Vibratory apparatus

Claim 1

In combination with a vibratory apparatus having a work member supported on isolation springs, an exciter connected to the work member by a spring system for imparting a vibratory, stroke-generating force to the work member, a constant speed electric motor carried by the exciter, a shaft driven by the motor, a counterweight wheel carried at each end of the shaft, a fixed eccentric weight on each counterweight wheel, a movable weight means on each counterweight wheel, said movable weight means including a first fluid reservoir on the counterweight wheel on one side of the axis of rotation thereof, a second fluid reservoir on the counterweight wheel on the other side of said axis and adjacent the fixed eccentric weight the second reservoir being closer to said axis than the first reservoir, a fluid conduit interconnecting the reservoirs, the positions of the reservoirs relative to the axis biasing the fluid in the second reservoir to flow through said conduit to the first reservoir upon rotation of the counterweight wheel, a diaphragm in the first reservoir dividing the reservoir into a first chamber containing said fluid and a second chamber, control means comprising a hydraulic fluid conduit connected to said chamber, a hydraulic pump having its discharge connected to said conduit, a hydraulic fluid reservoir, means connecting the intake of the pump to the hydraulic reservoir, signal generating means for generating an electrical signal reflecting the length of stroke of the work member, a controller for comparing the signal of the signal generating means with a signal reflecting the desired stroke, a first solenoid operated valve for controlling the connection between the pump and said conduit, a second solenoid operated valve for connecting said conduit to the reservoir and means controlled by said controller for operating said valves.