A laboratory simulation for stick-slip phenomena on the hydraulic cylinder of a construction machine

Stick-slip properties between steel and the glass fiber-reinforced nylon employed in the hydraulic cylinder of a construction machine were studied with a reciprocating tribometer as a laboratory simulator. A stick-slip evaluation method was established by introducing the running-in operation under certain operating conditions. Through studying the effect of sliding speed, the normal load and the viscosity, it was found that the sliding surfaces were operated in the mixed lubrication regime, where some friction modifiers were effective for elimination of stick-slip. Surface observation and surface analysis of the specimens after the tests indicated that stick-slip was mainly caused by an increase in the static friction coefficient due to transfer of iron oxide on to the seal surface from the steel surface. Subsequently, an attempt was made to correlate the results by the simulation test results for the hydraulic oil with those obtained by the hydraulic cylinder test.