Frequently when designing simple hydraulic circuits that utilize low-cost solutions, system designers will often use fixed displacement pumps. One challenge associated with the use of fixed displacement pumps can be the constant flow of hydraulic oil while the machine is running, even when the flow is not needed at any of the hydraulic functions. Similarly, simple low-cost circuits frequently do not require the multi-functionality of high-cost sectional valves, thus keeping these circuits lower cost due to the less complex nature of the product used.
When a hydraulic circuit does not require or cannot have flow to two or more functions at the same time, 3-way, 2-position spool-type solenoid valves can be very useful. When these valves are used as a selector, primarily in circuits where the system designer may want to divert flow from one leg of a circuit to another, several 3-way, 2-position valves are a cost-effective alternative while emulating a traditional directional spool valve in a customizable manifold setup. Similarly, these valves can be used as a “dump” valve when a circuit does not require flow but is being driven by a fixed displacement pump running continuously.
Parker 3-way, 2-position spool-type solenoid valves can be used in a variety of applications, machinery, and market segments that require switching or diverting function. The design of 3-way, 2-position valves generally include a three-ported design that would allow flow paths in several different configurations while only connecting two ports in any one position.
In the image below, you will find an example circuit for a blower/brush application for a piece of construction machinery. The 3-way, 2-position spool-type solenoid valve, which is circled in red, is being used as a diverter to solely supply flow to one function at a time. Function one is a lift/lower, up and down motion and function two is a tilt/swivel, side-to-side motion.
Note that all solenoid valves with this design have flow restrictions with pressure drop associated across the valve, so continuous flow will result in heat generation after a given period of time. Additionally, 3-way, 2-position solenoid valves that use a spool-type design will have a higher leakage rate than those with a poppet design, and thus would not be recommended for use in load-holding applications.
Parker Hydraulic Cartridge System Division’s valves allow full rated pressure at all 3 ports with varying flow rates in industry common cavity sizes. Valve sizes of -8, -10, and -16 are available with flow ranging up to 15 GPM and pressures as high as 5,000 PSI.
Parker’s 3-way, 2 position valves are available for purchase on parker.com. Simply add products to your cart for shipment within two days for in-stock items.
Article contributed by Stephen Brunton, product manager, Hydraulic Cartridge Systems Division.