Mobile Crusher

Overview

A mobile crusher is a self-contained processing plant on crawler tracks that reduces large rock or demolition rubble to a saleable graded product at the point where the material is dug. By bringing the crusher to the face rather than hauling raw rock to a fixed plant, it cuts truck movements and lets a contractor produce aggregate or recycled fill directly on site. The unit described here is a tracked jaw crusher, the most common primary crushing machine for hard rock and reinforced concrete.

Material flows through the machine in a straight line. An excavator loads the Vibrating Grizzly Feeder, which meters rock into the Crushing Unit. The crushed product drops onto the Conveyor System, passes under the Overband Magnet that pulls out tramp iron, and builds a stockpile at the discharge end. The whole plant rides on the Track Undercarriage, drives off a single Diesel Powerpack, and is coordinated by the Control System.

Crushing Unit

The Crushing Unit is a single-toggle jaw crusher. Rock falls into a V-shaped chamber formed by a fixed wall and a moving wall. The Fixed Jaw Die is bolted to the Jaw Crusher Frame, while the Swing Jaw hangs on the Eccentric Shaft. As the shaft turns, its offset throw swings the moving jaw toward and away from the fixed wall, nipping and breaking the rock against the Swing Jaw Die. Both dies are manganese steel, which work-hardens under impact and is the main wear part of the machine.

The bottom of the swing jaw is supported by the Toggle Plate. This plate transmits the crushing reaction but is deliberately the weakest link: if an uncrushable piece such as a digger tooth enters the chamber, the toggle shears and saves the crusher from catastrophic damage. Two cast iron Flywheel units smooth the load, storing energy during the open part of the cycle and releasing it during the crushing stroke so the engine sees a steady draw rather than a series of spikes. Product size is set by the CSS Adjuster, a hydraulic wedge that changes the closed-side setting, the gap at the bottom of the chamber, from 40 to 200 mm without stopping the machine.

Feeder and Scalping

Feed is buffered and metered by the Vibrating Grizzly Feeder, a vibrating grizzly feeder. Rock is loaded into the Feed Hopper, whose folding walls drop for road transport. The Feeder Pan vibrates the rock forward toward the crusher mouth at a rate the control system trims to keep the chamber full but not choked. At the discharge end of the pan, the Grizzly Bars form a tapered deck that lets fines and dirt fall through and bypass the crusher entirely. This scalping protects the crusher from clay and improves product cleanliness, since the fines often carry the most contamination. The pan is driven by eccentric-weight Vibrator Drive units running on hydraulic power.

Conveyors and Magnet

Crushed product leaves the crusher onto the Conveyor System. The Main Product Conveyor is a wide troughed belt that runs under the body of the machine and out the discharge end to build a stockpile. Its rubber Conveyor Belt runs over sealed Idler Roller sets and is driven by a lagged Head Pulley turned by a hydraulic Belt Drive Motor. The frame folds for transport. A second narrow Side Fines Conveyor carries the scalped fines off to one side so they can be sold separately or stockpiled.

Where the feed is demolition concrete, the Overband Magnet is essential. The Magnet Block hangs above the main belt and lifts ferrous tramp metal such as cut rebar out of the product. A cleated Magnet Cleaning Belt carries the captured iron sideways and drops it into a separate pile, so the crushed concrete leaves the plant clean enough to reuse as road base.

Undercarriage and Mobility

The plant moves on a pair of Track Undercarriage assemblies. Each has a welded Track Frame, a sealed Track Chain with bolt-on shoes, lower Track Roller sets, and a hydraulic Track Drive Motor driving the sprocket through a planetary final drive. Travel speed is low, between 0.8 and 1.5 km/h, which is enough to reposition the crusher within a quarry or follow a demolition job across a site. For road transport the machine is loaded onto a low-loader; the conveyors and hopper walls fold to bring it within legal width and height.

Powerpack

The single Diesel Powerpack supplies everything. A six-cylinder turbocharged Diesel Engine of 200 to 350 kW drives the crusher, usually directly through a Crusher Drive Clutch that allows a soft start under the heavy flywheel inertia. The same engine drives two variable-displacement Hydraulic Pump units that power the feeder, the conveyors, the magnet, and the tracks. A combined Cooling Pack handles engine coolant, hydraulic oil, and charge air, drawing from the Hydraulic Tank and the Fuel Tank. Direct mechanical drive of the crusher with hydraulic drive of the auxiliaries is the standard layout because it puts the engine power straight into crushing while keeping the lighter functions flexible.

Control System and Operation

The Control System makes the plant safe and steady to run. A PLC Controller runs the start-up sequence, bringing belts and feeder up in the right order so the discharge clears before the crusher loads. It enforces interlocks that stop the feed if a belt stalls or pressure rises. The Operator Panel gives the operator a touchscreen view of throughput, settings, and faults. A handheld Radio Remote lets one person tram the tracks and start or stop the feeder from a safe distance during set-up.

The key control loop is crusher-level regulation. A Crusher Level Sensor watches the rock level in the chamber and trims the Vibrating Grizzly Feeder stroke to keep the crusher choke-fed, which gives the best product shape and the highest throughput. The Sensor Set also tracks hydraulic pressure and belt speed for overload and slip protection. Wear management drives the economics: jaw dies are flipped and then replaced after a few thousand tonnes, belts and idlers are inspected daily, and the closed-side setting is checked and reset as the dies wear to hold the product gradation within specification.