Dow Hydraulic Systems, formerly Dow Precision Hydraulics, was founded in 1967 as a honing service. Over 40 years later we have since become an industry leader in the manufacturing and assembly of servo valves and sub-assemblies for the aerospace and industrial markets.

We specialize in; precision honing, precision OD grinding, internal and external lapping (up to 1.500 inch in diameter) with the ability to maintain straightness, roundness and cylindricity of .000020 (twenty millionths) of an inch. We can consistently maintain surface finishes of 4 microns and match fit sleeves and spools to tolerances of ±.000010 of an inch resulting in higher quality and longer lasting hydraulic valves.

Our Hydraulic Test department specializes in flow grinding and is equipped with state of the art TV Trim Grinding machines as well as skydrol and red oil testing capabilities.

With our expanding assembly department, we are ready to engage new challenges and welcome the opportunity to explore the possibility of serving your needs in this area. Feel free to explore your area of interest whether it be in manufacturing, hone, lapping, testing, or assembly. Thanks for visiting!


Dow Hydraulic Systems
1835 Wright Street
La Verne, CA 91750
Tel: 909-596-6602
Fax: 909-596-6605

2895 Metropolitan Place
Pomona, CA 91767
Fax: 909-596-0683