Category: Power Transmission Devices

When an annular gear A is used in epicyclic gear train, it is known as sun and planet gear train. The annular wheel meshes with wheel P and rotates as sun and planet gear as shown in Figure 15.28. The wheel S and P are, generally called the sun and the planet wheels, respectively due to analogy…

If the axis of at least one gear in gear train moves relative to fixed axis or frame, such type of gear train is known as epicyclic gear train. In this gear train, one gear rotates over pitch circle of other gear as shown in Figure 15.27. Consider two gear wheels P and Q, the axes of…

If axes of the first and the last wheels of a compound gear coincide, it is called reverted gear train. Example 15.9: In a reverted gear train, speed ratio is 10 as shown in Figure 15.26. The module of gear 1 and 4 is 3 mm and module of gear 2 and 3 is 2 mm. Calculate the…

When two or more gears rotate about same axis and have same angular velocity, it is known as compound gear train. Figure 15.25 shows the example of compound gear train. Figure 15.25 Compound Gear Train Example 15.8: A motor shaft is connected to gear 1 which rotates at 50 rpm. Find the speed of output shaft gear 6 (Figure…

In this gear train, all the gears are mounted on their separate shafts and the gear axes remain fixed in a frame. All the paired gears are moved in opposite directions. All the gears can be in straight line or in zig-zag manner. Figure 15.24 shows the example of simple gear train. Example 15.7: There are four gears…

Gear trains are various types of combination of gears to transfer power from one shaft to another. Gear trains can be classified as follows: Figure 15.24 Simple Gear Train

Bevel Gears Bevel gears are primarily used to transfer power between intersecting shafts. The teeth of these gears are formed on a conical surface. Standard bevel gears have teeth which are cut straight and are all parallel to the line pointing the apex of the cone on which the teeth are based as shown in Figure…

Double helical gears have one a right-hand helix and the other a left-hand helix. The teeth of two rows are separated by a groove used for tool run out. Axial thrust which occurs in case of single helical gears, two rows of teeth cancel each other. This can be run at high speeds with less…

Helical gear is similar to the spur gear except that the teeth are at an angle to the shaft, rather than parallel to its axis as in a spur gear. The resulting teeth are longer than the teeth on a spur gear of equivalent pitch diameter. The longer teeth cause helical gears to have the…

General: Spur gears are the most commonly used gear. They are characterized by teeth which are parallel to the axis. The basic descriptive geometry for a spur gear is shown in Figure 15.18. Advantages: Spur gears are easy to find, inexpensive, and efficient. Limitations: Spur gears generally cannot be used when a direction change between the two shafts is…