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Are two heads always better than one?


Possibly, but when it comes to compact Inline grinders the case for twin shaft over single shaft is not necessarily as clear cut.


The essential difference is that twin shaft create the shearing action by interlacing the cutter blades on each shaft, whereas a single shaft achieves it by rotating its blades through a fixed element in the housing. In either case these cutter elements introduce an obstruction to the flow which then results in a pressure drop across the grinder unit. That pressure drop although small is typically 2-3 times greater in a twin shaft grinder.


Most, if not all, inline grinders are motor driven; if the power fails and the motor stops then the only flow possible is that which can pass through the available open space. In a twin shaft unit this is very restricted leading to the system backing up rapidly, whereas the single shaft grinders have a large open centre design as a functional necessity and allow a much greater degree of bypass.

A consequence of this open centre requirement is that the rotating blade element will have a significantly larger outside diameter than the twin shaft cutters. This increases both the peripheral tip speed and the shearing energy they generate, leading to a more efficient cutting action and a lower risk of jamming.


As with most things, the fewer number of parts involved the lower the risk of breakdown. Servicing is simpler and maintenance time and spares costs are reduced. Typically a single shaft grinder can contain up to 30% less parts than an equivalent capacity twin shaft.


Our range of DEFENDER inline grinders feature all of these advantages.


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