Aeronautics, mining, manufacturing chains in the automotive sector, pharmaceutical industry, textiles… the sectors and fields in which you can find machines that use different types of gears are abundant.
The progressive replacement of old belts and pulleys by gears is due to the higher performance they provide.
Gears, whose basic operation is based on the coupling between a crown and a pinion as sprockets, are manufactured in various materials and with various tooth widths, face width, head circumference and circular pitch.
In this article we are going to explain the most important modalities of the different types of gears
Gear types on the market
Next, we will look at several subtypes that can be made of the different types of gears that are most commonly used today.
According to their teeth: parallel axis and perpendicular axis
The main distinction of the types of gears available on the market is made according to the position and shape of their teeth. In this sense, they are classified into parallel axis and nonparallel axis gears.
Parallel Axis Gears
- Spur Cylindrical Gears. They generate radial reaction loads on the axis and transmit power through parallel shafts. This type of gear is the simplest and is usually used for small and medium speeds, as it generates noise when if the speed increases.
- Helical Cylindrical Gears. The power transfer occurs in the same way as in the previous gear type, but now the axis can be nonparallel (auger-crown) or parallel. Their teeth are oblique in relation to the rotation axis and they transmit more movement and at a higher speed than spur cylindrical gears. They are more fluid and silent, but instead require more lubrication and wear more quickly.
- Double Helical Gears or Herringbone Gears. They combine the right and left helix. A symmetrical branch generates an opposite and equal thrust. They eliminate the axial thrust, which means that bearings and supports no longer have to absorb it.
Parallel axis gears include spur, helical and double helical cylindrical gears.
Nonparallel Axis Gears
- Screw Gears (Crossed Helical Gears). They perform a wedge or screw movement, which results in a high degree of slip on the tooth flanks. Easy to assemble, they must have the same normal diametrical steps for the gear to be adequate. They can go in the same direction or in the opposite direction.
- Spur or Straight Bevel Gears. Little used nowadays, they transmit the movement of axis that are cut in the same plane, usually in right angle, by means of conical toothed surfaces. The teeth converge at the intersection of the axes. They are often used to slow down with axes positioned at 90 degrees and are noisy.
- Spiral Bevel Gears. Their contact surface is larger compared to straight bevel gears. They can transmit the motion of axis that are cut and used to lower the speed on shafts of 90 degrees.
- Hypoid Gears. Their attack pinion is off-center in relation to the axis of the crown. They stand out for their long service life and the low noise they generate, although they require extreme pressure oils. They are used in boats and industrial machines.
- Worm Wheels and Worm Screws They have a worm screw, which functions as a conductor, and a crown, driven by it. The screw moves the crown with its turn. Although its most common angle between axes is 90 degrees, it can be different.
For more information: Helical gears or spur gears?
Gear types for special applications
- Internal or Ring Gears. They are similar to spur gears, although their teeth are not ground on the outside, but on the inside of a wheel or rimmed ring. A pinion drives the inner gears and maintains the direction of angular velocity.
- Planetary Gears. Also called epicyclic gears, it is a gear train in which a central gear has one or several external gears around it. They are commonly used for automobile transmissions.
- Rack and Pinion. Used in lathes to move the longitudinal carriage, they do not have a transmission ratio, but a length ratio. In this case, it is referred to as the distance between axis, since the rack falls within the category of gears of infinite diameter.
Materials used to manufacture gears
Tempered steel is one of the most common materials for different types of gears, and aluminum is also common. Other materials used are:
- High strength steels
- Forged stainless steels
- Copper-based alloys
- Cast or forged aluminum alloys
- Cast iron or grey cast iron
- Magnesium alloys
As for plastic materials, which have self-extinguishing properties, polycarbonate (PC), polyamide or PVC stand out, as well as acetal resins. Moreover, among non-fuel materials, the most commonly used are polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE) and liquid crystal polymers (LCP).
This might interest you: Why improve your safety mechanisms with flame retardant plastics
Applications & Utilities of Gears
The different types of gears are present in many sectors, such as:
- The agricultural sector, in which they play a key role in carrying out mechanized tasks, such as sowing, ploughing or irrigation, as well as in the tractors themselves.
- In the automotive field, their function is usually to act as transmitters of forces and to regulate speed.
- As for naval vehicles, gears operate on fishing boats, submarines, workboats or yachts.
- In the generation of wind power, gears increase the speed of generators, a function that is also used by cement manufacturing industries. Roller mills are used for the transport of slabs and for wire rolling mills.
In addition, there are four applications of gears that are particularly emblematic, and which are implemented in countless sectors and fields:
1. Hydraulic Pump
It converts rotary mechanical energy into hydraulic energy. It consists of a pair of coupled gears and has the driven shaft and the driver, which is driven by the motor shaft.
This one, due to the displacement caused by the contact between the teeth of the gears, rotates the driven shaft.
2. Speed Reducer
They use circular and toothed gear pairs to lower the motor speed efficiently and safely. In addition, they use gears with very different diameters to reduce the speed of rotation.
3. Differential
Widely used in the automotive sector, it makes it easier for the two driving wheels of a vehicle to turn at different speeds than the others.
A differential is made up of two planetary gears attached to the ends of the semi-axles of the wheels, and two other satellites or conical pinions located at the ends of their satellite-carrying axle.
4. Gearbox
It couples the motor with the transmission system through different gear ratios. It also reduces the engine speed.
Some ball bearings support the gear shafts. It is coupled to the motor flywheel via the clutch or torque converter.
How and where to find the right gear types
Choosing the right type of gear is essential to avoid downtime and costly repairs in any industrial environment.
The efficiency of these mechanisms is determined by several factors, such as design, contact force, bending strength or vibration generated by the various couplings between the gears..
Related reading: Tips to Consider When Buying Gears
CLR (Levantine Gear Company) offers a consultancy service in engineering and integral prototypes design, as well as a wide catalogue of mechanical components and an established experience in the sector, with more than 25 years of specialization.
All this has led CLR to position itself as a benchmark in the manufacture of gearmotors and gearboxes, allowing it to guarantee total satisfaction with the performance of its products.
Leading a team of engineers using the latest technology, CLR is a full partner in logistics, manufacturing and customer service, enabling it to meet the highest demands and provide a full advisory service.
Need to find the right component for your drive projects? Get in contact with us and we’ll assist you.