Rack and pinion
A rack and pinion is a pair of gears that convert
rotational motion into linear motion. The circular pinion engages teeth
on a flat bar truck parts
- the rack. Rotational motion applied to the pinion will cause the rack
to move to the side, up to the limit of its travel. Example, in a rack
railway, the rotation of a pinion mounted on a locomotive or a railcar
engages a rack between the rails and pulls a train along a steep slope.
The rack and pinion arrangement is commonly found
in the steering mechanism of cars or other wheeled, steered vehicles.
This arrangement provides a lesser mechanical advantage than other
mechanisms such as recalculating ball, but much less backlash and
greater feedback, or steering "feel".
The use of a variable rack was invented by Arthur E
Bishop, thus as to improve vehicle response and
steering "feel" on-centre, and that has been fitted to many new
vehicles, after he created a hot forging process to manufacture the
racks, thus eliminating any subsequent need to machine the form of the
gear teeth.
A generating rack is a rack outline used to
indicate tooth details and dimensions for the design of a generating
tool.For every pair of conjugate in volute profile,
there is a basic rack. This basic rack is the profile of the conjugate
gear of infinite pitch radius.
