As shown in figure sliding plates can slide over fixed plates. Stationary plate is simply supported horizontaly on sliding plates. Lubrication is provided at contact surfaces of stationary plate and sliding plates. Weight or load or force (mg) is applied at center of stationary plate. This load is equally devided and applied on each sliding plate in vertical downward direction (mg/2). This mg/2 cos(alpha) helps sliding plate to slide in nearly downward direction.

Force is stationary and it can help to slide the sliding paltes.