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A Pitman arm is a shaft that translates rotary or angular movement into linear movement, or vice versa. Pitman arms are commonly found in water pumping windmills, automotive
A Pitman arm is a shaft that translates rotary or angular movement into linear movement, or vice versa. Pitman arms are commonly found in water pumping windmills, automotive steering
Steering is the control of the direction of motion or the components that enable its control. Steering is achieved through various arrangements, among them ailerons for airplanes, rudders for boats, cylic tilting of rotors for helicopters, ...
systems, and sewing machines.
In windmills, the Pitman arm connects the driving gear to the pumping arm. It translates the rotary power from the wind blades to the up-and-down motion of the pumping arm.
In automotive or truck steering systems, the Pitman arm acts as a linkage attached to the steering box (see recirculating ball) sector shaft, it converts the angular motion
In physics, motion is when an object changes its position with respect to a reference point in a given time. Motion is mathematically described in terms of displacement, distance, velocity, acceleration, speed, and frame of reference to an o ...
of the sector shaft into the linear
In mathematics, the term ''linear'' is used in two distinct senses for two different properties:
* linearity of a '' function'' (or '' mapping'');
* linearity of a '' polynomial''.
An example of a linear function is the function defined by f(x) ...
motion needed to steer the wheel
A wheel is a rotating component (typically circular in shape) that is intended to turn on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the wheel and axle which is one of the Simple machine, six simple machin ...
s. The arm is supported by the sector shaft and supports the drag link or center link with a ball joint. It transmits the motion it receives from the steering box into the drag (or center) link, causing it to move left or right to turn the wheels in the appropriate direction. The idler arm is attached between the opposite side of the center link from the Pitman arm and the vehicle's frame to hold the center or drag link at the proper height.
"Pitman arm" can also refer to a component in a treadle sewing machine that connects the foot pedal to the crankshaft of the lower flywheel. In this case, the Pitman arm works similarly to a connecting rod in an engine in which the up and down force applied at one end of the arm translates to pushing and pulling alternately on the eccentric part of the crankshaft to achieve continuous rotation of the crankshaft and flywheel. The bearing connecting the Pitman arm to the crankshaft is known as the Pitman bearing. Early Pitman arms (up until around 1905) were made of wood, whereas later Pitman arms were made of steel. Wooden Pitman arms usually employed a simple wooden bushing around a steel shaft at both ends. The later steel Pitman arms usually used a ball joint at the lower pivot point and a ball bearing for the Pitman bearing at the top.
See also
*List of auto parts
This is a list of auto parts, which are manufactured components of automobiles. This list reflects both fossil-fueled cars (using internal combustion engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the c ...
References
Automotive steering technologies {{Automotive-part-stub