External Hydraulic Gear Pumps

External Gear Pumps can come in single or double (two sets of gears) pump configurations with spur (shown), helical, and herringbone gears. With four bearings in the liquid and tight tolerances, they are not well suited to handling abrasive or extreme high temperature applications. External gear pumps have close tolerances and shaft support on both sides of the gears. Large-capacity external gear pumps typically use helical or herringbone gears. Small external gear pumps usually operate at 1750 or 3450 rpm and larger models operate at speeds up to 640 rpm. Helical and herringbone gears typically offer a smoother flow than spur gears, although all gear types are relatively smooth.