Question 405General Subjects - Assistant Engineer

The correct answer is B) the pump to operate sluggishly. Excessive lost motion in the valve mechanism of a duplex reciprocating pump will cause the pump to operate sluggishly. This is because the lost motion in the valve mechanism reduces the efficiency of the pump's operation, as the valves may not open and close at the optimal times during the pump's stroke. This results in the pump not being able to draw in and discharge the fluid as effectively, causing the overall pump operation to become sluggish. The other options are incorrect because: A) cushioning valves wear is not a direct consequence of lost motion in the valve mechanism; C) the pump will not short stroke continuously at both ends of the stroke for both cylinders; and D) the pistons will not stop in mid-stroke due to lost motion in the valve mechanism.