PRA-8A-2D-Y-Z-74 Winner Hydraulics Inverse Proportional Pilot Relief Valve
The Winner Hydraulics PRA-8A-2D-Y-Z-74 is an inverse direct-acting, poppet-type electro-proportional relief valve with pilot capacity, for the 8A-2 cavity. It is spring-biased closed to its highest pressure setting. As coil current increases, the pressure setting falls proportionally. The valve therefore delivers high pressure with no command, a fail-to-high-pressure behaviour often specified for pilot control of larger relief main stages. It is rated to 350 bar with a 1 L/min rated pilot flow (2 L/min maximum).
Inverse Proportional Operation
The poppet stays seated until pressure at port 1 overcomes the spring force minus the solenoid force, which is set by the analog input signal. At that point it lifts and allows flow from port 1 to port 2. With zero current, the valve holds the highest setting of the selected range. Raising the current lowers the relief pressure in proportion. Back pressure at port 2 (tank) adds to the setting at a 1:1 ratio.
PRA-8A-2D-Y-Z-74 Technical Data
| Specification | Value |
|---|---|
| Valve type | Inverse direct-acting, poppet-type, pilot capacity proportional relief valve |
| Function | High pressure setting with no command |
| Cavity | 8A-2 |
| Thread | M16 x 1.5 |
| Rated flow | 1 L/min (0.26 gpm) |
| Maximum flow | 2 L/min (0.53 gpm) |
| Max. operating pressure | 350 bar (5000 psi) |
| Valve hex size | 22.22 mm (7/8 in) |
| Installation torque | 27–33 Nm (20–24 lbf-ft) |
| Max. leakage at reseat | Approx. 25 cc/min |
| Reseat | Exceeds 85% of cracking pressure |
| Hysteresis with DC input | < 8% |
| Hysteresis with dither | < 4% |
| Linearity with dither | < 2% |
| Recommended dither frequency | 100–250 Hz (best range 140–200 Hz) |
| Coil | EC-19A, 22 W, 19 mm tube (ordered separately) |
| Weight | 0.211 kg (without coil) |
Pressure Ranges (Y) and Factory Defaults
| Y code | Adjustment range | Factory default setting (at 0.4 L/min) |
|---|---|---|
| W | 350–210 bar | 210–215 bar |
| A | 210–105 bar | 140–145 bar |
| B | 105–55 bar | 70–75 bar |
| D | 55–20 bar | 28–30 bar |
The factory setting is based on use with Winner’s RV-11A main relief valve. To get the setting right first time, specify the required pressure and the main valve you will use when you order.
Option Code (Z)
- L: standard type with leakproof hex socket adjustment screw
Features
- Inverse proportional control: high pressure at zero current, lower pressure as current rises
- Poppet-type design for pilot-stage pressure control
- Four pressure ranges, from 20 bar up to 350 bar
- Continuous-duty rated coil and efficient wet-armature construction
- Low hysteresis (< 4%) and good linearity (< 2%) with dither
- Heat-treated, high-precision ground working parts
- WINNERcoat® zinc-nickel plating, salt-spray tested to DIN EN ISO 9227 for up to 1000 hours
- Pressure rating tested to NFPA T2.6.1, with 90/90 fatigue rating assurance
- 100% functional test before shipment
- Multiple seal kit materials available
For best performance, Winner recommends driving the valve with a current-sensing amplifier with a dither function.
Main Stage Valves Paired with the PRA-8A-2D-Y-Z-74
Winner Hydraulics lists the PRA-8A-2D-Y-Z-74 as a proportional pilot for its relief main stages with integral 8A control cavity, including:
- Balanced poppet (RP-2G-8): RP-10A-2G-Y-8, RP-3A-2G-Y-8, RP-16A-2G-Y-8, RP-18A-2G-Y-8
- Balanced piston (RP-20-8): RP-10A-20-Y-8, RP-3A-20-Y-8, RP-16A-20-Y-8, RP-10W-2S-Y-8, RP-22MA-2S-Y-8
- High flow: RP-18A-20-Y-Z, RP-18A-20-Y-Z-76
PRA-8A-2D-Y-Z-74 vs. Other 8A-2 Proportional Pilots
| Model | Function at zero current |
|---|---|
| PRA-8A-2D-Y-Z-74 | Inverse: high pressure with no command |
| PRA-8A-2C-Y-Z | Inverse: high pressure with no command |
| PRB-8A-2D-Y-Z / PRB-8A-2C-Y-Z | Standard direct-acting: low pressure with no command |
Buy the PRA-8A-2D-Y-Z-74 Winner Hydraulics
Atlantech Drives supplies genuine Winner Hydraulics proportional cartridge valves worldwide, with fast shipping. Tell us the pressure range (W, A, B or D), the required setting, the main valve and the coil voltage, and our commercial team will confirm availability, pricing and lead time for the valve and its EC-19A coil. Request your quote today.
