Excavator Hydraulic Pump 708-1W-00131 708-1W-00042 Komatsu PC60-7 Main Piston Pump Komatsu PC60-7 Hydraulic Pump Common Faults The main pump of Komatsu PC60-7 is HPV55 variable displacement piston pump. Root causes of frequent failures for this model include contaminated hydraulic fluid, suction-side air ingress, and seized power regulator spool. Sluggish operation, insufficient machine output and low system pressure Symptom: Normal operation at no-load; pressure drops