Which factor increases the braking effect in the braking system of the train cars?

The braking effect in the braking system of train cars is primarily influenced by the motion of the brake handle or pedal. When the train operator activates the brake handle or pedal, it directly engages the braking system, whether it involves air brakes, dynamic brakes, or other mechanisms. The movement of this control initiates the braking process, applying force to the brake pads or shoes against the wheels or tracks, thereby generating the friction needed to slow down or stop the train.

This specific action is pivotal because it determines the intensity and immediacy of the braking response. The quicker and more forcefully the brake handle is engaged, the more effective the braking will be, allowing for quicker deceleration and increased control over the train's speed in various situations. Hence, the motion of the brake handle or pedal directly correlates to the braking effect being applied to the train.

While factors such as the speed of the train and the load it is carrying can influence overall braking performance, they do not increase the braking effect itself in the way that the operator's control over the braking mechanism does. Similarly, the condition of the track can affect safety and traction but does not directly enhance the braking effect initiated by the operator’s actions.