Pneumatic Piston (Non-Impacting)
Piston model are either non-impacting or impacting models, with the former being preferred for most applications. In both types, a piston reciprocates inside a cylinder with internal ports giving the back & forth motion without the need for special valve arrangements.
In non-impacting types, a self-generated air cushion eliminates metal-to-metal impact at each end of the piston stroke, reducing noise levels and stress on the hopper wall. Most VSS models of this type are designed as non-impacting units and are not modified impact models. As with the rotary types, regulating the air inlet pressure will change the frequency and force, but the amplitude can also be reduced by throttling the exhaust (effectively increasing the internal air cushion so that the piston doesn't travel the full length of the cylinder).