Viscosity-temperature compensator for hydraulic systems

摘要

A hydraulic control system for a downhole sidewall coring tool having first and second power hydraulic systems in which changes in pressure drop in a portion of the first hydraulic system adjusts a control valve to change the pressure in a part of the second hydraulic system. Means are provided to adjust the operation of the control valve as a function of viscosity change in the hydraulic fluid caused by change in ambient temperature.