What is a Control Valve?

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What is a Hydraulic Control Valve?

Hydraulic control valves start and stop fluid flow into hydraulic cylinders or hydraulic motors. They operate either manually or electronically (solenoid-operated). The number of cylinders or motors that a control valve can operate depends on the number of spools. The flow rates represent the maximum allowed GPM (Gallons Per Minute) that a valve can handle. A common example of a hydraulic control valve is the loader valve on a tractor.

Hydraulic control valves start and stop fluid flow into hydraulic cylinders or hydraulic motors.

Why Do I Need a Control Valve?

  • To add a new implement or function to the front or rear of machine
  • Replace old or damaged valve

What Types of Hydraulic Control Valves Do You Carry?

Electric Directional Control Valve

These Hydraulic Control Valves operate any hydraulic cylinders (“A” Spool) or hydraulic motors (“D” spool) using electronic switch boxes. These valves have Max. allowed flows of either 15 GPM or 25 GPM. In addition, they have (1) inlet port and (1) high-pressure tank port.

Solenoid Monoblock Control Valve

These Hydraulic Control Valves operate any hydraulic cylinders (“A” Spool) or hydraulic motors (“D” spool) using electronic switch boxes. These valves have Max. allowed flows of either 13 GPM21 GPM or 27 GPM. In addition, they have (1) inlet port and (1) low-pressure tank port, (1) optional power-beyond port. These valves convert for use on closed-center hydraulic systems (adapter required).

Manual Monoblock Control Valve

These Hydraulic Control Valves operate any hydraulic cylinders (“A” Spool) or hydraulic motors (“D” spool) using levers or cables. These valves have Max. allowed flows of either 11 GPM21 GPM or 31 GPM. In addition, they have (1) inlet port and (1) low-pressure tank port, (1) optional power-beyond port. These valves convert for use on closed-center hydraulic systems (adapter required).

How To Identify A Power Beyond Port on My Loader Control Valve

Typically, there are seven hoses or steel tubes connected to the loader valve. If only six hoses or tubes, there is no Power Beyond Port on your loader valve. The 1st four connect to your loader for the up, down, dump, and curl functions. The fifth line comes from your pump to feed your loader valve. The sixth line goes directly to your reservoir. When the pressure relief valve opens, fluid dumps directly to the reservoir. The seventh line connects to the “Power Beyond Port” on your loader valve to power valves beyond the loader valve.

On some loader valves, a “PB” stamped marking exists next to the power beyond port. Some loaders indicate their power beyond port with green tape or a green mark on the hose or valve. Some loader valves have a power beyond sleeve inserted in the power beyond port. This sleeve looks like a nut; however, it is 3 to 4 times longer than a normal sized nut. On some loader valves there are no clues to help determine which connection is the power beyond port. Your owner’s manual may not even indicate the location.

What is the Power Beyond Conversion Plug and Do I Need It?

The power beyond conversion plug installs into the N port of ONLY MONOBLOCKS (NOT ON OUR D03 STYLE VALVES) to add another valve downstream. For example, if you were to attach two Monoblock valves in-line together, you would need the power beyond conversion plug. If you are connecting this valve to your power beyond on your loader valve, you DO NOT need the power beyond conversion plug.

The control valve comes with a G thread (British Pipe Thread Parallel) style to fit the N port of the Monoblock valve. Please refer to the product listing to ensure you are purchasing the correct power beyond adapter, as we also carry the adapter in SAE thread. We carry the P40-PB vs P40G-PBP80-PB vs P80G-PB, and P120-PB adapter plugs.

You can also refer to our COUPLERS, THREADS, FITTINGS & ADAPTERS IDENTIFICATION GUIDE for a complete breakdown.

The power beyond conversion plug installs into the N port of Monoblocks to add another valve downstream.

What is the Closed Center Conversion Plug and Do I Need It?

The closed center conversion plug installs into the N port of ONLY MONOBLOCKS (NOT ON OUR D03 STYLE VALVES) to convert the open-center valve into a closed-center one. If your system is a closed center system, you need this plug. If you are unsure if your tractor is open-center or closed-center, please refer to your owner’s manual or Google machine specs.

The control valve comes with a G thread (British Pipe Thread Parallel) style to fit the N port of the Monoblock valve. Please refer to the product listing to ensure you are purchasing the correct power beyond adapter, as we also carry the adapter with SAE thread. We carry the P40-CC vs P40G-CCP80-CC vs P80G-CCP120-CC adapter plugs.

You can also refer to our COUPLERS, THREADS, FITTINGS & ADAPTERS IDENTIFICATION GUIDE for a complete breakdown of sizing.

The closed center conversion plug installs into the N port of Monoblocks to convert the open-center valve into a closed-center one.

How Do I Identify What Each of the Ports on the Valve Are?

Each port features a lettered marking to indicate what it is.

  • “P” Port: Pressure or inlet port. This port connects to your power beyond port on your loader valve, your power beyond hose, or directly to your pump.
  • “T” Port: Return or tank port. This port connects to your tank.
  • “A” & “B” Ports: These are your work ports that connect to your cylinders or hydraulic motor.
  • “N” Port: Used for closed center plug or attaching multiple valves in a row (power beyond plug required).

What Detent Options Are Available for Monoblock Valves?

Detents install into a valve. They allow you to either lock a handle into a “work” position (allowing fluid to flow to a work port hands free), or cause a handle to spring back into the neutral position when released.

We offer P40 valve detents that lock in all positions, lock in rear position, lock in forward position and a float detent. The float detent must be purchased with a float spool.

We also offer P80 valve detents that lock in all positions, lock in rear position, and lock in forward position.

What Spool Options Are Available for Monoblock Valves?

Spools are cylindrical components machined to slide in a close-fitting bore of a directional control valve. We carry 3 different types that operate very differently:

A Spool (Controls Double Acting Cylinders).

  • All spools are double acting with spring return to neutral position. A spool controls double acting cylinders
  • A and B ports are closed to Tank in neutral position

D Spool (Controls Hydraulic Motors)

  • All spools are double acting with spring return to neutral position. D spool controls non-load holding applications such as motors and horizontal cylinders.

K Spools (Float Spool)

  • A and B ports are closed to tank in neutral position with spring return to neutral position for operation of A and B work ports. Float spool allows fluid within a cylinder or motor to flow freely. For example: If you needed a mower to follow the contour of the land.
  • Must be purchased with float detent

Spools are cylindrical components machined to slide in a close-fitting bore of a directional control valve.

Do You Offer a Wiring Diagram of the Solenoid for Monoblock Valves?

Below is a drawing of the DIN Connector wiring. The monoblock solenoid operated valves corresponds directly to this.

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