I'm not sure if you meant to add a attachment but here is how a trolley works.
A trolley is a small car that is moved along a set of tracks by pulling on a rope or cable. The trolley consists of a simple frame that is mounted on wheels, and it may be powered by an electric motor or a simple hand-crank. The wheels are designed to run along the track smoothly, and the trolley is guided by the shape of the rails. The cable that powers the trolley is typically supported by a system of pulleys and gears, which help to distribute the force evenly between the trolley and the cable. This allows the trolley to move smoothly and quickly along the track, without slipping or losing traction. The power source for the trolley may be located at one end of the track, and the trolley operator pulls or releases the cable to control the speed and direction of the trolley. Alternatively, the trolley may be powered by an electric motor located on the trolley itself, which can be controlled using a simple switch or remote control. Regardless of the power source, the trolley is a simple and effective way to move people or goods from one place to another along a fixed path.