What Exactly Is a Jaw-Roll Crusher

[MikePhua]

Cedar Rapids and the Legacy of Portable Crushing Plants
Cedar Rapids, a brand under Terex Corporation, was a pioneer in portable crushing equipment throughout the mid-20th century. Their Commander series plants were widely used in road building, military operations, and small-scale aggregate production. These self-contained units combined multiple crushing and screening components into a single towable platform, reducing setup time and transport costs.
By the 1950s and 1960s, Cedar Rapids had produced thousands of such plants, many powered by Detroit Diesel or Caterpillar engines. Their jaw-roll crusher configuration became a hallmark of compact, versatile crushing systems for contractors and municipalities.
Jaw Crusher Fundamentals
A jaw crusher is a primary crushing machine that uses compressive force to break down large rocks. It consists of two plates:

• Fixed jaw: Stationary plate mounted to the frame
  
• Swing jaw: Moving plate that pivots to crush material against the fixed jaw
  

Material enters the chamber and is crushed as the swing jaw moves toward the fixed jaw. The output size is controlled by the closed side setting (CSS), which determines the gap between the jaws at the bottom of the stroke.
Jaw crushers are ideal for hard, abrasive materials like granite, concrete, and basalt. They produce relatively coarse output, which often requires secondary crushing.
Roll Crusher Mechanics
A roll crusher uses two rotating cylinders to compress and shear material. The rolls can be:

• Smooth: For friable materials like coal or brick
  
• Corrugated or toothed: For harder or more abrasive feed
  

Material is fed between the rolls and crushed as it passes through the narrow gap. The output size is controlled by adjusting the roll spacing and speed.
Terminology annotation:

• Intermeshing rolls: Rolls with teeth that grip and pull material through
  
• Nip angle: The angle between the rolls where material is captured and crushed
  
• Recrushing: The process of reducing already crushed material to finer sizes
  

Roll crushers are efficient for producing uniform particle sizes and are often used for secondary or tertiary crushing.
Jaw-Roll Crusher Combination and Workflow
A jaw-roll crusher combines both mechanisms into a single plant. The workflow typically follows this sequence:

• Material enters the jaw crusher and is reduced to a coarse size
  
• The output drops onto a conveyor or screen deck
  
• Oversize material is routed to the roll crusher for secondary reduction
  
• Fines are collected and discharged for use or further processing
  

This setup allows for two-stage crushing in one mobile unit, reducing the need for multiple machines and conveyors. It’s especially useful for recycling brick, concrete, and asphalt, where consistent gradation is needed.
In one example from a brick plant in Ohio, a jaw-roll unit was used to crush out-of-spec bricks into reusable aggregate. The jaw handled the bulk reduction, while the roll crusher refined the product for reuse in paving mixes.
Advantages and Limitations
Advantages:

• Compact footprint for mobile operations
  
• Single power source for multiple components
  
• Reduced transport and setup time
  
• Effective for medium-hard materials and recycling
  

Limitations:

• Maintenance complexity due to tight component layout
  
• Limited throughput compared to modern multi-stage systems
  
• Wear part replacement can be labor-intensive
  
• Not ideal for high-volume or very hard rock applications
  

Operators often note that changing screen cloths or accessing internal components requires partial disassembly, which can be time-consuming.
Modern Alternatives and Legacy Use
Today, jaw-roll crushers have largely been replaced by more modular systems using cone crushers, impactors, and high-frequency screens. However, many Cedar Rapids units remain in service, especially in rural or municipal fleets.
Some are used for:

• Crushing surplus concrete from road projects
  
• Reprocessing demolition debris
  
• Producing base material for driveways and trails
  

In Montana, a county highway department still operates a Cedar Rapids jaw-roll plant purchased in the 1970s. It’s used seasonally to crush recycled asphalt and concrete, saving thousands in material costs annually.
Maintenance Tips and Retrofit Suggestions
To keep a jaw-roll crusher running efficiently:

• Inspect jaw dies and roll surfaces regularly for wear
  
• Maintain proper tension on belts and chains
  
• Grease bearings and pivot points per manufacturer schedule
  
• Replace worn screen cloths to maintain gradation
  
• Consider retrofitting with modern hydraulic systems for easier adjustment
  

Some operators have added remote start systems, LED lighting, and upgraded conveyors to extend the life of older units.
Conclusion
A jaw-roll crusher is a compact, dual-stage crushing system that combines the brute force of a jaw with the precision of a roll. Originally built for military and municipal use, these machines remain valuable for small-scale operations and recycling tasks.
While modern plants offer higher capacity and automation, the jaw-roll configuration continues to serve as a rugged, reliable solution—especially when mobility, simplicity, and versatility are key. For those with access to a Cedar Rapids unit, proper maintenance and thoughtful upgrades can keep these vintage crushers working for decades.