What are the advantages of the constant chord method?
The advantage of the constant chord method is that for all number of teeth (of same module) value of constant chord is same. In other words, the value of constant chord is constant for all gears of a meshing system.
What is PCD in a gear?
Pitch Circle Diameter (PCD) – Gear Terminology Standard pitch circle is called standard circle or pitch circle and its diameter is obtained as the product of the number of teeth and the module. The center distance of two meshing gears is expressed as the sum of the pitch circle radii of the two gears.
What are the different method used for gear measurement?
There are three methods for determining this value: chordal tooth thickness measurement, span measurement, and over pin or ball measurement. For this article, we will discuss chordal tooth thickness measurements.
How accurate is a Vernier micrometer?
The expected accuracy of a micrometer as established using the Vernier scale is 0.01mm.
What is the main disadvantage of gear tooth Vernier?
Possibility of Errors Taking a series of measurements one after the other can lead to reading errors, because concentration is required.
What is JJ in rims?
JJ refers to the contour of the bead seat on the wheel, essentially its shape ( “J” indicates the shape of the letter J).
What is pressure angle on a gear?
The pressure angle of a gear is also the angle between the line of action and the line tangent to the pitch circles of mating gears. Figure 57.26 illustrates the relationship of the pressure angle to the line of action and the line tangent to the pitch circles.
Why are micrometers so accurate?
Micrometers use the screw to transform small distances (that are too small to measure directly) into large rotations of the screw that are big enough to read from a scale. The accuracy of a micrometer derives from the accuracy of the thread-forms that are central to the core of its design.
Are micrometers more accurate than calipers?
Micrometers are more accurate. A typical micrometer is accurate to 0.0001″ and a caliper is only accurate to 0.001″. This makes a micrometer 10x more accurate than a caliper. Also, if you were to buy a larger versions of these tools they will often have lower accuracy.
How to measure the thickness of a gear tooth?
In gear tooth vernier method the thickness is measured at the pitch line. Gear tooth thickness varies from the tip of the base circle of the tooth, and the instrument is capable of measuring the thickness at a specified position on the tooth. The tooth vernier caliper consists of vernier scale and two perpendicular arms.
What are the methods of measuring gear error?
2. Direct Angular Measurement It is the simplest method for measuring the error by using set dial gauge against a tooth. in this method the position of a suitable point on a tooth is measured after the gear has been indexed by a suitable angle. If the gear is not indexed through the angular pitch the reading differs from the original reading.
How to check the quality of gears?
For proper inspection of gear, it is very important to concentrate on the raw materials, which are used to manufacture the gears, also very important to check the machining the blanks, heat treatment and the finishing of teeth. The gear blanks should be tested for dimensional accuracy and tooth thickness for the forms of gears.
What are the steps involved in measuring gears?
GEAR MEASUREMENT Gears are the devices meant for power transmission. For proper working the gears should be measured and inspected in each steps as: Raw materials. Machining the blanks. Heat treatment. The cutting and finishing operations. The accuracy depends on: The measuring equipment available. Errors in the tooth surface finish