Little has changed in basic crusher design over the last decades other than improvements in speed and chamber design.
Rebuilding and keeping the same crusher operating year after year has long been a typical approach. However, recent developments brought about the advent of hydraulic systems in modern crushers – innovation stimulated by the need for greater productivity, as well as safer working environments.
These hydraulic systems are engineered to deliver greater plant uptime and eliminate the safety risks associated with manual intervention.
Crushing areas are undoubtedly hazardous environments. Large material and debris can jam inside a crusher, damaging components and causing costly downtime. And manually digging out a crusher before repairs or restarts puts workers at risk.
The Mine Safety & Health Administration (MSHA) reported over the years that numerous accidents occurred when workers climbed in or under a jaw to manually clear it, make a repair, or adjust an older-style jaw crusher. Consider, too, that accidents can occur even when a machine is locked out and tagged out.
Hydraulic systems on modern crushers eliminate the need for workers to place themselves in or under a crusher. An overview of hydraulic system technology points to three key elements.
1. A hydraulic chamber-clearing system that automatically opens the crusher to a safe position, allowing materials to pass.
2. Hydraulic overload relief that protects parts and components against overload damage.
3. A hydraulic adjustment that eliminates the maintenance downtime associated with manual crusher adjustments and maintains safe, consistent crusher output without the need for worker intervention
A closer look at these hydraulic systems illustrates how each affects safe operation and increased productivity.
Hydraulic chamber clearing
Whether a crusher is jammed by large material, tramp iron or uncrushable debris – or is stalled by a power failure – a chamber must be cleared before restarting.
Manual clearing is a lengthy and risky task, especially because material can be wedged inside a crusher with tremendous pressure. Dislodging poses danger to workers placed in harm’s way inside a crusher.
Unlike that of an older-style jaw crusher, a modern crusher will clear itself automatically with hydraulics that open the crusher to a safe position and allow materials to pass – again, without the need for manual intervention. If a feeder or deflector plate is installed under a crusher, uncrushable material will transfer smoothly onto the conveyor without slicing the belt.
Hydraulic relief
To prevent crusher damage, downtime and difficult maintenance procedures, the hydraulic overload relief system opens the crusher when internal forces become too high, protecting the unit against costly component failure. After relief, the system automatically returns a crusher to the previous setting for continued crushing.
Hydraulic adjustment
A modern crusher is engineered with oversized hydraulic cylinders and a traveling toggle beam to achieve reliable overload protection and simple crusher adjustment. Closed-side setting adjustments are made with push-button controls, with no shims needed at any time. This is a key development, as many accidents have occurred during shim adjustment – a process that has no less than 15 steps as described in the primary crusher shim adjustment training program offered by MSHA.
Information for this article derived from Pit & Quarry University, an educational resource of Portable Plants’ sister publication.