Abstract：The parking brake is one of the essential units embedded in track driving motor for forward and backward motion of an excavator. It is composed of multi-friction discs. When the hydraulic motor stops, the multi-friction discs closely stick to the facing discs by acting of multi-spring forces. So, the friction forces generate the braking force by compressing the cylinder barrel of hydraulic motor. In this study, we combined the multi-friction discs to two kinds of spring which have different spring force. and the maximum torque measured at the rotational starting point of hydraulic motor through gradually increasing the rotational torque of load side hydraulic motor by use of 1 and 2 sheets of friction plates. And, under this experimental condition, the maximum coefficient of static friction and the characteristics of paper friction sheet were analyzed. The obtained experimental results will be applied to the design of parking brake system for producing large size excavator in the 85-ton weight class.Y. B. Lee(corresponding author) :

Key Words：Excavator(굴삭기), Parking Brake(주차 브레이크), Coefficient of Friction(마찰 계수), Multi-friction Discs(다중 마찰 판), Paper Friction Material(종이 마찰재)Abstract：The parking brake embedded in track driving motor for driving an excavator is composed of wet type multi-friction discs. This type parking brake can be designed more compact because the combination of some sheets of friction discs generate great braking power, and also it has good braking characteristic and long life time because it works in the oil. In this study, we analyzed torque characteristic of the parking brake through simulations and performed experiments by use of 3-kinds of paper friction sheet manufactured by different pressing methods. And, we compared the maximum static friction coefficient and torque characteristic with the simulation results and confirmed the optimal manufacturing process through this result.