A floor jack is a hydraulically-operated portable jack, mounted on wheels, which is used to raise a vehicle a short distance off the ground, especially when only part of the vehicle needs to be raised. The lifting pad on the jack is positioned under the chassis of the vehicle, at the manufacturer's recommended lift points, and the jack handle worked with a pumping action. This forces fluid into the hydraulic cylinder, which extends, driving the jack lift pad upwards and thereby lifting the vehicle. Note that floor jacks are not intended to support vehicles while people are working under them. Jack stands are essential for this purpose.