| Valve function | Manual pedal-operated directional control valve | Uses foot movement to shift a spool and control hydraulic flow to an actuator. | Choose a guarded or shrouded pedal where accidental operation could create a hazard. |
| Common spool configurations | 3/2, 4/2, and 4/3 directional configurations | The first number indicates ports; the second indicates spool positions. | A 4/3 valve may provide neutral, actuator-extend, and actuator-retract positions. Check the exact center condition. |
| Nominal port size | G1/4, G3/8, G1/2, or equivalent SAE port options | Port size affects connection compatibility and practical flow capacity. | Do not select solely by thread size; compare rated flow, pressure drop, sealing method, and hose requirements. |
| Rated working pressure | 250–315 bar typical product class | The maximum continuous pressure permitted by the specific valve design and documentation. | The complete circuit must be rated for the highest possible pressure, including pressure spikes. |
| Pressure range to verify | Working, peak, and proof-test pressure | Working pressure is continuous service; peak pressure is short-duration capability; proof pressure is a test value. | Never use proof or peak pressure as the normal operating pressure unless the technical documentation explicitly allows it. |
| Typical flow capacity | Approximately 20–80 L/min, depending on bore, spool, and pressure drop | Flow capacity determines actuator speed and energy loss through the valve. | Use the manufacturer’s flow-versus-pressure-drop curve rather than port size alone. |
| Actuation method | Direct mechanical pedal or pedal with lever linkage | Mechanical input shifts the spool without electrical power. | Evaluate pedal travel, operating force, return mechanism, mounting rigidity, and operator ergonomics. |
| Return and detent options | Spring return, maintained position, or detented position | Defines whether the spool returns automatically or remains in the selected position. | For safety-critical motion, a spring-return or monitored neutral arrangement may be preferable, subject to risk assessment. |
| Hydraulic fluid | Mineral-based hydraulic oil commonly specified around ISO VG 32–68 | Fluid viscosity and cleanliness influence leakage, wear, response, and service life. | Confirm seal compatibility before using water-glycol, fire-resistant, biodegradable, or other specialty fluids. |
| Operating temperature | Common design range: approximately −20°C to +80°C | Temperature limits apply to the valve, seals, fluid, and surrounding environment. | Actual limits vary by seal material and fluid. Verify cold-start viscosity and maximum fluid temperature. |
| Mounting orientation | Panel, base, or manifold mounting | Mounting style affects installation space, service access, and mechanical alignment. | Provide positive mechanical support and prevent side loads on the valve body or pedal linkage. |
| ISO 4413 relevance | Hydraulic-system safety principles and general rules | ISO 4413 addresses safe design, installation, operation, maintenance, and risk reduction for hydraulic systems. | Assess pressure limitation, safe isolation, stored energy, hose routing, guarding, leakage control, and emergency procedures. |
| Pressure protection | System relief valve sized for the circuit | Limits system pressure to protect the valve, actuator, hoses, and connected equipment. | A directional valve is not automatically a substitute for a correctly adjusted and accessible relief valve. |
| Neutral-position behavior | Closed center, open center, tandem center, or float-related design | The center spool land arrangement determines pump unloading, actuator holding, and downstream circuit behavior. | Match the center condition to fixed-displacement or variable-displacement pump requirements. |
| Leakage and cleanliness | Low internal leakage; filtration commonly selected near ISO 4406 cleanliness target 18/16/13 or cleaner, as required | Contamination can cause spool sticking, accelerated wear, and shortened service life. | The correct cleanliness level depends on the whole hydraulic system and component sensitivity; follow the equipment specification. |
| Supplier qualification criteria | Documented pressure, flow, cycle, leakage, material, and inspection data | Objective technical evidence helps compare equivalent valves without relying only on price. | Request dimensional drawings, performance curves, inspection records, traceability information, and replacement-seal availability. |