TECHNICAL CATALOGUE

HDR

SELF-REVERSING VALVE

HDR3 350 bar 50 l/min

HDR5 320 bar 60 l/min

HDR_EN_2025_01

The HDR valves are directional control valves hydraulic

actuated, with self-reversing spool with porting pattern

compliant to ISO 4401-03 and ISO 4401-05.

These valves reverse the flow dir

ection when the flowrate

stops in A or B line (f.e., when a cylinder reaches the end

stroke). The reversing process is independent of the working

lines pressure.

These valves are supplied with a zinc-nickel plating making

them the perfect choice for mobile and environmental

FLOW RATE

MOUNTING

SURFACE

RANGE

TEMPERATURES

fluid -20 to +82 °C - 4 to +180 °F

FLUID VISCOSITY

FLUID

CONTAMINATION

ISO 4406:1999

Use mineral oil-based hydraulic fluids HL or HM type,

according to ISO 6743-4. For these fluids, use NBR seals.

For fluids HFDR type (phosphate esters) use FPM seals (code

please consult our technical department.

are not recommended.

FUNCTION

R

hydraulic actuated

self reversing spool

SEAL

N NBR (standard)

V Viton

VALVE SIZE

3 ISO 4401-03-02-0-05

CHARACTERISTIC CURVES - PRESSURE DROPS

Flow characteristic curves obtained with mineral oil with

viscosity of 36 cSt (170sus) at 50 °C (122 °F) and 24V DC

valve.

KNOB, TURNING (Code K)

4 OR 2037

90 shore A

Fastening bolts:

4 SHCS M5x30 - ISO 4762 - torque 5 Nm (A 8.8)

Threads of mounting holes: M5x10

Fastening bolts:

4 SHCS M6x40 - ISO 4762 - torque 8 Nm (A 8.8)

Threads of mounting holes: M6x10

mounting

surface with

correct operation.

Ensure that there is no air in the hydraulic circuit.

Valves are fixed by means of screws or tie rods on a flat

surface with planarity and roughness equal to or better than

those indicated in the relative symbols. If minimum values are

not observed, fluid can easily leak between the valve and

support surface.

We recommend installing in the circuit as shown in the two

examples, connecting port A to the rear chamber of the

cylinder. In this way, the valve automatically positions itself so

Use a HDR valve without the turning knob override.

The self-reversing function must be inactive when setting the

system pressure relief valve.

To do so, close the shut-off valve, start the pump, set the

pressure relief valve and stop the pump. Then, open the shut-

off valve and restart the pump.

Use a HDR valve with the turning knob override (code K) .

The turning knob override allows you to set the pressure value

of the relief valve also in circuits with no shut-off valves.

unscrewing the knob almost completely. Screw the knob set

screw until its head is flush with the knob itself.

The valve is in initial working condition when the set screw

head is flush with the knob itself and the knob is completely

tightened.

CIRCUITS WITH SHUT-OFF VALVE

CIRCUITS WITHOUT SHUT-OFF VALVE

WARNING:

Do not use the manual override during operation: if you need