Quench oil cooler

A quench oil cooler is a heat exchanger that holds the working temperature of hydraulic and circulating oils down by transferring their heat to cooling water or air. In a steering-gear or deck-machinery HPU it cools the oil leaving the pumps and actuators so the oil keeps its viscosity and the seals and additive package do not break down at sustained high load. Built as a shell-and-tube or plate cooler in the return or case-drain line, it rejects heat to the low-temperature fresh-water cooling loop, with a thermostatic bypass holding the oil in its design band.