Excavator Hydraulic Pump 21W-60-22111 Komatsu PC75UU-2 PC75UD-2 Main Piston Pump Komatsu PC75UU-2 Hydraulic Pump Common Faults The main pump is an A10VD43 variable displacement piston pump fitted with a tandem gear pump. Primary failure causes for this legacy model include contaminated hydraulic fluid, suction-side air ingress, and seized regulator assemblies. 1. Sluggish Operation, Insufficient Output Pressure Symptom: Normal no-load function; marked pressure degradation