What is the pitch circle of a gear?

What is the pitch circle of a gear?

Pitch circle: The circle, the radius of which is equal to the distance from the center of the gear to the pitch point. This is where the gear’s speed is measured. Pitch diameter: Diameter of the pitch circle. Pitch point: The point of tangency of the pitch circles of a pair of mating gears.

What is the connection between circular pitch and pitch diameter?

We know that the velocity ratio of a pair of gears is the inverse proportion of the diameters of their pitch circle, and the diameter of the pitch circle equals to the number of teeth divided by the diametral pitch.

How do you measure the pitch circle diameter of a gear?

The pitch circle diameter is d = zm (where z = number of teeth, m = module). The pitch circle diameters are important numbers in locating the shafts of two mating gears. The center distance of two meshing gears is expressed as the sum of the pitch circle radii of the two gears.

Is the number of teeth on the gear per unit of the pitch circle diameter?

Explanation: Diametral pitch is the number of teeth per unit length of the pitch circle diameter. It is used to classify different types and sizes of gears. It is a function of the pitch circle.

What is the formula of circular pitch?

Circular pitch = π × module = π × 12 = 37.68 mm.

What is meant by pitch circle diameter?

The Pitch Circle Diameter (PCD) is the diameter of the circle which passes through the centre of all the studs, wheel bolts or wheel rim holes. The easiest way calculate the PCD is as follows: 1) Measure the distance ‘S’ between two adjacent studs from the centre of each hole.

What is DP in gear?

Diametral Pitch (DP) A ratio equal to the number of teeth on a gear per inch of diameter.

How are reference pitch circles related to involute gears?

As already explained in detail in the article Construction and design of involute gears, the standard reference pitch circles of gears are specially defined circles to which the circular pitch is related.

What happens to pitch circles when center distance is changed?

If the center distance is changed, the inclination of the line of action (i.e. the pressure angle) and thus the position of the pitch point also changes. This also changes the operating pitch circles. The operating pitch diameters increase with increasing center distance.

How is the root circle of a gear tooth calculated?

Thus the root circle diameter is D – 2.5m. The involute is calculated in a standard way and looks like the unwinding of a string from a circle, the base circle: The gear tooth is then described by the intersection of the involute with the root diameter (the bottom of the tooth) and the outer diameter (the top of the tooth).

Why are the teeth of an involute gears a straight line?

The points of contact of two meshing tooth flanks describe a straight line for involute gears (line of action or line of engagement). Due to the special design of the tooth shape of an involute gear (rolling a straight line on a circle), the intersection of two involutes rolling off each other describes a straight line.