This example shows a motor driven power window system. A DC motor drives the power window mechanism via a self-locking worm gear with the ratio 1 : 50. The power window mechanism consists of driving pulley DP, four supporting rollers R1, R2, R3, and R4, and two glass clamps, GC1 and GC2. The window itself is attached to the glass clamps and is lifted up as the clamps move up. The glass clamps, in turn, are attached to the rope in such a way that both clamps are moved at the same velocity, keeping the window level. The driving pulley is simulated with the Rope Drum block, while the supporting rollers are modeled with Belt Drive Pulley blocks. The rope is put between the pulley and rollers as shown in the mechanism schematic. Tensioners are added between the pulleys as necessary, and are simulated using a damper and preloaded spring. The window is represented by the Window load subsystem and the Lever block whose ports A and B correspond to the attachment points with the glass clamps. Two rotational damper blocks are attached to ports A and B to simulate friction in the window guideways. When modeling systems using pulleys and rope drums, it is important to be mindful of the tension and force transmission of the belts and ropes throughout the system. In reality, slack ropes and belts cannot transmit force, and the results should be interpreted with this in mind.