How does a reversible hammer crusher work?

The reversible hammer crusher‘s operating principle is based on impact crushing and bidirectional rotation. High-speed rotating hammers exert impact force on the material, combined with the reversibility of the rotor to achieve efficient and uniform crushing. The following is a detailed explanation of its working principle:

1. Core Crushing Mechanism: Impact Crushing

Material Entering the Crushing Chamber

Material enters the crusher through the feed inlet and first comes into contact with the high-speed rotating hammers. These hammers impact the material at a linear speed (typically 25-70 m/s), causing initial crushing.

Secondary Crushing and Shaping

The crushed material gains kinetic energy and strikes the impact plate or liner at high speed, causing secondary crushing. Some of the material also collides with subsequent incoming material, causing autogenous grinding, further refining the particle size and improving the particle shape.

Discharge Control

Sieveless Design: The discharge particle size is controlled by adjusting the gap between the hammers and the impact plate, avoiding the clogging problem of traditional screen plates caused by high material moisture. Screen Bar Structure (Select Models): If equipped with screen bars, materials must meet the required particle size before passing through the screen openings. Substandard materials will continue to be crushed within the crushing chamber.

2. Innovative Design of the Reversible Rotor

Bidirectional Rotation

The rotor can operate in both directions, allowing the hammer’s working surface (impact surface) to be used in both directions. When one side is severely worn, the rotor can be reversed to continue crushing on the other side, extending the hammer’s life by 30%-50%.

Bidirectional rotation also balances rotor forces, reducing equipment vibration and improving operational stability.

Solving the Problem of Unidirectional Wear

Traditional crushers’ hammers are subject to force in only one direction, which can easily lead to localized excessive wear. The reversible rotor alternates the working surfaces on both sides, evenly distributing wear and reducing replacement frequency and cost.

3. Synergistic Effects of Key Components

Hammer

Material: Typically made of high-chromium alloy or wear-resistant cast steel, they combine high hardness and toughness, making them suitable for crushing medium-hard and brittle materials.

Shape: Mostly “T” or “X” shaped, increasing the impact area and improving crushing efficiency.

Impact plate
Installed within the crushing chamber, it controls the discharge particle size by adjusting the gap with the hammers.
Some models feature an adjustable impact plate, allowing for quick adjustment of the gap via hydraulic or mechanical means.
Liner
Protecting the crusher casing from material wear, it is typically made of high-manganese steel or rubber, extending the equipment’s service life.
Drive system
Composed of a motor, a hydraulic coupling (or pulley), and a rotor. The hydraulic coupling shortens startup time, reduces current surges, and prevents power overload.

4. Workflow Diagram
Startup Phase
The motor accelerates the rotor to the rated speed (typically 500-1000 rpm) through the hydraulic coupling.
Feeding and Crushing
Material enters the crushing chamber through the feed port → High-speed hammers impact and crush → Material impacts the impact plate for secondary crushing → Autogenous grinding refines the particle size.
Discharge and Circulation
Qualified material is discharged through the gaps or sieve holes → Substandard material continues to circulate and be crushed within the crushing chamber. Reverse Operation (Optional)
When one side of the hammer head becomes severely worn, the machine stops and the rotor reverses, switching to the other working surface to restore crushing efficiency.
5. Technical Advantages
High Efficiency and Energy Saving
With a high crushing ratio (up to 20), a single unit can perform both secondary and tertiary crushing, simplifying process steps.
The screenless design reduces energy consumption, saving 15%-20% compared to traditional crushers.
Adaptability
Can handle materials with a moisture content of ≤15%, preventing clogging with high-moisture materials.
Suitable for medium-hard and brittle materials such as coal, limestone, coke, and gypsum.
Easy Maintenance
The hydraulic double-sided cover design simplifies maintenance, reducing hammer head replacement time to within 2 hours.
The modular structure facilitates quick replacement of wearing parts, minimizing downtime.

6. Typical Applications
Mining Industry: Crushing limestone and dolomite to meet cement production raw material requirements.
Power Industry: Fine crushing of coal gangue to optimize combustion efficiency and reduce emissions.
Building Materials Industry: Medium crushing of gypsum and clinker to improve product quality. Environmental Protection: Crushing construction waste for resource utilization.
Summary
The reversible hammer crusher, through its core design of impact crushing and reversible rotors, achieves efficient, uniform, and cost-effective crushing. Its bidirectional rotation function not only extends the life of consumable parts but also enhances the machine’s adaptability, making it a versatile tool in the industrial crushing field. With advances in materials science and intelligent technology, this equipment is becoming more wear-resistant and intelligent, providing stronger support for global industrial production.