Machine Elements:

Rack & Pinion

Carmen

Definition

- A single gear, the pinion, meshes with a sliding toothed rack. Of two mating gears, the one with the smaller number of teeth is called the pinion. The rack is a gear with teeth spaced along a straight line, and suitable for straight-line motion. This combination converts rotary motion to back and forth motion.

• Rack and Pinion

Formula

ROTATION results when an unbalanced torque acts on a body producing an angular acceleration. The torque to accelerate is the product of the body's moment of inertia about its axis of rotation (J) and the angular acceleration (a).

Rotation = J a

Source-http://www.globalspec.com/Oriental MotorUSA/ref/Sizing_Formulas

Formulas (Cont.) The steering ratio is the ratio of how far you turn the steering wheel to how far the wheels turn.

Example (car steering)If one complete revolution (360 degrees) of the steering wheel results in the wheels of the car turning 20 degrees, then the steering ratio is 360 divided by 20, or 18:1.

Everyday Applications

•Rack and pinion gears from

a household scale. •Rack and pinion from car’s steering column.

Source- http://auto.howstuff works.com/steering2.htm

A large gear wheel, called the ‘pinion’, is added to the center of the train and an extra track, that has teeth, called the ‘rack’ is added to the track. As the train approaches a steep hill or slope the gear is lowered to the track and it meshes with the ‘rack’. The train does not slip backwards but it is pulled up the steep slope.

A Practical ExampleSource-http://www.technology student.com/gears1/gears 4.htm

 

• As the handle is turned the table moves up and down the central pillar of the drill. This makes it easy to move the table and takes the minimum  of effort.                                                                  

Drilling Machine

Source- http://www.technology student.com/gears1/drlgear.htm