Walvoil SD8/1/(XG-210)/28L/RC is a 1 Spool Hydraulic Control Valve within the SD8 sectional directional control valve family.Configured as a single-section manual hydraulic directional control valve with an XG-210 manual hand-lever kit and an RC-type main relief valve,it delivers 80 L/min nominal flow at 315 bar maximum pressure.Designed for open-center hydraulic circuits on mobile equipment,it suits single-acting or double-acting cylinder control in compact construction machinery,agricultural implements,and material handling vehicles.

　　What Is a 1 Spool Hydraulic Control Valve?

　　A 1 spool hydraulic control valve is a directional control valve containing a single spool(control element)that starts,stops,and redirects hydraulic fluid to one actuator—typically a cylinder or a unidirectional hydraulic motor.By shifting the spool via a manual lever,the operator controls the direction of oil flow,enabling extend/retract or raise/lower functions on a single implement.

　　These valves are manufactured in two structural configurations:monoblock(a single cast body)and sectional(individual sections bolted together).The SD8 series uses a sectional design,meaning the SD8/1 single-section configuration can later be expanded by adding intermediate working sections to control additional functions.A manual hydraulic directional control valve of this type serves as the primary operator interface between the pump supply and the actuator in open-center hydraulic systems.

　　Key Specifications

　　Number of Spools:1

　　Valve Series:SD8 Sectional

　　Nominal Flow Rating:80 L/min(21 US gpm)

　　Maximum Pressure:315 bar(4,600 psi)

　　Main Relief Valve Type:RC(fitted per manufacturer specification)

　　Spool Control Kit:XG-210 Manual Hand-Lever

　　Spool Type:28L(double-acting,spring-centered,A and B closed to T in neutral)

　　Spool Diameter:18 mm

　　Section Pitch:41 mm

　　Maximum Backpressure on Outlet Port T:25 bar(360 psi)

　　Internal Leakage A(B)→T:3 cm³/min atΔp=100 bar

　　Port Thread Standard:BSP(ISO 228/1),G 1/2"nominal for P,A,B,T ports

　　Fluid:Mineral-based hydraulic oil

　　Viscosity Operating Range:15 to 75 cSt(mm²/s)

　　Minimum Viscosity:12 cSt

　　Maximum Viscosity:400 cSt

　　Fluid Temperature Range(NBR Seals):-20°C to 80°C

　　Fluid Temperature Range(FPM/Viton Seals):-20°C to 100°C

　　Ambient Temperature Range:-40°C to 60°C

　　Maximum Contamination Level:19/16 per ISO 4406(NAS 1638 Class 10)

　　Valve Body Material:Cast iron

　　Handle Housing Material:Cast aluminum alloy

　　Spool Material:Steel

　　Weight(Approximate):3 to 4 kg(single-section configuration)

　　Certifications:ISO 9001 Quality Management System,CE Mark

　　Compliance:ISO 3691(forklift load descent speed limitation,per manufacturer test reports)

　　Technical Highlights

　　28L spool configuration provides closed-center neutral for leak-free load holding.The spool designation"28L"indicates a double-acting 3-position spool where both work ports A and B are blocked to tank in the neutral(center)position.This prevents cylinder drift when the operator releases the hand-lever—a critical requirement for lifting applications where load holding without creep is mandatory.

　　XG-210 hand-lever kit delivers spring-centered return for manual operation.The XG-210 control kit includes a spring-return mechanism that automatically brings the spool back to the neutral position upon lever release,providing fail-safe operation and reducing operator fatigue compared to friction-detent controls in repetitive cycling applications.

　　RC main relief valve protects downstream components from pressure spikes.Fitted on the inlet section,the RC relief valve diverts excess flow to tank when system pressure reaches the preset threshold,safeguarding the hydraulic pump,hoses,and actuator seals.A frequent question is whether the relief pressure setting is adjustable—it is.The RC type provides factory-preset pressure with field-adjustable capability within a calibrated range.

　　Sectional design allows future expansion without replacing the entire valve.Unlike monoblock single-section valves that cannot be extended,the SD8 sectional platform permits adding intermediate working sections later.A machine starting with one spool for a lift cylinder can add sections for tilt,auxiliary,or steering functions by inserting intermediate bodies between the inlet and outlet covers.

　　Heavy-duty cast iron body with ISO 4406 contamination tolerance supports mobile equipment environments.The valve body is cast iron,with steel spools rated for fluid cleanliness level 19/16 per ISO 4406.This contamination tolerance is practical for mobile machinery operating in dusty construction and agricultural environments where maintaining laboratory-grade oil cleanliness is challenging.

　　Applications

　　Single-cylinder lift control on compact equipment:Directly controls the boom or mast cylinder on mini-excavators,compact wheel loaders,and scissor lifts.The 80 L/min flow supports cylinder bore sizes up to 100 mm with extend/retract cycle times of 1.5 to 3 seconds in typical mobile equipment circuits.

　　Tipping trailer and dump body actuation:Operates the single-acting or double-acting hoist cylinder on agricultural tipping trailers and light-duty dump trucks.The 28L spring-return spool ensures the operator must hold the lever in position,preventing unintended body lowering.

　　Hydraulic log splitter and forestry equipment:Controls the main ram cylinder in mobile log splitters and small forestry processing equipment where a single spool provides sufficient function.The spring-centered design meets operator safety expectations for equipment with direct manual control.

　　Forklift mast tilt or side-shift function:Serves as a dedicated control valve for a single forklift function such as mast tilt or fork side-shift.Walvoil SD8 valves are fitted with compensator options that make fork descent speed independent of the lifted load,per ISO 3691 requirements.

　　Replacement valve for legacy mobile equipment:Directly replaces worn or failed single-spool directional control valves in older backhoe loaders,telehandlers,and agricultural tractors where the original 80 L/min-rated valve is obsolete or unsupported by the OEM.

　　Selection Guidance

　　Suitable applications:

　　Open-center hydraulic systems requiring manual control of one hydraulic actuator(cylinder or unidirectional motor)with a nominal flow demand of 50 to 80 L/min

　　Mobile equipment operating at working pressures up to 315 bar where a spring-return,double-acting spool with closed-center neutral provides load-holding capability

　　Projects where future expansion to multi-spool control is anticipated—the SD8 sectional platform supports up to 12 sections,enabling incremental system upgrades

　　Machinery operating in ambient temperatures from-40°C to 60°C using mineral-based hydraulic fluid with NBR or FPM seals

　　Not recommended for:

　　Closed-center or load-sensing hydraulic systems.The SD8 is an open-center valve.For load-sensing applications,select the DLS8 variant,which provides pressure-compensated flow control and is rated for 100 L/min nominal flow.

　　Multi-function control where two or more actuators must be operated simultaneously.A single-spool valve can only direct flow to one actuator at a time.Use a multi-section SD8 configuration(e.g.,SD8/2 or SD8/3)for simultaneous independent control of lift,tilt,and auxiliary circuits.

　　Applications requiring proportional electro-hydraulic control for precision positioning.The XG-210 manual lever is an on/off directional control with fixed flow characteristics.For proportional actuation,select a Walvoil electro-hydraulic spool control kit or consider the DPX flow-sharing series for advanced electronic integration.

　　FAQ

　　1.What is the price of the Walvoil SD8/1 single spool valve,and what does it include?

　　The SD8/1 single-section valve typically ranges from 350to700 USD per unit,depending on the specific spool configuration,relief valve setting,and order quantity.This price includes the inlet cover with RC main relief valve,one working section with 28L spool,XG-210 manual lever kit,and outlet cover.Prices fluctuate due to exchange rates,tariffs,and factory adjustments.For an accurate quotation with current pricing,contact Beijing Zhongping Technology directly.

　　2.Is the Walvoil SD8/1 available in stock or made to order?

　　The SD8 series is a current-production product line.Commonly ordered configurations with standard spool types and port thread specifications may be available from regional distributor inventory with shipment within 1 to 3 business days.Custom spool configurations or non-standard relief pressure settings are built to order with a standard manufacturer lead time of 6 to 8 weeks.

　　3.Can the SD8/1 be expanded later to add more spools and functions?

　　Yes.The SD8 sectional design allows adding intermediate working sections between the existing inlet and outlet covers by unbolting the tie rods and inserting additional sections.Expansion from a 1-spool to a 2-spool,3-spool,or up to 12-spool configuration is possible using standard SD8 intermediate sections and longer tie rods,without replacing the inlet or outlet covers.

　　4.What spool types and control options are available for the SD8 series?

　　The SD8 supports multiple spool configurations including double-acting spring-centered(28L type),double-acting with detent positions,single-acting,and float spools.Control kits range from manual hand-levers(XG-160,XG-210)to pneumatic,hydraulic pilot,electro-hydraulic solenoid,and flexible cable remote controls,allowing adaptation to different operator interface and cab layout requirements.

　　5.How do I specify or order the correct port thread type for SD8 valves?

　　SD8 valves are available with BSP(G-thread per ISO 228/1),UN-UNF(SAE per ISO 11926-1),metric(per ISO 9974-1),and NPTF(per ANSI B1.20.3)port thread options.The standard configuration for most markets uses BSP G 1/2"for P,A,B,and T ports.Confirm the thread standard required for your existing hose fittings and adapters when placing the order to avoid mismatched connections.

　　6.What is the delivery time for a Walvoil SD8/1 configured with the XG-210 lever?

　　Standard manufacturer lead time is 6 to 8 weeks for non-stock configurations.Beijing Zhongping Technology can expedite delivery for urgent requirements by sourcing from regional distribution centers with pre-configured inventory of popular SD8 variants,reducing lead time to 2 to 3 weeks depending on configuration availability.

　　7.What payment terms are available when purchasing Walvoil hydraulic valves?

　　We accept bank wire transfer(T/T),irrevocable letter of credit(L/C at sight),and major corporate procurement cards.For qualified business accounts with established purchasing history,Beijing Zhongping Technology offers net 30 payment terms following credit evaluation and approval.

　　8.Is the SD8 series compatible with previous Walvoil valve generations for replacement?

　　The SD8 series uses the same 41 mm pitch and 18 mm spool diameter as earlier Walvoil sectional valve series with compatible tie rod spacing.Many legacy Walvoil sectional valves can be replaced section-by-section using SD8 components.However,port thread standards and relief valve interchangeability should be verified against the specific legacy model code.Contact Beijing Zhongping Technology for a cross-reference compatibility check.

　　9.What warranty coverage is provided with the Walvoil SD8/1 valve?

　　We provide a 2-year warranty against manufacturing defects on all new Walvoil SD8 valves.Warranty coverage applies to the valve body,spool,seals,and relief valve under normal operating conditions with fluid cleanliness maintained per ISO 4406 19/16.Extended warranty options of up to 3 years are available for high-utilization fleet applications.

　　10.Can the relief valve pressure setting be adjusted after delivery,and are alternative pressure ranges available?

　　The RC main relief valve is factory-preset but allows field adjustment within its calibrated pressure range using a standard hex key.Alternative relief valve pressure settings—including 100 to 200 bar,175 to 250 bar,or other ranges—can be specified at order time.If your application requires a different cracking pressure than the standard preset,specify the desired range when requesting a quotation.