What to Expect from Contemporary Horizontal shaft impact Crushers

The Horizontal Shaft Impactor (HSI) is a powerful, compact machine that has transformed the approach to crushing across industries.  There are many varieties of HSI, with a few differentiating elements.

The horizontal rotors with breaker bars are externally fed and propel material into a process of apron-mounted breaker plates. These split or macerate a variety of materials from fine to medium sizes.


The great-grandfather of HSIs is the Andreas Impact Crusher System. Dr Erhard Andreas of Muenster, Germany, patented his design in 1946, which cleverly repurposed old torpedo tubes and steel from decommissioned tanks!


This amazing package of power has reduction ratios of up to 30:1 in a single stage. The design delivers low capital and operating costs as well as low headroom requirements making the easy installation even easier.

By changing the rotor speed and changing the clearances between rotor breaker bars and apron breaker plates output size is changed.

Soft, non-abrasive materials (limestone, phosphate, gypsum, weathered shales), as well as harder minerals, can be processed by the alloy steel rotor breaker bars. There are different crushing chamber designs.  Knowledge of the application for proper feed, crushing chamber configuration, the metallurgy of the crushing chamber components, gap setting and rotational speed is needed before choosing a specific machine.


The lined crushing chamber with a rotating breaker bar rotor is on a horizontal axis. The output is a more cubical product. This is a faster impact fracture versus slower compression breaking in a cone or jaw crushers.

After loading the original product into the primary crushing chamber, the rotor breaker bars crush the feed against the first apron lined with breaker plates. The rotor, the breaker plate, and inter-particulate collision all contribute to comminution.

The material leaves the primary chamber which does the bulk of the reduction, passes the front apron breaker plate gap to enter the secondary and/or tertiary chambers.  Aprons are shaft suspended allowing for continuous gap adjustment as wear occurs.      

When the configuration is optimized material is delivered to each row of rotor breaker bars in a continuous bed over the width of the rotor. 


Use an HSI for material with compressive strength less than about 20,000 lb/sq in such as gravel or rock for roadways, railways, electrical grid isolation, construction, metal reclamation and recycling.

Log the wear history of parts including measurements, maintenance schedules, feed and discharge information and throughput rates.     

By using heaters and air cannons to reduce and dislodge material sticking to the crushing components you can process materials with high moisture content.


HSIs have proven they are highly diverse in their ability to execute size reduction for a variety of materials.  They require minimal maintenance and have excellent cubical particle size distribution control.  Mormak carries horizontal shaft impact crusher spare parts to keep your machines meeting fine and medium aggregate goals. See our article on maintenance.

Contact our Mormak aggregate experts today for advice or training on horizontal shaft impact crushers or other crushers that will give your production the best results at the best price.