The YZA20-8 series hydraulic power unit is a compact, integrated hydraulic system designed to provide stable pressure and flow for industrial braking, clamping, and lifting mechanisms (e.g., matching YFX wedge brakes, YLZ wheel brakes, and rail clamps). It features a small footprint, low noise, and reliable operation, suitable for outdoor port, crane, and metallurgical equipment. Below is a detailed overview of its core parameters, structural features, working principle, maintenance guidelines, and common faults & solutions.
Core Technical Parameters
| Parameter | Standard Value | Notes |
|---|---|---|
| Rated working pressure | 20 MPa | Max pressure for continuous operation |
| Rated flow | 8 L/min | Flow output at rated pressure |
| Motor power | 3 kW | 3-phase AC 380V/50Hz, IP55 protection |
| Tank capacity | 40 L | Integrated oil tank with level gauge |
| Hydraulic oil type | ISO VG46 anti-wear hydraulic oil | Low-temperature ISO VG32 optional for -25℃ environments |
| Working medium temperature | -20℃ to +55℃ | Oil temp must not exceed 60℃ during operation |
| Control voltage | AC 220V/DC 24V | For solenoid valve actuation |
| Protection features | Overpressure relief, oil level alarm, overheat protection | Safety interlock with host equipment |
| Weight | ~120 kg | Compact integrated design |
| Compliance standard | GB/T 3766-2015 (Hydraulic system general requirements) |
Key Structural Features
Integrated Modular Design
Combines motor, gear pump, oil tank, solenoid valve block, relief valve, filter, and pressure gauge into one unit, eliminating external pipelines and reducing leakage risks.
The solenoid valve block integrates directional control valves, check valves, and throttle valves, enabling precise control of oil flow direction and speed for connected actuators (e.g., brake cylinders, rail clamp jaws).
Multi-Level Safety Protection
Overpressure relief valve: Automatically unloads when pressure exceeds 22 MPa (10% above rated pressure) to protect the pump and pipeline from burst damage.
Oil level sensor: Triggers an alarm when oil level drops below the MIN mark, preventing pump cavitation.
Oil temperature sensor: Shuts down the motor if oil temp exceeds 65℃, avoiding oil deterioration and seal aging.
High-Efficiency Filtration System
Equipped with a suction filter (100 μm) and return filter (25 μm) to remove impurities from the oil circuit, extending the service life of valves and pumps.
The return filter has a pressure difference indicator-when the indicator turns red, the filter element must be replaced immediately.
Easy Maintenance & Installation
Transparent oil level gauge and drain plug for quick oil level checks and oil changes.
Flange-mounted design for direct installation on the host equipment frame; oil outlet/inlet ports use standard threaded connections for easy matching with actuators.
Working Principle
The YZA20-8 series operates as a constant-pressure supply system for brake/rail clamp hydraulic actuators, with three core working states:
Pressure Build-Up State (Release Brake/Rail Clamp)
When the host equipment (e.g., crane) needs to start, the control system sends a signal to energize the solenoid valve.
The motor drives the gear pump to draw oil from the tank, pressurize it to 20 MPa, and deliver it to the actuator (e.g., brake cylinder). Hydraulic pressure pushes the piston to release the brake/rail clamp.
When pressure reaches the rated value, the pressure switch sends a signal to stop the motor (or switch to pressure-holding mode) to save energy.
Pressure-Holding State (Equipment Operation)
The check valve in the solenoid valve block maintains pressure in the actuator circuit, ensuring the brake/rail clamp remains released during equipment operation.
If pressure drops due to minor leakage, the pressure switch triggers the motor to restart and replenish pressure automatically.
Unloading State (Braking/Clamping)
When the host equipment stops, the solenoid valve de-energizes, and the oil circuit is connected to the tank.
Hydraulic oil in the actuator flows back to the tank under the action of the brake's disc spring or rail clamp's clamping spring, and the actuator resets to achieve braking/clamping.
