Down-hole torpedo-shaped vibrators for soil compaction are generally termed vibroflots.  The vibroflots generate a horizontal mode of vibration.  TerraSystems owns both hydraulic and electric vibroflots for soil compaction. 

Our electric vibroflots operate at a frequency of 30 Hz and our hydraulic units operate at frequencies of up to 50 Hz.  The diameter of the units vary from 12 inches to 16 inches.