Understanding the Key Parts of a Jaw Crusher and Their Functions

A jaw crusher is a vital piece of equipment in the mining, construction, and aggregate industries. It’s designed to reduce large materials, such as rocks, into smaller, more manageable sizes. Understanding the parts of a jaw crusher is crucial to maintaining its efficiency and performance. Let's dive into the essential components and their functions.

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1. Jaw Plates

The jaw plates are one of the most critical components of a jaw crusher. There are two types: the stationary (fixed) jaw plate and the moving (swing) jaw plate. These parts come into direct contact with the material and are responsible for breaking it down. The material used for jaw plates is usually manganese steel due to its high resistance to wear and tear. Over time, the jaw plates will wear down, which is why regular replacement is crucial for maintaining efficient operation.

2. Swing Jaw

The swing jaw is the moving part that helps crush the material. It's attached to a mechanical arm that allows it to move back and forth, creating a crushing motion. This motion is what reduces the size of the material fed into the crusher. The swing jaw is positioned opposite the stationary jaw plate and works together with it to generate the crushing force.

3. Pitman

The pitman is a crucial part that connects the moving jaw with the eccentric shaft. It is the component that moves the jaw and provides the force necessary to crush the material. The pitman is driven by the eccentric shaft, which, in turn, is powered by the flywheel. Its performance directly affects the efficiency of the jaw crusher.

4. Frame

The frame serves as the backbone of the jaw crusher. It supports the other components, providing structural integrity and ensuring that the machine remains stable during operation. The frame is typically made of cast steel or another durable material to withstand the pressures of the crushing process.

5. Eccentric Shaft

The eccentric shaft is one of the most important parts of a jaw crusher, as it is responsible for creating the motion necessary for the crushing action. It is mounted on bearings and connects to the flywheel. As the eccentric shaft rotates, it causes the swing jaw to move back and forth, which facilitates the crushing process.

6. Bearings

Bearings are used to ensure smooth operation by reducing friction between moving parts. In a jaw crusher, bearings are located at strategic points, such as on the eccentric shaft, and help maintain stability during high-stress operations. They need to be lubricated regularly to avoid wear and prevent mechanical failure.

7. Flywheel

The flywheel stores energy and helps smooth the operation of the crusher. As the eccentric shaft rotates, the flywheel helps maintain momentum, ensuring that the jaw crusher operates efficiently and consistently, especially when crushing tougher materials.

8. Wedges and Tension Rods

Wedges and tension rods help secure the movable jaw in place. These parts maintain the correct jaw alignment during operation and ensure the machine's structural integrity. When the tension rod is tightened, it ensures that the movable jaw remains in position during the crushing process.

9. Lubrication System

Proper lubrication is essential for all moving parts of a jaw crusher. The lubrication system ensures that the components, such as the eccentric shaft and bearings, are well-lubricated, reducing friction and extending the lifespan of the parts.

10. Maintenance and Replacement of Jaw Crusher Parts

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Understanding the wear and tear on parts of a jaw crusher is essential for maintaining optimal performance. Regular inspections, lubrication, and timely replacement of components like jaw plates, bearings, and the eccentric shaft are key to reducing downtime and maximizing efficiency.

By regularly checking the parts of a jaw crusher, you can ensure the machine runs efficiently and reduces the risk of costly repairs. Proper maintenance practices not only extend the life of your crusher but also increase its productivity, saving both time and money in the long run.

Jaw Crushers are ubiquitous in Quarrying, Mining and Recycling across the world. Their widespread use can be attributed to their ease of use, simple design and powerful mechanical principles to achieve material and rock resizing.

Invented back in by Eli Whitney Blake patented the Blake Jaw Crusher and is a testament to its sound mechanical engineering as it forms the basis of all modern Jaw Crushers today.

In terms of brute strength and simplicity, the Jaw is unsurpassed and is a common sight in heavy-duty rock and ore crushing.

Today Single Toggle Jaw Crushers have been refined from this 160-year-old design. Using the Keestrack B4 as an example; we can see how modern technologies and design improvements further the field of high production material processing.

A Jaw Crusher uses compression-based crushing to resize material, unlike an Impact Crusher which uses impacts to break up material. In a V configuration, the Jaw Crusher has one Fixed Jaw and one Moveable Jaw. The Moveable Jaw (also known as a Swing Jaw) pivots on an Eccentric Shaft at the top of the Jaw; this has the effect of a 'rocking motion'. The motion carries down the Jaw where it also moves the bottom portion of the Swing Jaw.

Jaw Crushers are simply set by adjusting the C.S.S. (Closed Side Setting), the C.S.S. is the width of the opening during the compressive stroke (the stroke pushing the rock against the fixed Jaw).

The reverse of this is the O.S.S. (Open Side Setting), the O.S.S. is the width of the opening during the open stroke, where the swing jaw is pulling away from the fixed Jaw. This setting is not adjustable; its distance is dependent on the physical size of the Jaw Crusher and Eccentric Throw.

Jaw Crushers reduction ratio is dependent on the actual size of the crushing chamber/box, the larger the opening for feed material, the larger the minimum C.S.S. will be. This is due to the geometry of larger boxes having a larger feed opening, and the feed exit scales up with it.

The Possible C.S.S. range on a Keestrack B4 is 45mm to 160mm. If the C.S.S. is reduced while maintaining a large feed size of 400mm machine load will go up as more energy is needed to complete the Swing Jaws rotation around the Eccentric Shaft.

The ideal Reduction ratio for Keestracks range of Jaw Crushers is 3:1, this is where it is mechanically at its optimum and will produce material efficiently and at a high throughout. At 3:1 it will handle nearly any type of material, particularly hard stone and rock. For medium hardness material the Keestrack range can produce a 5:1 reduction ratio and with soft material like asphalt and lime it can produce an 8:1 reduction ratio.

What separates Keestrack apart from other mobile Jaw Crushers is the extensive development and refinement of the mechanism and introduction of intelligent features that protect the components and reduces possible downtime.

Keestrack implements a full Digital P.L.C. control and monitoring unit on all their crushers, and the Jaw Crusher line is no exception. One of the key benefits is that the P.L.C. will automatically control the feeder to maintain high throughput based on the operators desired input. The P.L.C. monitors and adjusts the Apron Feeder, Jaw Drive and the Non Stop System for high production and in line with the operator set parameters.

One of Keestrack's flagship features if the Non Stop System (N.S.S.) which encompasses a flew slew of hydraulic adjustment and electronic monitoring systems.

1. It allows on the fly C.S.S. adjustments while crushing, which means that small adjustments or substantial changes can be done without having to stop the crushing process.
   
   
2. It incorporates a monitoring sensor which shows the actual C.S.S. of the Jaw to the operator. Whereas most other systems make the operator manually inspect it, to see what it's set and performing too.
   
   
3. Every 20-50 hours the crusher completes a Jaw reset where the P.L.C. resets the Jaw and C.S.S. according to the wear on the Jaw Plates. The gap setting will always be accurate, regardless of plate wear.
   
   
4. The systems automatic C.S.S. recovery monitors the set Gap, and if it is pushed back by more than 10mm, the system will attempt to readjust it back to the programmed C.S.S.. If readjustment is unsuccessful and hydraulic pressure on the Gap adjustment rams continues to rise, the system will stop pressurising these rams. Simultaneously the P.L.C. actuates the counter tension ram which pulls the Swing Jaw as far open as possible to dump the uncrushable material.
   
   
5. The Non Stop System has two overload protections. The first of which is electronic as described above. It also has an instantly operable mechanical relief system. It incorporates 600 Bar pressure relief valves on the cylinders. Should an uncrushable piece of material enter the chamber before the electronic system can adjust for it; the mechanical system prevents damage to the crushing chamber and importantly, their components. Both of these systems also stop the Feeder and Eccentric drive, stopping material pile up.
   
   
6. Lastly, the Gap adjustment cylinders can be manually operated to crush material that is blocking regular crushing action. This prevents the need for someone to manually unblock the crusher, making it safer and reducing potential downtime.
   
   

The Keestrack line of Jaw Crushers are true mobile quarrying and processing machines, highly capable and designed for performance. They save companies money.

How the Keestrack range of Jaw Crushers achieve a more profitable product:

Less Fuel Usage

Keestrack's Jaw Crusher range feature Load Sensing Pumps that distribute hydraulic power to components accordingly. This feature doesn't restrict hydraulic flow; rather, it directs the pumps to generate and direct hydraulic power when it's needed. This system saves companies around 20-25% in fuel costs, which can add up to around $10,000 a year.

Automation

Sensors located throughout the machine monitor load, fill levels and capacity. The P.L.C. can report on what the Jaw Crusher is doing at any moment in addition to working in the set range, keeping the crusher running efficiently and at capacity.

Smart Features

The smart features add to the Jaw Crushers productivity. The wireless remote enables total machine adjustment and even tracking while crushing.

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