SD4 SD5-1 SD8-1 Walvoil Manual Directional Valve 315 bar 45-90 L/min

Product Overview

The SD series are medium-to-high pressure monoblock/sectional manual directional control valves developed based on Italian Walvoil technology, covering multiple models including SD4, SD5-1, SD8-1, SD11-1, SD14, SD180-1, and SD25-1. These valves are widely used in construction machinery, material handling equipment, agricultural machinery, and industrial vehicles for controlling the start, stop, and direction of hydraulic actuators.

SD series valves feature monoblock or sectional construction with outstanding characteristics including compact size, high pressure resistance, high flow capacity, and reliable sealing. The valves integrate built-in main relief valves and check valves: the relief valve adjusts system working pressure to protect against overload, while the check valve prevents load slippage. The oil circuit employs a parallel circuit configuration suitable for open-center hydraulic systems. The directional spool offers multiple center functions including O, Y, P, and A to accommodate different circuit requirements. Manual control is the primary mode, with optional pneumatic, hydraulic pilot, electro-hydraulic, and other control methods available.

SD series supports 1–12 working sections depending on the specific model, offering flexible configuration for different equipment needs. As a high-cost-performance OEM replacement solution based on Walvoil technology, this valve maintains 100% mechanical and functional interchangeability with the original unit. Every valve undergoes rigorous simulation testing—including pressure cycling, thermal variation, and full-stroke endurance validation—to guarantee factory-grade performance.

Technical Specifications 

SD4 Series (Nominal Size 10 mm):

• Brand: Walvoil technology / High-quality domestic alternative

• Valve Type: Monoblock manual directional control valve

• Nominal Size: 10 mm

• Nominal Pressure: 16 MPa (160 bar)

• Max. Pressure: 31.5 MPa (315 bar)

• Nominal Flow: 45 L/min

• Max. Flow: 45 L/min

• Allowable Back Pressure: ≤1 MPa

• Operating Temperature: -20°C to +80°C

• Viscosity Range: 10–400 mm²/s

• Filtration Accuracy: ≤10 μm

• Body Material: Cast iron

• Working Sections: 1–7 sections

• Mounting Interface: G3/8″ (PAB ports)

• Control Mode: Manual, pneumatic, electro-hydraulic

SD5-1 Series (Nominal Size 12 mm):

• Brand: Walvoil technology / High-quality domestic alternative

• Valve Type: Monoblock manual directional control valve

• Nominal Size: 12 mm

• Nominal Pressure: 16 MPa (160 bar)

• Max. Pressure: 31.5 MPa (315 bar)

• Nominal Flow: 45 L/min

• Max. Flow: 45 L/min

• Allowable Back Pressure: ≤1 MPa

• Operating Temperature: -20°C to +80°C

• Viscosity Range: 10–400 mm²/s

• Filtration Accuracy: ≤10 μm

• Body Material: Cast iron

• Working Sections: 1 section (SD5/1)

• Mounting Interface: G3/8″

• Control Mode: Manual, hydraulic, electro-hydraulic, electric, pneumatic

• Circuit Type: With carry-over (SD5/1-D) or without (SD5/1-N)

SD8-1 Series (Nominal Size 16 mm):

• Brand: Walvoil technology / High-quality domestic alternative

• Valve Type: Sectional/monoblock manual directional control valve

• Nominal Size: 16 mm

• Nominal Pressure: 16 MPa (160 bar)

• Max. Pressure: 31.5–35 MPa (315–350 bar)

• Nominal Flow: 80 L/min

• Max. Flow: 90 L/min

• Allowable Back Pressure: ≤1 MPa

• Operating Temperature: -40°C to +80°C

• Viscosity Range: 12–400 mm²/s

• Filtration Accuracy: ≤10 μm

• Body Material: Cast iron (body), special steel (spool)

• Working Sections: 1–12 sections

• Mounting Interface: PAB: G1/2″, T: G3/4″

• Control Mode: Manual, hydraulic, electro-hydraulic, electric

• Center Function: O-type

SD11-1 Series (Nominal Size 18 mm):

• Brand: Walvoil technology / High-quality domestic alternative

• Valve Type: Monoblock directional control valve

• Nominal Size: 18 mm

• Nominal Pressure: 16 MPa (160 bar)

• Max. Pressure: 31.5 MPa (315 bar)

• Nominal Flow: 70–75 L/min

• Max. Flow: 70 L/min

• Allowable Back Pressure: ≤1 MPa

• Operating Temperature: -20°C to +80°C

• Viscosity Range: 10–400 mm²/s

• Filtration Accuracy: ≤10 μm

• Body Material: Cast iron

• Working Sections: 1–7 sections

• Control Mode: Manual, hydraulic, electro-hydraulic, pneumatic

• Applications: Dump trucks, feed mixers, cranes, garbage trucks

SD14 Series (Nominal Size 20 mm):

• Brand: Walvoil technology / High-quality domestic alternative

• Valve Type: Monoblock manual directional control valve

• Nominal Size: 20 mm

• Nominal Pressure: 20 MPa (200 bar)

• Max. Pressure: 25–31.5 MPa (250–315 bar)

• Nominal Flow: 120 L/min

• Max. Flow: 120 L/min

• Allowable Back Pressure: ≤1 MPa

• Operating Temperature: -40°C to +80°C

• Viscosity Range: 15–75 mm²/s

• Filtration Accuracy: ≤10 μm

• Body Material: Cast iron

• Working Sections: 1 section

• Control Mode: Manual

• Weight: Approx. 5.5 kg

SD180-1 Series (Nominal Size 20 mm, Sectional):

• Brand: Walvoil technology / High-quality domestic alternative

• Valve Type: Sectional manual/hydraulic pilot directional control valve

• Nominal Size: 20 mm

• Max. Pressure: 31.5–35 MPa (315–350 bar)

• Nominal Flow: 160 L/min

• Operating Temperature: -40°C to +80°C

• Body Material: Cast iron

• Working Sections: 1–12 sections

• Control Mode: Manual, hydraulic pilot, electric, cable control

• Features: Shockproof, anti-cavitation design

SD25-1 Series (Nominal Size 25 mm, Sectional):

• Brand: Walvoil technology / High-quality domestic alternative

• Valve Type: Sectional hydraulic pilot/electro-hydraulic directional control valve

• Nominal Size: 25 mm

• Nominal Pressure: 16 MPa (160 bar)

• Max. Pressure: 31.5 MPa (315 bar)

• Nominal Flow: 240 L/min

• Max. Flow: 240 L/min

• Allowable Back Pressure: ≤1 MPa

• Operating Temperature: -40°C to +80°C

• Viscosity Range: 12–400 mm²/s

• Filtration Accuracy: ≤10 μm

• Body Material: Cast iron

• Working Sections: 1–12 sections

• Control Mode: Manual, hydraulic pilot, electro-hydraulic, cable control

• Mounting Interface: G1″ (inlet), G1-1/4″ (outlet)

• Applications: Telescopic handlers, heavy construction machinery

Key Technical Advantages

1. Walvoil Technology Platform – Proven and Reliable Design

The SD series is developed based on the mature Walvoil technology platform, which has been market-validated for decades in global construction machinery, agricultural machinery, and material handling applications. Available in both monoblock and sectional configurations to suit different equipment requirements.

2. Flexible Monoblock/Sectional Construction – Versatile Application Adaptation

SD series offers both monoblock (1–7 sections) and sectional (1–12 sections) configurations. Monoblock construction offers compact size and fewer leak points; sectional construction offers flexibility with arbitrary section combinations. Customizable 1–12 section configurations are available per equipment requirements.

3. Integrated Relief Valve and Check Valve – High System Integration

The valve integrates a built-in main relief valve and check valve: the relief valve precisely adjusts system working pressure (customizable 80–315 bar) to protect against overload; the check valve prevents load slippage to ensure reliable actuator operation.

4. Multiple Spool Functions and Center Positions – Flexible Circuit Adaptation

Spool functions include O, Y, P, A, and more. The SD5 series additionally offers both carry-over (SD5/1-D) and non-carry-over (SD5/1-N) circuit types. Multiple configurations accommodate diverse hydraulic circuit requirements.

5. Multiple Control Options – Automation-Ready

Beyond standard manual control, SD series offers optional pneumatic, hydraulic pilot, electro-hydraulic, electric (micro-switch), and remote control kit options. This provides a convenient upgrade path from manual operation to automated control.

6. Broad Size Coverage – Versatile Flow Capacity

SD series covers a complete flow range from SD4 (45 L/min) to SD25 (240 L/min), accommodating hydraulic system requirements for various construction machinery from mini loaders to heavy telescopic handlers.

7. Drop-In Interchangeability – Minimized Downtime and Retrofit Costs

The valve strictly adheres to Walvoil’s original mounting dimensions and functional specifications. Whether for new system design or legacy system upgrades, this valve offers 100% mechanical and hydraulic interchangeability with the original Walvoil unit—eliminating the need for manifold modifications or piping changes, significantly reducing downtime and retrofit expenses.

Application Areas

• Forklift Hydraulic Systems – Directional control for mast lifting, tilting, and side-shifting functions

• Small Loaders and Skid Steer Loaders – Hydraulic control for bucket lifting, dumping, and attachment functions

• Sanitation Vehicles – Hydraulic actuator control for garbage compactors and street sweepers

• Agricultural Machinery – Hydraulic output control for tractors, combine harvesters, balers, and sprayers

• Material Handling Equipment – Telescopic handlers, stackers, aerial work platforms

• Construction Equipment – Mini excavators, wheel loaders, backhoe loaders

• Dump Trucks and Cranes – Hydraulic control for lifting and slewing mechanisms

• Mining and Drilling Equipment – Hydraulic control for drilling rigs and rock drills

• Industrial and General Hydraulics – Hydraulic power units, machine tools, metallurgical auxiliary hydraulics

Expert Maintenance Tips

1. Fluid Cleanliness Management

SD series directional valves have specific fluid cleanliness requirements. Recommended filtration accuracy is ≤10 μm. The clearance between spool and bore is extremely tight—contaminants can cause spool sticking or abnormal wear. Regularly monitor fluid contamination levels.

2. Relief Valve Pressure Setting

The valve integrates a built-in main relief valve factory-set to standard specifications. Any system pressure adjustment should be performed by qualified personnel who understand system requirements. The relief valve setting must not exceed the valve’s maximum rated pressure.

3. Manual Operation Precautions

Manual directional valves are operated via lever. Avoid excessive force or impact during operation to prevent damage to the detent mechanism or spool. Different models may have different return modes—confirm operating characteristics before use.

4. Installation and Sealing

Ensure the mounting surface is flat and smooth prior to installation. SD4 interface is G3/8″; SD8 PAB ports are G1/2″ and T port G3/4″; SD25 inlet is G1″ and outlet G1-1/4″. Verify that connection thread specifications match the piping and tighten fittings to specified torque. Take care not to damage or omit seals. The valve body surface is phosphated with 48-hour neutral salt spray corrosion resistance.

5. Temperature and Viscosity Monitoring

Recommended operating temperature range is -40°C to +80°C with working viscosity of 10–400 mm²/s. When operating outside this range, select appropriate viscosity hydraulic fluid or implement heating/cooling measures.

6. Periodic Inspection and Maintenance

Regularly verify smooth lever operation, reliable detent positioning, and absence of external leakage. If lever operation feels stuck or shifting is incomplete, inspect for spool sticking or damaged detent mechanism. For systems that have been idle for extended periods, perform thorough system circulation filtration before restart.