sold by gpm flow rating. Obviously match the right one to your tractors gpm and should be no worries. Which valve do you have?