The structure of small jaw crushers (typically defined as models with a capacity <100 t/h and a feed opening width <300 mm) follows the core principles of large-scale jaw crushers but features simplified designs and an integrated layout. They are ideal for small mines, laboratories, and construction waste recycling due to their compact size, light weight, and mobility. Structurally, they still revolve around four main modules: the core crushing mechanism, transmission mechanism, lubrication system, and safety protection system. The specific details are as follows:

1. Core Crushing Mechanism (Simplified Integration, Cost Reduction)

This is the heart of the small jaw crusher. Compared to large-scale models, complex split structures are eliminated in favor of compactness.

1）Fixed Mechanism (Fixed Jaw + Frame)

• Frame：Mostly a one-piece cast steel frame (instead of the combined type used in large machines). Integrally formed, it offers high rigidity in a small volume and requires no additional assembly, making it suitable for transportation and installation. The top features the feed inlet, the bottom the discharge outlet, forming a crushing chamber internally with minimal external reinforcing ribs (not required due to lower load).

• Fixed Jaw Liner：Fixed to the inner side of the frame, made of high manganese steel (Mn13) or high chromium cast iron. It is relatively thin (usually 10-20mm) and secured by bolts and wedges for easy replacement when worn. The surface has a simple tooth profile (e.g., triangular, trapezoidal) to enhance material bite and prevent slipping.

2）Moving Mechanism (Movable Jaw Assembly)

• Movable Jaw Body：The movable component opposite the fixed jaw, made of cast steel. It is small and lightweight; some small models integrate the jaw body with the connecting rod (simplifying structure and reducing failure points).

• Movable Jaw Liner： Cooperates with the fixed liner to form the crushing chamber. Wear typically occurs more heavily at the bottom than the top. Some small models support flipping the liner upside down to extend service life.

• Eccentric Shaft (Pitman Shaft)：The core drive shaft running through the movable jaw. It has a small eccentricity (suitable for fine crushing) and is made of alloy structural steel. Both ends are mounted directly in the frame's bearing housings (no additional bearing brackets needed).

• Toggle Plate (Thrust Plate)：Small jaw crushers usually have only one rear toggle plate (simplified design). Connecting the movable jaw to the rear wall of the frame, it acts as both a power transmission component and a safety shear pin. If an uncrushable object (like iron) enters the chamber, the toggle plate breaks first to protect the eccentric shaft, frame, and other core components.

2. Transmission Mechanism (Simplified Layout, Reduced Energy Consumption)

The transmission mechanism is greatly simplified, requiring no complex reduction gearboxes, and transmits power directly via pulleys.

• Motor：Small asynchronous motors (usually 2.2-30 kW) are used. Integration with the crusher body is high; some models mount the motor directly on the side of the frame to save space.

• Pulley + V-Belt： The motor drives the pulley on the eccentric shaft via a V-belt. The pulley diameter is relatively large (to reduce speed and increase torque). Some models feature a manual tensioning device (adjusting belt tightness by moving the motor position).

• Flywheel：Often integrated with the pulley (instead of being a separate component), it stores energy, balances inertial forces, and simplifies the structure. Made of cast steel, its surface is balanced to ensure smooth operation.

3. Lubrication System (Manual, Easy Maintenance)

Due to low load and speed, small jaw crushers mostly use manual lubrication without complex automatic pumps.

• Lubrication Points： Only the bearings at both ends of the eccentric shaft (connection points between the pitman shaft and the frame) require lubrication.

• Lubrication Method： Grease is periodically injected into the grease nipples on the bearing housings using a grease gun. The cycle is typically every 8-12 hours of operation (adjustable based on conditions).

• Lubricant： Lithium-based grease is usually selected for its high-temperature resistance and water resistance, suitable for continuous operation of small equipment.

4. Safety Protection System (Simplified but Functional)

The system focuses on "equipment protection + personnel protection," featuring simple but practical structures.

1）Toggle Plate Safety Device： The core safety component. When an uncrushable object enters, the toggle plate breaks to cut off power transmission and prevent damage to core parts. It is designed for easy disassembly and replacement.

2）Protective Covers：Metal guards must be installed over rotating parts like pulleys and flywheels to prevent accidental contact.

3）Discharge Opening Adjustment： Most small crushers use a shim adjustment method (adding or removing shims between the toggle plate and the frame). The width of the discharge opening is controlled by changing shim thickness. Adjustment requires stopping the machine for safety.

5）Feed Inlet Grille：An optional simple grille to prevent oversized materials from entering the chamber and causing blockages.

5. Auxiliary Structures (Integrated Design, Mobile)

Auxiliary structures prioritize practicality and mobility for small work sites.

1）Feed Hopper： Usually a simple welded steel structure mounted on top of the frame to guide materials into the chamber. Hoppers on some models are foldable for easier transport.

2）Base：Often integrated with the frame or made of welded section steel. It can be placed directly on a flat surface (no complex foundation required). Some models are equipped with wheels for mobile operation.

3）Discharge Chute：An optional simple chute guides crushed materials to a centralized discharge point to prevent scattering.