M - 250 yh surface grinding machine with hydraulic surface grinding machine is on the basis of M250 manual surface grinding machine, the workbench for manual vertical movement of the hydraulic system of the hydraulic system is a set of quantitative pump motor group, 18 l/min pump maximum flow, motor power 1.5 KW, the work of the pump pressure can reach 3 mpa, system pressure relief valve main mechanical valve adjustment system for grinding machine is special valve, divided into two parts, mechanical commutation control, throttle speed regulation control throttle control part and unloading function, which can realize the workbench's start-stop this valve has buffer adjustment function of the machine tool is easy to operateFlexible, reliable, no vibration accuracy, stable, good thermal stability, low noise, convenient maintenance, etc