One risk of overloading the oil pump motor unit is the danger of excessive torque on the drive shaft. Torque is a circular force on an object. If the pump displacement / pressure remains constant, an increase in pressure / pump displacement will increase the torque on the shaft. Generally, in a given package size, a higher GPM pump will have a lower pressure rating than a lower GPM pump. Sometimes obtaining high speeds from actuators by switching on-site will cause the pump to overload. You may need a large pump.
Operating the oil pump motor set at too high a speed can result in loss of lubrication, leading to early failure. If the required delivery requires a high drive speed instead of the pump's rating, use a high displacement pump. Excessive speed also risks cavitation damage. Cavitation occurs where available fluid does not fill the existing space. It usually occurs at the pump's inlet when conditions are not sufficient to supply enough oil to keep the inlet submerged. Cavitation causes metal corrosion in the inlet and the hydraulic oil deteriorates quickly. If there is too much resistance in the inlet line, cavitation can occur if the oil level in the fuel tank is lower than the air intake, or if the oil viscosity is too high. This can also happen if there is a vacuum or even a slight positive pressure at the inlet. A severely cavitation pump exploded with oil bubbles in the interstices. One way that a tube pump does not cause cavitation is to check the inlet with a vacuum gauge.
To prevent cavitation, use the correct length of inlet tubing and small bends to keep the inlet clean and free of obstacles. Another method is to charge the inlet. The simple way is to fill the water tank by placing it above the inlet of the pump. If this is not possible and you cannot create good inlet conditions, use a pressurized reservoir. You can also use pumps to maintain oil supply at low pressure inlets. You can use a centrifugal pump, but it is common to use a positive displacement gear pump with a pressure relief valve set to maintain the required inflation pressure.