This is one of the most common applications of an accumulator. In this application, the purpose of the accumulator is to store the oil delivered by the pump during the work cycle. The accumulator then releases the stored oil on demand, to complete the cycle, thereby serving as a secondary power source to assist the pump. In such a system where intermittent operations are performed, the use of an accumulator results in reduced pump capacity.
Figure 7.22 outlines this application with the help of symbols.
In this application, a four-way valve is used in conjunction with an accumulator. When the four-way valve is manually actuated, oil flows from the accumulator to the blank end of the cylinder. This extends the piston until the end of the stroke. When the cylinder is in a fully extended position, the pump charges the accumulator. The four-way valve is then de-activated to retract the cylinder. Oil flows from the pump and the accumulator to retract the cylinder rapidly. This is how an accumulator can be used as an auxiliary power source.