Machine Design

Valve coils handle abuse

A new valve coil designed for harsh off-highway environments is said to lengthen machine service intervals and help prevent unscheduled downtime.

Valve coils for off-highway duty are encapsulated in plastic and protected by a metal frame.

The coils, developed by Sauer-Danfoss, Ames, Iowa (, tolerate temperature and voltage extremes and withstand powerspray wash down, water submersion, and exposure to mud and snow.

The unit features a protective plastic layer surrounded by a solid metal frame. A special molding technique keeps moisture out of the electrical components during the encapsulation process, helping ensure trouble-free operation and making O-ring seals unnecessary. The IP69K-rated coil has passed a range of tests, including highpressure spray, shock and vibration, thermal shock and dunk, salt fog, and a combined temperature, humidity, and voltage test.

Ambient temperature range is 40 to 71°C in continuous operation, and the coil handles input voltage variations from 75 to 133% of nominal with no ill effects. The compact coil is reportedly smaller than many competing products, letting cartridge valves mount closer together in vehicle circuit blocks. This leaves more space for other components and adds design flexibility.

Electrical connectors include Deutsch DT04-2P, Metri-Pak 150 Series Type 1, and 18-in. lead wires, color coded for easy voltage identification. Integral diodes are optional.

Applications include asphalt machinery, agricultural equipment with chemical and power-wash exposure, snowplows, and saltspreading machines.

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