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New valve solenoids push reliability up, costs down

Caterpillar Inc. developed dependable new solenoids for operating hydraulic valves on heavy-duty equipment. The solenoids are an encapsulated design using Rynite® PET resin for both the coil bobbin and the outer encapsulating shell, which has an integral electrical receptacle. Caterpillar produces the solenoids in two bore sizes, 0.5 and 0.75 in. (13 and 19 mm). The smaller solenoid draws up to 1 or 2 A, depending on the design, while the larger draws up to 2 A. Operating forces are up to 60 N (13.5 lbf). Caterpillar uses these units as both replacement parts for existing valves, original equipment for new valves, and also offers them to other manufacturers who need rugged solenoids.

DuPont provided crucial assistance to Caterpillar in material selection, part and mold design, and rocess optimization. Rynite® was chosen for its durability and resistance to moisture, and serves for both the encapsulation and the bobbin.

The solenoids made with Rynite® offer durability and meet demanding requirements for resistance to heat, thermal shock, vibration, moisture penetration, fuel, and lubricants. Caterpillar rates solenoids for service at ambient temperatures from -40 to +121° C (-40 to +250° F).

The solenoids are designed to keep water out and have better resistance to moisture penetration than previous designs. This is achieved with a proprietary bobbin design, careful control of molding process conditions during encapsulation, and astute receptacle design.

With the efficiency and versatility of molding with Rynite® PET, the solenoids cost less than components previously manufactured. In addition, integration of the electrical receptacle into the encapsulation shell saves the cost of an additional part.

To learn more about the uses of Rynite® or other DuPont products and solutions, please contact us.