Unloading Valve Assembly 24V, 1 inch BSPP, 150 L/min, 350 bar

A complete, built-up unloading valve – steel body, normally open cartridge, 24V coil and LED DIN plug, ready to plumb and wire. 1″ BSPP ports, 150 L/min, 350 bar.

Use it to unload a pump to tank when the circuit is idle. It saves fuel, saves oil temperature, and takes the load off the relief valve.

Ways to buy:

• Off the shelf – one part number, ready to fit.
• Building your own? The cartridge, body and coil are all listed separately – linked below.

Pick your part

What is in the assembly

What an unloading valve does

With no power the valve is open and the pump flow goes straight back to tank at almost no pressure. Energise the coil and the path shuts, so the pump builds pressure and the circuit works. That is the safe way round: lose power, break a wire, blow a fuse, and the pump unloads instead of sitting on the relief valve turning your oil into heat.

Because it is bi-directional with a check when energised, the same assembly also works as a dump or bypass valve on a return line.

Technicians Advice

Unloading is the single cheapest efficiency fix on a machine that idles. A pump held against its relief at 200 bar is turning nearly all of that energy into heat, and on a long day that is a cooked tank of oil and a shortened pump life; an unloading valve drops it to a few bar of pressure drop and the problem disappears. Size the return line for the full pump flow – 150 L/min through an undersized tank line will build back pressure and defeat the whole point. Wire it normally open on purpose: if the control circuit fails the pump should unload, never deadhead. Give the coil a fused, clean supply and support the loom so the connector is not carrying cable weight. If the valve buzzes or gets hot, check the supply voltage under load before you blame the coil – a 24V coil fed 19V on a long run will hum and eventually cook.

Complete your setup

Normally Open Cartridge Valves2-Port Cartridge BodiesSolenoid Coils

Bulk discounts apply automatically in the cart: 5+ save 5%, 10+ save 10%, 25+ save 12.5%, 50+ save 15%.

Buying in bulk or fitting out a fleet? Call us for trade pricing.

Need help choosing? Call 1300 146 737 or email sales@mhfgc.com.au – real technicians, real answers.