What is the Principle of Gears?
It works on the fundamental principle of thermodynamics, the law of conservation, or the first law of thermodynamics. which states that energy can neither be created nor destroyed, we can say it is conservative. It can be transformed from one form to another. We know that power is the function of torque (force in rotary motion) and speed (P = TV) of the shaft. Therefore, when we connect a small gear on the driving shaft and a larger gear on the driven shaft, the driven shaft speed decreases per unit rotation of the driving shaft.
As we know, power is conservative, so according to this, the torque of the driven shaft increases according to the ratio of driving gear to driven gear, or we can say, according to the ratio of driving shaft velocity to driven shaft velocity. Therefore, by using various sizes of gears, we can obtain various combinations of torque and speed of the driven member.
What are the Types of Gears?
There are plenty of ways in which we can classify the gears, such as according to the construction of teeth, use, the direction of motion transfer, etc. However, primary gears are classified according to the design of teeth. The most common types of gears along with their applications are enlisted in the below table.
Type of Gear
Power Plant Machinery
Railway Track Inspection Machines
Rack and Pinion
Lifting Mechanism (Vertical Movement)
Worm Drive Speed Reducers
These gears are used to transfer power in the same plane as when the driving and driven shafts are parallel to each other. In this type of gear, the teeth are parallel to the axis of the shafts, so when it meshes with another spur gear, it transmits the power in a parallel shaft, and when it connects with the helical gear, it will transmit power at an angle from the driving axis.
Teeth on helical gears are cut at a 45-degree angle to the axis. It has helicoid teeth on a cylindrical roller. Helical gears have the advantage of producing less noise and vibration than spur gears since the load is dispersed across the entire helix. They are also commonly used in industries since they are less prone to wear and tear. It's also used to transmit power in parallel shafts, but it's also used in non-parallel shafts on occasion. In helical gears, if the pinion (driving gear) is cut with right-handed teeth, the gear (driven gear) is cut in the opposite direction with left-handed teeth.
Double Helical or Herringbone Gear
This gear has both right and left-handed teeth on one gear. Power is transmitted between parallel shafts using the double-helical gear, often known as the herringbone gear. It was created to offset the drawback of single-helical gears' high-end thrust.
A bevel gear is a toothed rotating mechanical device that transfers mechanical energy or shaft power between shafts that cross at an angle or perpendicularly. As a result, the shaft power's axis of rotation changes. Apart from this, bevel gears can also increase or decrease torque while causing the angular speed to change in the opposite direction.
Rack and Pinion Gear
In automotive steering systems, this gear is used. In this sort of gear, teeth are cut on a rack with a straight rectilinear shape, and a pinion is one spur gear. This is the process of converting rotary motion into linear motion. It is referred to as the infinite radius driven gear.
This gear transmits power to a shaft that does not intersect and is at an angle. In this design, the driving gear is a screw gear, while the driven gear is a spiral-toothed helical gear.
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