How the hydraulic RAM enhances productivity in industrial shredders
In industrial shredders productivity, measured as the amount of material processed per unit of time (tons/hour), is a critical characteristic defining the shredder's effectiveness. Several interconnected elements contribute to this outcome, assuming the usage is consistent with its intended purpose:
However, it often happens that for certain materials, a particular phenomenon occurs: the material tends to "float" over the blades (e.g., with cylindrical drums), or in other cases, a "bridge" forms (e.g., with cardboard) between the walls of the loading hopper. As a result, the blades fail to grasp and shred the material, implicitly reducing the shredder's productivity.
A common problem, an effective solution
Fortunately, there is a solution to this problem, involving pushing the material against the blades so that the blade tips can catch and then grind it. This accessory is called a hydraulic RAM, and it operates exactly as described: pushing, deforming, and holding the material against the blades. It is installed on one side of the hopper, opposite the load, on the side parallel to the blade shafts (taking into account the slow and fast shaft of the shredder in some models). There are fundamentally two types: arc or linear.
Versatility and precision: the two types of RAMs
Arc RAMs perform an arched movement from outside the hopper to the inside, a few centimeters away from the blades. Linear RAMs slide on skids from top to bottom inside a slot on the side of the hopper. In both cases, the starting position is called the top dead center (TDC), and the end point is the bottom dead center (BDC), beyond which the RAM stops and changes direction.
The RAMs are powered by one or more hydraulic cylinders, depending on the necessary force. A hydraulic power unit of a few kilowatts activates the cylinders.
The choice between the two types of RAM depends on the material, the shape of the hopper, the available space around it, and how the material is loaded into the hopper. The arc RAM is somewhat bulky but structurally simpler than the linear one.
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The working cycle of the RAM
The hydraulic RAM performs a work cycle from the top dead center to the bottom dead center and back, called the RAM cycle, usually managed by a Programmable Logic Controller (PLC). The cycle proceeds unimpeded when the RAM reaches the BDC without encountering significant resistance from the material, while it is simultaneously ground by the blades. If, on the other hand, the RAM is obstructed by the material for some reason, a suitably calibrated pressure switch intervenes to stop the cycle and protect the RAM. In this case, the RAM repeats short pressure cycles to try to continue its course, and if this continues to be unsuccessful, it interrupts the cycle and returns to TDC, generating a blocking alarm.
If during the RAM cycle, during the pressing phase, the blade shafts perform a reversal, the RAM interrupts the cycle until the shafts resume the working direction of travel.
Practical application: shredding industrial waste
A practical application of the above is in the shredding of mixed industrial waste. In a concrete example, a 100 HP two-shaft industrial shredder with a single hydraulic drive is used. The shredder is equipped with a 5.5 HP hydraulic arc RAM. Everything is managed by a single control panel equipped with a PLC.
The video shows the typical RAM cycle in its course from top to bottom and back. Although this is a cycle without material, the video gives an idea of the general functioning of this particular accessory, very useful for maintaining the shredder's productivity at nominal levels.
The hydraulic RAM is built in sturdy welded steel construction, and at the terminal part, in contact with the material, is placed what is called the push plate. A single hydraulic cylinder is sufficient in this case to apply the necessary thrust force on material of a few thousand kilograms.
Contact us for more information
For more details about our offerings and to discover how RAMs can improve your production process, visit our website and YouTube channel for demonstration videos, or contact our sales team directly. We are here to help you find the perfect shredding solution for your needs.