Spur gear measurement

 Spur gear measurement

Pitch

 

Pitch is the distance from one gear tooth to the corresponding identical point on the next tooth, measured along the pitch circle. The ratio of the number of teeth to the gear’s size can be ascertained from this result.

Pitch Measurement Use

Pitch measurement is a catch-all term that can include circular pitch, module (for metric measurements), or most commonly, diametral pitch. These measurements are useful for finding replacement gears of the appropriate gear mesh.

Pitch Diameter

 

Pitch diameter is the diameter of a theoretical pitch circle around which the gear teeth are designed. 

Equation

  • Pitch diameter = number of teeth / diametral pitch

Pitch Diameter Measurement Use

Pitch diameter is the main reference measurement for gear size in gear calculations, and also helps find the number of teeth in a gear. Pitch circle affects the gear’s rotational speed and torque.

Pitch Circle (or circular pitch)

 

The pitch circle is centered on the gear axis and passes through the pitch point of each tooth. It's the primary basis for defining the gear geometry and tooth spacing.

Equation

  • Pitch circle = 3.14 / diametral pitch

Pitch Circle Measurement Use

Pitch circle is used to determine many important measurements including gear speed.

Number of Teeth

 

This is a simple measurement of the total number of teeth on the gear. It's a crucial parameter affecting the gear ratio and other gear characteristics.

Equation

  • Number of Teeth = pitch diameter  x  diametral pitch

Number of Teeth Measurement Use

Knowing the number of teeth on any given spur gear is essential for optimal pairing with other gears to form a properly functioning gear set with the appropriate gear ratios.

Gear Module

 

A measurement representing the size of the tooth in metric measurements. Like diametral pitch in imperial measurements, its result is the ratio of the pitch diameter to the number of teeth. 

Equation

  • Module = pitch diameter (mm) / number of teeth

Gear Module Measurement Use

Commonly used in metric gear design, the module measurement defines the size of a gear and guides designers toward mating gears that mesh appropriately.

Diametral Pitch

 

Diametral pitch measures the number of teeth per inch of the pitch diameter. 

Equation

  • Diametral Pitch = number of teeth / Pitch diameter 

Diametral Pitch Measurement Use

Diametral pitch is commonly used in imperial gear design to determine the number of teeth on any given sized gear. It’s also used in assessing gear strength and load capacity.

Outside Diameter

 

A gear’s outside diameter is measured around the gear on the top of the gear’s teeth as if they were connected in a circle. 

Equation

  • Outside Diameter = (# of teeth + 2)/diametral pitch
  • Outside Diameter = pitch diameter + (2 x addendum)

Center Distance

 

Center distance is measured as the distance between the centers of mating gears. 

Equation

  • Center Distance = (pitch diameter of Gear A + pitch diameter of Gear B)/2

Center Distance Measurement Use

This measurement is used to calculate testing diameter and backlash.

Addendum

 

A gear’s addendum is measured as the distance (or height) from the pitch diameter to the outside diameter of the tooth. 

Equation

  • Addendum = (outside diameter - pitch diameter)/2

Addendum Measurement Use

Typically equal to the module or diametral pitch, addendum is used to measure the size of the gear tooth and the distance it deviates from the pitch circle.

Dedendum

 

Dedendum is the distance (or height) from the pitch diameter to the gear tooth’s root.

Equation

  • Dedendum = (pitch diameter - root diameter)/2

Dedendum Measurement Use

Dedendum is typically 1.25 times the module for involute gears, used in conjunction with addendum measurements to establish the size of a tooth.

Whole Depth

 

Whole depth is the height of the gear’s tooth from the tip circle to the root circle. It is calculated as the sum of the addendum and dedendum.

Equation

  • Whole Depth = addendum + dedendum

Whole Depth Measurement Use

Whole depth is used to define the entire height of the gear tooth.

Pressure Angle

 

The pressure angle represents the angle between the tooth face and the common tangent to the pitch circle, radial line and the gear tooth profile.

Pressure Angle Measurement Use

Pressure angle measurements are required for determining the tooth profile and gear strength. The most common pressure angle is 20°. It’s critical that the pressure angle and pitch must match exactly for two gears to mesh properly.

Face Width

 

Face width is the width of the gear tooth along the gear face, or the axial length of a gear’s tooth.

Face Width Measurement Use

Face width affects the overall shape and size of a gear, which is a determining factor in bending and tooth surface strength. 

Backlash

 

Backlash is the amount of clearance space between the meshing teeth of a pair of gears. It is the lost motion that occurs when gear movement is reversed and contact is reestablished on the opposite side of the meshing gears.

Equation

Backlash Measurement Use

Gear designers use backlash determinations to select gear pairings that avoid slippage (because of too much backlash) or binding up (due to too little backlash). Gears developed with close attention paid to backlash and its calculations are the most efficient and usually the longest lasting. 

Contact Ratio

 

Contact ratio expresses the ratio of one-tooth meshing and two-tooth meshing in the rotational process of a pair of mated gears. 

Equation

  • Contact ratio = length of path of contact / base pitch

Contact Ratio Measurement Use

Contact ratio is useful in determining the likelihood of damage from excessive surface pressure. Typically, the greater the proportion of two-tooth meshing, the greater the strength of contact between the gears. 

Gear Ratio

 

Gear ratio is the relationship between the rotational rates of the two mating gears. It’s expressed as the number of teeth in the driven gear to the number of teeth in the driving gear. 

Equation

  • Gear ratio = number of teeth in driven gear / number of teeth in drive gear

Gear Ratio Measurement Use

Gear ratio measurements are used to create mechanical advantages like added torque or to change rotational speed and velocity between a pair of gears with differing numbers of teeth. 

Root diameter

 

The root diameter is the diameter of the root circle, which is an imaginary circle that runs through the root, or base of each gear tooth.

Equation

  • Root diameter = pitch diameter - 2 x dedendum 

Root Diameter Measurement Use

Root diameter measurements are useful in determining the gear tooth size of paired gears that will work appropriately in a set. 

Comments

Post a Comment

Popular posts from this blog

CMM (Coordinate Measuring Machine)

Image
  CMM (Coordinate Measuring Machine) Include Discontinued Series Product Lineup Handheld Probe Coordinate Measuring Machine  XM series The XM Series is a handheld coordinate measuring machine (CMM) that lets anyone easily measure 3D/GD&T features. The system is portable and shop-floor ready, so measurements can be taken in any location. The unit also automatically records measurement data and creates detailed inspection reports. The images showcases our latest XM-5000 model which allows high-accuracy measurement for palm-sized parts to large applications. Wide Area Coordinate Measuring Machine WM series The WM Series Coordinate Measuring Machine is a new handheld CMM designed accurate 3D and GD&T measurements over a large 15m (49 ft) area. Similar to the XM Series, the unit is portable and shop-floor ready, so measurements can be taken in any location including in the machine tool. The unit also automatically records measurement data and creates detailed inspection rep...
Read more

EV Charging station Market Analysis

 EV Charging station Market Analysis In the first phase of Electric Vehicles (EV) rollout plan, the power ministry is targetting 4 billion-plus population cities under the EV policy initiative. It plans to cover all the state capitals, union territories, major highways and key cities under the second phase. The electric vehicle charging infrastructure market in India is anticipated to grow at a CAGR of over 40% during the forecast period 2019-2025. Increasing government support is one of the major factors driving the electric vehicle charging infrastructure market in India. Based on component, the electric vehicle charging infrastructure marketing India is segmented into hardware and software & services. Hardware comprises sockets, cables, and charging units. Software & services include installation and maintenance of charging units, platform as a service, and other services. Other services include battery delivery service and towing service, which are in a very nascent sta...
Read more

Cochran Boiler

Image
  Cochran Boiler:  Definition, Parts or Construction, Working Principle, Advantages, Disadvantages, Application Cochran Boiler is a simple  fire tube boiler  with multiple fire tubes. It is a modification of a simple vertical boiler. In the Cochran boiler, the heating surface is replaced with multiple fire tubes that’s why it is the modification of Simple Vertical Boiler. Cochran boiler has greater efficiency comparatively Simple vertical boiler. Here in this article, we are going to study  Definition, Parts or Construction, Working Principle, Advantages, Disadvantages, and Application in very detail. Cochran Boiler Definition: Cochran boiler is a fire tube boiler (Fire inside the boiler and water surrounding them) in which coal or gases as a working fluid is used, for generating the steam,   and that steam is   further used for several purposes. Now comes to the construction, Cochran Boiler Parts or Construction: Cochran Boiler consists of the followi...
Read more