What are the primary causes of cavitation in a hydraulic pump?

The primary causes of cavitation in a hydraulic pump are insufficient fluid supply to the pump inlet and excessive restriction in the pump inlet line, both of which lead to a drop in pressure below the fluid's vapor pressure. Cavitation is the formation and subsequent collapse of vapor bubbles within a liquid. In a hydraulic pump, it occurs when the pressure at the pump inlet drops below the vapor pressure of the hydraulic fluid at that temperature. This causes the fluid to vaporize, forming tiny bubbles. As these bubbles travel through the pump to areas of higher pressure, they implode violently. These implosions generate intense localized pressures and temperatures that can damage the pump's internal components. Insufficient fluid supply can be caused by a low fluid level in the hydraulic reservoir, a clogged reservoir outlet strainer, or a kinked or collapsed inlet line. These conditions restrict the flow of fluid to the pump, causing the pressure at the pump inlet to drop. Excessive restriction in the pump inlet line can be caused by a clogged inlet filter, an undersized inlet line, or excessive length or bends in the inlet line. These restrictions impede the flow of fluid to the pump, creating a pressure drop. Other factors that can contribute to cavitation include high fluid temperature, which increases the fluid's vapor pressure, and operating the pump at excessive speeds, which increases the demand for fluid and can exacerbate any supply restrictions. The symptoms of cavitation include a rattling or knocking noise from the pump, reduced pump output, and premature pump wear. Preventing cavitation requires ensuring an adequate fluid supply to the pump inlet, minimizing restrictions in the inlet line, maintaining proper fluid temperature, and avoiding over-speeding the pump.