What does severe kickback of the emergency hydraulic hand pump handle during the intake stroke indicate?

Severe kickback of the emergency hydraulic hand pump handle during the intake stroke indicates that the hand pump outlet check valve is sticking open. When the outlet check valve does not close properly during the pumping cycle, it allows hydraulic fluid to flow back into the pump, creating a pressure imbalance. As a result, when the handle is pulled during the intake stroke, the pump cannot properly create a vacuum, leading to a significant kickback force which is felt at the handle. This condition can compromise the effectiveness of the hydraulic system, making it challenging to operate the pump efficiently.

A damaged outlet check valve would likely lead to other symptoms, such as fluid leakage or failure to build pressure, rather than a kickback during the intake stroke. Similarly, hydraulic fluid leakage typically produces different indicator signs such as wet or damp areas around the pump or reduced operational pressure, while a clogged pump would not solely cause kickback; instead, it could lead to an overall reduction in fluid flow and performance. Understanding the function of the check valve and its role in maintaining pressure in the system is crucial for diagnosing this issue accurately.