Pressure relief valve

[AKKAMAAN]

Cross-Over Relief Valve - 1/2" Port*-*Buyers*HCR050

A cross over work port RV need to be connected to tank if cylinder area ratio (capped area:rod side area) is other than 1:1

 

[Stonehaller]

A cross over work port RV need to be connected to tank if cylinder area ratio (capped area:rod side area) is other than 1:1

Yes that is true if you need to handle shock loads. If you just want to limit the force when closing the grapple, then the cross over has a path to tank through the return side of the control valve.

 

[cole0324]

Well so far I like the song Stonehauler is singing. Thanks guys. I guess I could always just be careful. LOL

 

[cole0324]

Got a diagram for the hookup of that valve? Please guys keep it simple.

 

[Stonehaller]

Normally a cross over relief is mounted as close to the cylinder as practical. But since you are not interested shock load reduction, you could probably mount this valve on the back of your tractor close to your auxiliary connections. This type of valve is basically inserted in series with the lines from the valve to the cylinder. Refer to the first attached image. The two lines from your tractor auxiliary ports go to the Valve A and Valve B ports and the Actuator A & B ports go to the cylinder. Before ordering a valve, you need to decide the pressure and port size you want. Valves are available in different pressure ranges.

The valve here may suit your application as it is adjustable from 1500-3000 psi.
Crossover Reliefs (Cushion Valves) - Cylinder Services

Another option is to mount a relief valve in the line that closes the grapple like AKKAMAAN proposed. With a valve like the Parker Series WJL shown in the second attached image you may be able to support with just a quick disconnect plugged into your auxiliary connection. One P port goes to the tractor auxiliary quick disconnect and the other P port goes the side of cylinder that closes the grapple. However, you will have to find a tank connection on your tractor for the T port.

The relief valve is cheaper than the cross over:
Differential Poppet Reliefs - Cylinder Services

Wow! who would have thought the Saints would try on an on side kick at the start of the 3rd? I must be nuts typing this during the Super bowl.

 

[J_J]

I am puzzled by the problem of to much force. You, the operator, are the one applying the force via the lever on the valve. If you were to install a gage in the grapple cylinder circuit, you could see how much pressure that you are applying. When you activate the grapple, can you not see, hear or have a feel about the force applied. I have a gage in my cylinder lift circuit, and I can see what the pressure is, and when not doing hard work, the pressure is very low. The pressure will be proportional to the force applied. There may be times when you need max pressure in order to hold a large rock in the bucket. In that case,the relief valve would relieve at the set pressure. They make valves with more lever control, which is proportional control, or more finite movements.

I have seen demonstrations where the operator picks up coke cans and moves them around with out crushing.

 

[AKKAMAAN]

I have seen demonstrations where the operator picks up coke cans and moves them around with out crushing.

I have seen proportional electro-hydraulic servo controlled log cranes pick up, out of a case, glass beer bottles in the neck, and distribute them to the crowds....