The HYDRAFORCE UPCV10-F41 is a screw-in, cartridge-style pilot unloading valve designed for accumulator-type hydraulic systems where a pump charges an accumulator and the valve manages the load/unload cycle. An internal check valve between ports 1 and 2 allows free flow from pump to accumulator (and system), while the pilot spool blocks flow from port 3 to port 4 until the pressure at ports 2 and 3 reaches the adjustable setpoint. At that point, the spool shifts to open port 3→4, unloading the pilot pump stage. When system pressure drops to 80% of the setpoint, the valve closes and the pump recharges the accumulator. This two-position, internally-piloted action eliminates the need for external pilot lines or separate unloading logic.

Why 80% reload ratio matters for accumulator circuit design

The fixed 80% reload ratio defines the pressure differential between the unloading setpoint and the recharge trigger. For example, with the valve set to unload at 200 bar, it will re-close and re-engage the pump at 160 bar (80% of 200). This ratio determines the usable fluid volume stored in the accumulator between the maximum and minimum system pressures — a narrower ratio (closer to 100%) would cycle the pump more frequently, while a wider ratio stores more energy but requires a larger accumulator. The UPCV10-F41 uses a fixed 80% ratio (±5% tolerance), factory-set by spring selection, eliminating field adjustment uncertainty. The pressure setting itself is adjustable from 41.4 to 206.8 bar via a 1/4" hex Allen head, with four seal material options (Buna-N, Fluorocarbon, Polyurethane, PPDI Urethane) covering fluid temperatures from -54°C to 204°C.

Cavity and installation

The valve screws into an HVC10-F4 industry-standard 10-size 4-way cavity with an installation torque of 44.7–50.2 N·m (33–37 ft-lb). No orientation restrictions apply — the cartridge functions in any mounting position. At 0.28 kg, it adds negligible mass to a manifold block. The valve is rated for mineral-based and synthetic hydraulic fluids with lubricating properties at viscosities from 7.4 to 420 cSt, and carries 960-hour salt-spray corrosion protection per ASTM B117 on the external surfaces. Proof pressure is 482.6 bar (7,000 psi) with burst pressure at 965.3 bar (14,000 psi), providing a substantial safety margin above the 206.8 bar operating limit on ports 1–3.