(57) A hot melt adhesive pump having a first stage gear pump for metering molten hot melt
adhesive into a second stage gear pump where gas is mixed and driven into solution
with the adhesive is provided with ports extending between opposed gear faces permitting
the leakage of adhesive under pressure between gear faces. Pressure imbalances which
might otherwise exist due to the accumulation of hot melt adhesive in an interface
between the gear faces and adjacent surfaces, e.g., a pair of plates, between which
the gears are sandwiched, are alleviated because adhesive under pressure in this interface
can pass through the ports, thereby balancing the thrust forces on the opposed gear
faces. The result is reduced gear and end plate wear and increased pump life.
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