Any engine will experience a drop in power output after prolonged use. This is primarily caused by the wear of key components—such as pistons, piston rings, and cylinder liners—resulting from extended operation; the standard remedy is to replace these parts. However, since specific conditions vary among manufacturers, users, and individual machines, the measures taken must be tailored to the specific
Caterpillar ET 2026A & 2019C Electronic Technician Diagnostic Software Download and Installation
equipment to avoid unnecessary waste. The hydraulic system of a CAT excavator is supplied by a main pump driven by the engine; this main pump assembly consists of upper and lower sections, both of which are swash-plate type piston pumps. Each section features a regulator that adjusts the effective stroke of the pistons to increase or decrease displacement, thereby altering the pump's power absorption capacity. Over time, engine power output declines, and the swash-plate angle shifts, leading to a reduction in the pump's power absorption capacity; this significantly lowers the power absorbed by the hydraulic system.
CAT Comm Adapter3 478-0235 Diagnostics for Caterpillar
Symptoms typically include slower boom lifting/lowering, arm extension/retraction, upper structure slewing, and travel speed. In such cases, the initial course of action should be to adjust the main pump regulator rather than performing a major engine overhaul. Since the pump's initial power absorption does not match the engine's maximum output—leaving a margin—and the pump does not operate at its limit initially, adjusting the regulator allows the pump's power absorption capacity to increase. This compensates for the decline in the pump's own absorption capacity as well as the shortfall in absorbed power caused by the drop in engine output. Such adjustments ensure that the power absorbed by the hydraulic system remains at or near normal operating levels, thereby maintaining the excavator's proper functionality. The main pump regulator on a CAT excavator typically features three adjustment screws: one for negative flow control pressure, one for power variation pressure, and one for the maximum swashplate angle. To avoid adjustments that might cancel each other out, one should never blindly turn these screws without understanding the relationship between the adjustment direction and the resulting change in power. The standard procedure is to adjust one screw at a time; once the relationship between its adjustment direction and the power change is determined, return that screw to its original position. Follow the same method to identify the power-change relationships for the other two screws. Finally, adjust all three screws in the direction that increases power output, thereby enhancing the hydraulic system's power absorption capacity. Practical experience shows that a CAT excavator adjusted in this manner can continue to operate reliably for another year; by the time the engine requires a major overhaul, the machine may
Caterpillar 18 Digits Factory Password Calculator One-Time Calculate Service
have logged over 20,000 operating hours, representing significant economic value. It should be noted, however, that this type of main pump regulator generally allows for only one such adjustment. If the hydraulic system subsequently experiences a noticeable drop in power, further adjustments usually yield poor results, indicating that a major engine overhaul is required.
