Mobile Crushers

A mobile crusher is a self-contained crushing plant mounted on tracks or wheels, which reduces rock, gravel, concrete and other materials to smaller sizes at the place where they are found or produced. Each unit combines a feed hopper, a crusher, conveyors and a power unit on one chassis, and it can move around a site and be transported between jobs on a low loader. Several mobile crushers and screens can be linked together to form a complete processing line.

Mobile crushers are used in quarries, in construction and demolition recycling, in road building and in mining. By taking the crusher to the material rather than hauling the material to a fixed plant, they reduce truck traffic, transport costs and emissions, and allow demolished concrete and asphalt to be reused as aggregate on the same site.

Brief History of Mobile Crushers

Mechanical rock crushers date from the nineteenth century, when the jaw crusher and then the gyratory crusher were developed to produce aggregate for roads, railways and concrete. For about a century, crushing plants were mostly fixed installations, with portable wheel-mounted plants used by road contractors and smaller quarries from the early and middle twentieth century.

Track-mounted crushers changed the industry. In 1985, Nordberg introduced the Lokotrack in Finland, a track-mounted crushing plant that could follow the quarry face, and the concept was quickly taken up by other manufacturers. Through the 1990s and 2000s, compact tracked crushers made on-site recycling of concrete and demolition waste practical, and the range of mobile jaw, cone and impact crushers grew to cover almost every application. Today most new crushing capacity for contractors and many quarries is mobile, with diesel-electric and fully electric drives, remote control and telematics becoming common.

How a Mobile Crusher Works

Feeding. Material is loaded into a hopper by a wheel loader or excavator. A vibrating feeder moves it forward and often includes a grizzly section that removes fines before crushing.
Prescreen. Many units have an independent prescreen that separates soil and small material so that only oversize rock enters the crusher.
Crushing. The crusher reduces the material by compression or impact, depending on the type. The setting, the gap that sets the product size, can be adjusted hydraulically on most modern units.
Magnet. An overband magnet removes reinforcing steel and other metal from recycled concrete.
Conveyors. A main product conveyor carries the crushed material to a stockpile or to the next machine, while side conveyors take fines or byproducts away.
Afterscreen. Some units have an onboard screen that returns oversize material to the crusher in a closed circuit and delivers a sized product.
Power and drive. A diesel engine drives the crusher directly or through hydraulics, or powers a generator for electric drives. Many units can also run from mains power.

Types of Mobile Crushers

Mobile Jaw Crushers

Jaw crushers squeeze material between a fixed and a moving jaw. They are the usual primary crusher for blasted rock and demolition concrete, handling large feed sizes and hard, abrasive material.

Mobile Cone Crushers

Cone crushers compress material between a gyrating mantle and a concave. They are used as secondary and tertiary crushers in hard rock to produce well-shaped aggregates, and need a pre-sized feed.

Mobile Impact Crushers

Horizontal shaft impactors break material by throwing it against impact aprons with rotating blow bars. They produce cubical aggregate and suit limestone, recycled concrete and asphalt, with lower cost in soft and medium rock but higher wear in abrasive stone.

Vertical Shaft Impactors

VSI crushers throw material outward against an anvil or a rock lining. They are used for shaping aggregate and producing manufactured sand.

Compact Crushers

Small tracked crushers and crusher buckets for excavators serve small contractors, demolition firms and landscaping, where volumes are low and access is limited.

Size Classes

Class	Typical transport weight	Typical capacity	Typical use
Compact	under about 25 t	up to about 150 t/h	Small recycling and demolition jobs
Medium	about 25 to 50 t	about 150 to 400 t/h	Contract crushing, recycling, small quarries
Large	over about 50 t	400 t/h and more	Quarries and mining

Figures are indicative and depend strongly on material, feed size and product.

Building a Crushing Train

Mobile crushers rarely work alone. A typical quarry setup starts with a jaw crusher as the primary unit, followed by a cone crusher as the secondary and a screen that sorts the product and returns oversize to the cone. In recycling, a single impact crusher with an afterscreen and magnet can often make a finished product in one pass. Tracked units are placed close together and connected by their conveyors, and the whole train is moved forward as the quarry face advances. Because each unit is self-contained, contractors can add or remove machines to match changing jobs, which is one of the main advantages of mobile plants over fixed installations.

Main Manufacturers

Metso, maker of the Lokotrack range.
Sandvik, with tracked jaw, cone and impact crushers.
Kleemann, part of the Wirtgen Group.
Terex, with the Powerscreen, Finlay and EvoQuip brands, among others.
Keestrack, Rubble Master, McCloskey and Rockster, with wide mobile ranges.

Main Uses of Mobile Crushers

Primary and secondary crushing in quarries.
Recycling of concrete, brick and mixed demolition waste.
Processing of asphalt planings for reuse.
Crushing rock excavated on construction and road projects.
Contract crushing for aggregates producers.
Mining, including crushing near the face to reduce truck haulage.

Choosing a Mobile Crusher

Know the material. Hardness, abrasiveness, moisture and the presence of steel or wood decide between jaw, cone and impact crushers.
Define the product. The required size, grading and shape of the final aggregate set the number of crushing stages and the screens needed.
Balance the line. Feeding equipment, crushers and screens should match in capacity so that no machine waits for another.
Consider wear costs. Jaw plates, blow bars and cone liners are major running costs, especially in abrasive rock.
Think about mobility. Frequent moves favour compact, quickly set up machines, while long jobs at one site may justify larger units or electric operation.

Safety

Mobile crushers combine large moving parts, heavy material flow and high energy. Blockages in the crushing chamber are a common hazard, and they must only be cleared with the machine isolated and locked out, using proper tools rather than by hand. Guards on conveyors and drives, emergency stop cords, safe access platforms and lockout procedures are essential. Flying rock, dust containing crystalline silica and noise require exclusion zones, dust suppression and hearing protection. Loading machines should work from a safe position, and the operator should be able to stop the crusher by remote control. Moving the crusher on tracks requires a clear path and a banksman.

Trends and Technology

Mobile crushers are increasingly electrified, with diesel-electric drives that can be switched to grid power when available. Automation adjusts crusher settings and feed rate to keep the chamber full and protect the machine from overloads, and linked plants share control so that one machine can slow down the others. Telematics report production, fuel use and maintenance needs. Recycling applications are growing as regulations favour the reuse of construction waste, and hybrid and battery solutions are being tested for sites with emission limits.

Dust suppression with water sprays at transfer points, noise enclosures and lower-emission engines are also becoming standard, helping mobile plants work closer to homes and in urban recycling yards where planning conditions are strict.

Key Terms

Closed side setting (CSS): the smallest gap in the crushing chamber, which largely controls product size.
Reduction ratio: the ratio between feed size and product size.
Choke feeding: keeping the crushing chamber full for efficient cone crushing.
Blow bars: wear parts on the rotor of an impact crusher.
Overband magnet: a magnet above the conveyor that removes steel from the product.
Closed circuit: a setup in which oversize material returns to the crusher.

Frequently Asked Questions

What is the difference between a jaw crusher and an impact crusher? A jaw crusher breaks material by compression and accepts large, hard feed. An impact crusher breaks it by high-speed blows and gives a more cubical product, but wears faster in abrasive rock.

Can a mobile crusher process reinforced concrete? Yes. Jaw and impact crushers with overband magnets are commonly used to crush reinforced concrete and remove the steel.

Do mobile crushers need a screen? A crusher alone produces a mixed grading. A screen is needed to separate products of defined sizes, either on board or as a separate machine.

How is a tracked crusher transported? Most units travel on a low loader and are designed to meet road transport dimensions after folding conveyors and hoppers.

Are mobile crushers as productive as fixed plants? Large mobile units can reach high capacities, but very large, long-term operations still often use fixed or semi-mobile plants. Mobile crushers are chosen for flexibility, lower setup cost and reduced haulage.