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Moving vs fixed cones: understanding the differences

 

Cone crushers are an integral part of any comminution process – but how do you know if your process requires a live shaft model or a fixed shaft unit? Mark Utecht explains the differences.

Trio cone crushers, available through the Weir Group, offer robust reduction for medium or above hardness feed material and are suitable for secondary, tertiary or (if the application requires) quaternary crushing stages. These compression crushers are highly effective in typical mining applications and when processing ballast.

Inside the crushing chamber, a moving cone (the head) compresses rocks against each other and the edge of the concave bowl. This reduces multiple-sized particles at once and minimises wear.

The concave shape of the bowl ensures rocks will be crushed several times before they exit the crusher, as the volumetric space between the head and bowl gradually narrows towards the bottom of the crushing chamber.

The primary difference between the two ranges of Trio cone crushers – the TC and the TP – is the rotating parts. The Trio TC crusher’s classic live – or moving shaft – design sees the entire shaft rotate eccentrically along with the head, while in a Trio TP crusher’s design, the shaft is fixed in the mainframe while the head rotates eccentrically. The TP’s design allows it to rotate faster and facilitates more interparticle crushing than the TC series.

We are often asked: “Which cone crusher is better?” However, the answer is not as straightforward as it may seem, with factors such as the application and operating conditions determining the correct choice.

A LIVE SHAFT CRUSHER

In the Trio TC cone crusher (see Figure 1), both the shaft and the head are moved in unison eccentrically during operation. This proven design can be traced back to the original cone crushers invented in the 1920s, and a century of optimisation later, it’s one of the most reliable crushers in operation today.

Although we always recommend all cone crushers are choke-fed, the TC series’ straightforward design makes it ideal for use in applications where feed conditions are unreliable. It has a slower rotation and a smaller throw (the space between the head and the bowl) compared to fixed shaft designs. It is also less susceptible to wear from intermittent feeds which leave the crushing chamber filled below capacity.

The TC series cone crusher remains the first choice for operators looking for reliable equipment. Its robust design makes it the preferred choice for pebble crushing – one of the toughest crushing applications.

Based on a proven design, the Trio TC series cone crusher features modern, easy to use control systems. Its suitability for sub-standard feed conditions doesn’t mean this is a sub-standard cone crusher. After months of operational and design upgrades, our Trio TC is a fully automated live shaft crusher, engineered to deliver maximum efficiency. It features state of the art crushing technology with modern lubrication, power systems and optimised hydraulics. Every element has been considered in the design, from the gearing, to the motion of the shaft and eccentricity of the rotation.

Figure 1. A cross-section of the Trio TC series cone crusher, which has a live, moving shaft that rotates eccentrically with the head.

A FIXED SHAFT CRUSHER

The Trio TP fixed shaft – or pedestal – cone crusher can utilise substantially more watts, with a bigger eccentric throw and a higher pivot point to deliver throughput as high as 1000 tonnes per hour (tph). The TP series also benefits from higher percentages of interparticle crushing which enables it to produce a finer product curve compared to TC-style crushers.

The fixed shaft is more compact than live shaft designs, making it ideal for mobile applications or plants with limited clearance.

The easily adjustable closed side setting (CSS) makes it easier for operators to adapt to changing ore bodies, or for aggregate producers to achieve their preferred product. The Trio TP series cone crusher naturally creates a cubical-shaped end product that can remove the need for further crushing and shaping.

Available in short head and standard configurations offering 193kW to 671kW (or 260 to 900 horsepower), the flexible Trio TP series is suitable for any project which facilitates choke-fed crushing.

CRUSHING EXPERTISE

Weir Group consists of the experience and knowledge to specify the right equipment for mines and quarries. With two market-leading cone crushing options, together with an unrivalled service centre network and support, Weir can offer viable solutions.

Using data from applications throughout mining and aggregates, quarry producers can be supported throughout the entire process of cone crusher selection, installation, optimisation, and maintenance, from locations in more than 70 countries around the world.  

Mark Utecht is the director of Weir Group’s Comminution Technology Group.