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What is the outside diameter of a gear?

To Find Equation
Gear Ratio mG = NG / Np
Number of Teeth N = P D N = ( π D ) / p
Outside Diameter (Full Depth Teeth) DO = ( N + 2 ) / P DO = [ ( N + 2 ) p ] / π
Outside Diameter (American Standard Stub Teeth) DO = ( N + 1.6 ) / P DO = [ ( N + 1.6 ) p ] / π

What is base circle diameter in gears?

Outside Diameter (O.D.) is the diameter of a circle around the outer surface, or tops of the gear teeth. Root Diameter (R.D.) is the diameter of a circle around the bottom (root) of the gear tooth spaces. Base Circle is the circle from which the involute portion of the tooth profile is generated.

What is reference diameter in gear?

The standard reference pitch diameter is the diameter of the standard pitch circle. The pitch diameters of two gears may be used to calculate the gear ratio in the same way the number of teeth is used.

What is addendum and Dedendum in gear?

Addendum: The radial distance between the pitch circle and the addendum circle. Dedendum: The radial distance between the pitch circle and the root circle. Backlash: The difference between the circle thickness of one gear and the tooth space of the mating gear.

What is DP in gear?

DP: Stands for “Diametral Pitch”. It’s a ratio equal to the number of gear teeth per inch of printing diameter.

What is a diametral pitch?

The diametral pitch of a gear is the number of teeth in the gear for each inch of pitch diameter. Therefore, the diametral pitch determines the size of the gear tooth.

What is the formula for diametral pitch?

This value is: z = d/m. Module (m). Ratio between the pitch circle in millimeters and the number of teeth. Anglo-Saxon countries use the “Diametral Pitch” instead, which is inversely proportional to the module.

How do you determine the pitch of a gear?

Divide the number of teeth on the gear by this measurement. For example, if the gear has 28 teeth: 28 / 6 = 4.67. Round this figure to the nearest whole number: 4.67 is approximately 5, so the gear has a pitch of 5.

What is the difference between circular pitch and diametral pitch?

Diametral Pitch is the Number of Teeth Per Inch of the Pitch Diameter. The width of a tooth and a space, measured on the pitch circle. That is, the product of the diametral pitch and the circular pitch equals . Module m: Pitch diameter divided by number of teeth.

Do gears need the same pitch?

Gears must have the same pitch or module in order to work together. To measure the pressure angle and pitch or module of a gear, use a Gear Tooth Pitch Identifier. If you don’t have a gear tooth pitch identifier, you can estimate a spur gear’s pitch or module.

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.

What is Z in gear ratio?

It is the ratio of the reference diameter of the gear divided by the number of teeth. Thus m = d/z (Module = Reference diameter/Number of teeth) The mutual relation between the module and the reference diameter, etc.

How do you determine gear size?

The gear ratio is calculated by dividing the output speed by the input speed (i= Ws/ We) or by dividing the number of teeth of the driving gear by the number of teeth of the driven gear (i= Ze/ Zs).

What is a gear pitch?

The pitch of a gear is defined as the distance between two identical points on two adjacent gear teeth. Ideally, it is measured at the pitch line, labeled in Figure 1 as the reference line.

What is the pitch diameter?

Pitch diameter is the distance from the pitchline to the corresponding pitchline located 180 degrees around. All threads have a pitch diameter whether they are a straight or tapered thread. However, some threads’ pitch diameters are actually measured via their crest diameter (diameter from crest to crest) instead.

What is flange diameter?

For a regular pipe flange, first measure the flange’s outside diameter (O.D.). This can be accomplished by measuring from the outside edge of the flange to the opposite outer edge. Bolt circle diameter is the measure from the center of a bolt hole to the center of the hole on the opposite side.

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

Gear calculations: Pitch − circle diameter = module × no . of teeth = 12 × 25 = 300 mm.

What is the difference between pitch diameter and diametral pitch?

DIAMETRAL PITCH (P) is the ratio of the number of teeth to the pitch diameter. FACE WIDTH (F) is the length of the teeth in an axial plane. FILLET RADIUS (rf) is the radius of the fillet curve at the base of the gear tooth. When two gears run together, the one with the larger number of teeth is called the gear.

What is normal pitch in helical gear?

Normal pitch:- The normal pitch of a helical gear is the pitch of the tool used to cut the teeth. It is measured in a plane perpendicular to the direction of the teeth. 4.

How do you find the root diameter of a gear?

Root Diameter (df) is the diameter of the root circle; its value is: df = m (z – 2.5) or df = de – 2h. Center Distance (dc) is the distance between the shafts of the gear and the pinion; its value is: dc = (D + d) / 2, where “D” corresponds to the pitch diameter of the gear and “d” to the pitch diameter of the pinion.

How do you identify a gear module?


  1. Count how many teeth a sample spur gear has z =
  2. Measure its tip diameter da =
  3. Estimate an approximation of its module, assuming that it has an unshifted standard full depth tooth, using the equation:
  4. Measure the span measurement of k and the span number of teeth.
  5. This difference represents pb = πm cos α

How do you find the pitch of a helical gear?

In the normal system, the calculation of a profile shifted helical gear, the working pitch diameter dw and working pressure angle αwt in the axial system is done per Equations (6-10). That is because meshing of the helical gears in the axial direction is just like spur gears and the calculation is similar.

How do you calculate the number of teeth on a helical gear?

How is helical gear ratio calculated?

To calculate the gear ratio: Divide the number of driven gear teeth by the number of drive gear teeth. In our example, it’s 28/21 or 4 : 3. This gear ratio shows that the smaller driver gear must turn 1,3 times to get the larger driven gear to make one complete turn.