YW-L400/E121 Series Electro-Hydraulic Drum Brake

The YW-L400/E121 Series Electro-Hydraulic Drum Brake is a robust industrial braking system designed for applications requiring reliable, controlled stopping and holding. Unlike the "normally-open" YW-K series, the YW-L series typically operates on a spring-applied, fail-safe principle, though specific models may have variations. Here is a description based on its common configuration and the specified thruster.

Core Operating Principle:

This brake series is designed as a fail-safe, normally-closed brake. It uses an electro-hydraulic thruster (E121 model)​ as the actuator. The system works as follows:

Release (Energized):​ When the thruster's electric motor is powered, it drives a hydraulic pump. The generated hydraulic pressure pushes a piston, which compresses the internal brake springs. This action retracts the brake shoes from the drum, releasing the brake and allowing the machinery to move.

Apply (Fail-Safe, De-energized):​ When electrical power is cut off, the hydraulic pressure dissipates. The stored force of the compressed brake springs immediately forces the brake shoes outward against the inner surface of the brake drum, automatically applying the full braking force. This ensures the brake engages in a power failure or emergency stop.

Key Features:

Model Designation:

YW-L400:​ Indicates the brake series and frame size. The "L" typically designates a specific model line, and "400" likely refers to a key parameter such as the braking torque (e.g., 400 Nm) or drum diameter.

/E121:​ Specifies the integrated electro-hydraulic thruster model, which provides the actuation force for releasing the brake.

Fail-Safe Design (Spring-Applied):​ The defining safety feature. The brake is held closed by spring force and requires continuous power to the thruster to stay released, guaranteeing automatic engagement during power loss.

Electro-hydraulic Thruster (E121):​ Provides smooth, cushioned actuation. The hydraulic action absorbs engagement shocks, reduces noise, and allows for adjustable release and braking characteristics. The E121 thruster is a common model with specific performance specs.

Controllable Braking:​ The use of a thruster allows for potential control of the braking force (e.g., by adjusting the thruster stroke or using variable voltage), though it primarily operates in an on/off mode.

Automatic Wear Compensation:​ Likely includes a mechanism to automatically adjust the clearance between the brake shoes and the drum as the friction linings wear, maintaining consistent performance and reducing manual maintenance.

Durable Drum Brake Construction:​ Built with heavy-duty materials (cast iron shoes, levers, and base) for reliable operation in demanding industrial environments like mills, ports, and material handling facilities.

Typical Applications:

These brakes are standard for applications requiring secure holding and safety during power loss, such as:

Travel, trolley, and hoist brakes on overhead cranes and gantry cranes.

Holding brakes for winches, conveyors, and mining machinery.

Slewing mechanism brakes on portal cranes and excavators.

Summary:

The YW-L400/E121 is a spring-applied, electro-hydraulically released drum brake​ designed for safety-critical holding. It leverages the smooth action of an E121 electro-hydraulic thruster to disengage the brake, while relying on spring pressure for automatic, fail-safe engagement. Its primary role is to provide reliable stopping and zero-power holding for industrial machinery, ensuring safety and preventing unintended movement.

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