favoured design where the torque is biased to the front wheels to give car-like handling, or where the maker wishes to produce both four-wheel drive and front-wheel drive cars with many shared components. Research and development The automotive industry also uses drive shafts at testing plants. At an engine test stand a drive shaft is used to transfer a certain speed or torque from the internal combustion engine to a dynamometer. A "shaft guard" is used at a shaft connection to protect against contact with the drive shaft and for detection of a shaft failure. At a transmission test stand a drive shaft connects the prime mover with the transmission. Symptoms of a bad drive shaft An automotive drive shaft can typically last about 120,000 kilometres. However, if the vehicle experiencing any of the signs below, drivers should get it checked as soon as possible at a mechanic. Clicking or squeaking noise: Driver can either hear a clicking, squeaking, or grinding noises coming from underneath the vehicle when driving. While all of these could be because of the faulty bearings or bushings that make the drive shaft can't function properly, and start making a lot of strange noises. Clunking sounds: Driver can hear the noises especially when turning the vehicle, accelerating or even putting it into reverse. Vibration: An early and common symptom of a failing drive shaft is an intense vibration coming from underneath the vehicle. Worn out couplings, u-joints, or bearings cause excessive drive shaft vibration. Turning problems: Problems with turning the vehicle, both during slow and high-speed drives, is another significant sign of a bad drive shaft. Cardan shaft park brakes A cardan shaft park brake works on the drive shaft rather than the wheels. These brakes are commonly used on small trucks. This type of brake is prone to failure and has led to incidents where the truck has run away on a slope, leading to safety alerts being issued. Heavy vehicles that have this type of park brake usually have a ratchet handle similar to a car's hand brake or parking brake, as opposed to an air brake button or lever. Risk factors for drivers include parking on a steep slope when heavily loaded, not applying the brake with enough force, changing the load or load balance while parked on a slope, or parking where one side of the vehicle is able to slip. Using