A trolley jack is a type of hydraulic jack used to lift heavy vehicles, such as cars and trucks, for maintenance or repair. It features a wheeled frame that allows for easy maneuverability under the vehicle. The jack operates by using hydraulic pressure to raise the lifting arm, which supports the vehicle once elevated. Typically, a trolley jack has a low profile, making it suitable for vehicles with limited ground clearance. It is commonly used in automotive workshops and by DIY enthusiasts. Safety features, such as a locking mechanism, help prevent accidental lowering of the vehicle while work is being done.