A Panhard rod is a component of a car

Automobile

An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...

 suspension

Suspension (vehicle)

Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose — contributing to the car's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants...

 system that provides lateral location of the axle

Axle

An axle is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to its surroundings, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle...

. Originally invented by the Panhard

Panhard

Panhard is currently a French manufacturer of light tactical and military vehicles. Its current incarnation was formed by the acquisition of Panhard by Auverland in 2005. Panhard had been under Citroën ownership, then PSA , for 40 years...

 automobile company of France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 in the early twentieth century, this device has been widely used ever since.

While the purpose of the suspension of an automobile is to allow the wheels to move vertically with respect to the body, it is undesirable to allow them to move forward and backwards (longitudinally), or side to side (laterally). The Panhard rod is designed to prevent lateral movement. It is a simple device, consisting of a rigid bar running sideways in the same plane as the axle, connecting one end of the axle to the car body or chassis

Chassis

A chassis consists of an internal framework that supports a man-made object. It is analogous to an animal's skeleton. An example of a chassis is the underpart of a motor vehicle, consisting of the frame with the wheels and machinery.- Vehicles :In the case of vehicles, the term chassis means the...

 on the opposite side of the vehicle. The bar is attached on either end with pivots that permit it to swivel upwards and downwards only, so that the axle is allowed to move in the vertical plane only. This does not effectively locate the axle longitudinally, therefore it is usually used in conjunction with trailing arm

Trailing arm

thumb|220px|Trailing arm rear suspension of [[Front-engine, front-wheel drive layout|FF]] carsA trailing-arm suspension is an automobile suspension design in which one or more arms are connected between the axle and the chassis. It is usually used on rear axles...

s which stabilize the axle in the longitudinal direction. This arrangement is not usually used with a leaf spring

Leaf spring

Originally called laminated or carriage spring, a leaf spring is a simple form of spring, commonly used for the suspension in wheeled vehicles...

  suspension, where the springs themselves supply enough lateral rigidity, but only with coil spring suspensions.

The advantage of the Panhard rod is its simplicity. Its major disadvantage is that the axle must necessarily move in an arc relative to the body, with the radius equal to the length of the Panhard rod. If the rod is too short, there will be excessive sideways movement between the axle and the body at the ends of the spring travel. Therefore, the Panhard rod is less desirable on smaller cars than larger ones. A suspension design that is similar but dramatically reduces the sideways component of the axle's vertical travel is Watt's linkage

Watt's linkage

Watt's linkage is a type of mechanical linkage invented by James Watt in which the central moving point of the linkage is constrained to travel on an approximation to a straight line...

.

Some vehicles including Land Rovers with live axle

Live axle

A live axle, sometimes called a solid axle, is a type of beam axle suspension system that uses the driveshafts that transmit power to the wheels to connect the wheels laterally so that they move together as a unit....

suspensions use a Panhard rod as a component of the front suspension where Watt's linkage is not an option.