Gears are mechanisms used to transfer motion from one shaft to another. From automobiles to machinery. Gears are used to transfer motion from one shaft to another. Different types of gears have different applications. For Example, spur gears are used to transfer motion between parallel shafts. Whereas Rack and Pinion gears are used to convert rotational motion into linear motion. In this article we will discuss various types of gears and their applications.
Types of Gears
According to type of motion, a gear transfer from one shaft to another. Gears are classified in the following types. Each gear type has different applications.
Spur gears are a type of simple gear. They have teeth parallel to the gear axis. Spur gears are used to transmit power between parallel shafts. They have applications in:
- Mechanical Clocks etc.
- Simple in construction and easy to manufacture.
- Low Cost and high efficiency.
- Various gear ratios can be achieved.
Helical gears have teeth inclined to the gear axis. For the same width, helical gears have longer teeth compared to spur gears. Therefore they can transfer more power between parallel shafts compared to spur gears.
Helical gear are used to transfer heavy loads at very high speed between parallel shafts. Applications of helical gear includes:
- Automotive gearboxes.
- Printing and other machinery
- Conveyors and elevators
- Factory Automation etc.
- Higher load carrying capacity and contact ratio compared to spur gears.
- Smoother and quieter than spur gears.
- Good precision rating.
- Lower efficiency compared to spur gears.
- Helix angle also increases axial thrust on the shaft.
Herringbone and Double Helical Gear
They are double helical gears with opposite helical teeth. Double Helical gear has a groove in the middle between the teeth. Whereas Herringbone gear does not have groove.
Both gear types are used to transfer power between parallel shafts. Compared to helical gear they offer the advantage of balancing axial thrust in both directions.
Herringbone gears are used for high load carrying capacity requirements. Therefore they are used in Differentials and heavy machinery.
- Reduced axial force
- Smoother transmission and engagement
- Reduced noise
- Self centering capability
- High load capacity
- Difficult to manufacture
- High Cost.
Rack and Pinion
A rack is a cylindrical gear with infinite radius. Whereas pinion is a spur gear. They are used to convert rotational motion into linear motion.
Since rack is a gear with infinite length. Which is not possible in the real world. Therefore rack and pinion gears can not transfer continuous motion. Therefore they are used to transfer transnational motion.
Rack and Pinion Gear application includes:
- Convert car steering wheel rotation into side motion of wheels.
- Lifting Mechanisms
- Shaper machine.
Bevel gears have a cone surface and its teeth are cut along that cone surface. These types of gears are used to transfer motion in perpendicular direction at higher velocity ratios. Bevel gears have applications in:
- Machine Tools : Lathe and milling Machine.
- Garden Equipment.
- Positioning Equipment
- Automotive differentials and right angle drives etc.
1) Straight Bevel Gear
Straight bevel gears transfer power between perpendicular shafts.
- Operate under high speeds and high loads.
- Good precision rating.
- Difficult to manufacture
2) Spiral Bevel Gear
Spiral bevel gears transfer power between perpendicular shafts. They have applications similar to straight bevel gears.
- Higher load carrying capacity compared to straight bevel gear
- Smooth Operation
- Lower efficiency compared to straight bevel gear.
Worm and Worm Wheel
Worm and worm wheel consists of a worm (similar to a screw) and a worm gear (Helical gear). They are used in right-angle skew shafts. These gears have a sliding contact. To reduce friction worm is manufactured in hard material whereas worm wheel is manufactured in soft material.
Worm and Worm wheel gear has application in devices both at home and in heavy machinery. Some of its applications include:
- Elevators and Lifts
- Tuning Instruments : Guitar
- Of Road Vehicles
- Gear engagement occurs without any shock.
- Compact Drives
- Quieter operation
- High reduction ratios (8 to 400)
- Considerable amount of heat is produced due to Friction.
- Low Efficiency (from 90% to 40 %)
- Higher speed ratio gears are non-reversible.
- Lubrication is required for heat dissipation and for improving efficiency.
Spiral Gears are also known as crossed helical gears with high helix angle. They are used to transmit power between two non-intersecting non-parallel shafts.
They are used for low load and low speed applications such as instruments, sewing machines etc.
- Poor precision rating
A Hypoid Gear is a type of spiral bevel gear whose axis does not intersect with the axis of the meshing gear. The shape of a hypoid gear is a revolved hyperboloid. In other words pitch surface of the hypoid gear is a hyperbolic surface.
Hypoid gears are typically used in rear-drive automobile drive trains. Buy now these gears are replaced by spiral gears. But these gears are still common in large vehicles because they can transfer large torque.
Internal Gears transmits power between parallel shafts. In this bigger gears have teeth on the inner periphery and both driver and driven gear runs in the same direction.
Internal gears has applications involving planetary gear drives (Planetary, solar and star) and gear couplings.
- Very Compact in size
- Not recommended for precision meshes because of design, fabrication, and
To sum up, various types of gears are used to transfer motion from one shaft to another. For Example, spur gears are used to transfer motion between parallel shafts. Whereas Rack and Pinion gears are used to convert rotational motion into linear motion.
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