Series 4000 and 5000 hydraulic piston accumulators from Parker Hannifin Corp., Hydraulic Accumulator Div., Rockford, Ill., are featured in a 36-page catalog. Series 4000 piston accumulators for mobile-equipment applications have a 4,000-psi operating pressure and 2 to 6-in. bores with over 30 standard capacities. The 5000 piston accumulators, which are designed for rugged industrial applications, come in 2 to 9-in. bores with more than 30 standard capacities. Both series feature patented V-O-ring piston seals, serviceable threaded-end construction, and six standard seal options to handle a variety of fluids and temperatures.