Table of Contents
How do planetary gears work?
A planetary gear set is comprised of an outer gear ring that’s called the ring gear. As they rotate inside of the ring gear, the planetary gears create pitch circles that can be formed into a gear train that, in turn, is hooked up to input and output shafts.
What is the purpose of planetary gear sets?
Planetary gears are often used when space and weight are an issue, but a large amount of speed reduction and torque are needed. This requirement applies to a variety of industries, including tractors and construction equipment where a large amount of torque is needed to drive the wheels.
How do planetary gears increase speed?
The output of the second stage planetary gear mechanism uses a large diameter gear to drive the pinion to continue to increase speed. All gears use helical gears to make the transmission smoother.
How does a planetary final drive work?
The planetary gears mesh with the sun gear and turn while rolling around the ring gear. They spin at a slower rate than the sun gear, and that speed reduction increases torque. These gearing relationships and the power they provide is known as your final drive ratio.
How do planetary gears differ from other gears?
In a planetary gearbox, many teeth are engaged at once, which allows high speed reduction to be achieved with relatively small gears and lower inertia reflected back to the motor. Having multiple teeth share the load also allows planetary gears to transmit high levels of torque.
What is a planetary carrier?
The planetary carrier is a functional component that is crucial for planetary transmissions in conventional powertrains and electric powertrains. It can be described as a cage into which the planetary gears are integrated.
Why do automatic transmissions have planetary gear sets?
The torque converter clarifies how the engines send power to the transmission, but the planetary gear sets explain how an automatic transmission changes gear. The planetary gear set is really the heart of an automatic transmission. This one part creates all the possible gear ratios that the transmission can produce.
Can planetary gears be back driven?
A 10:1 is very easy to back drive. The largest ratio planetary gearbox I have back driven was a two stage 100:1. On a side note, if you are driving the gearbox with a DC or servo motor you will probably have to disable the dynamic braking to back drive it.
How many gears does a planetary gear set have?
An epicyclic gear train (also known as a planetary gearset) consists of two gears mounted so that the center of one gear revolves around the center of the other.
How do planetary gears increase torque?
The planet gears are mounted on a joint carrier that is connected to the output shaft. The rotational speed of the output is lower than that of the drive, and the torque of the output is higher in reverse proportion. The more gear wheels mesh with each other, the higher the torque.
Who invented the planetary gear set?
The Ravigneaux gearset is a double planetary gear set, invented by Pol Ravigneaux, who filed a patent application on July 28, 1949, in Neuilly-sur-Seine France. This planetary gear set, commonly used in automatic transmissions, is constructed from two gear pairs, ring–planet and planet–planet.
What is planetary gear motor?
A planetary gear motor mimics a planetary rotation system, the input shaft drives the central gear, also known as the sun gear, which then turns the surrounding gears, also known as planet gears. As these Epicyclic Gear Train motors are very popular amongst Robotics designer.
How do you calculate torque of a planetary gearbox?
ANALYTICAL CALCULATIONS Input torque = (60*voltage*current)/ (2*22/7*input speed) 2. Output torque = (60*voltage*current)/ (2*22/7*output speed) 3. Holding torque = Output torque – Input torque.
How is a 1 1 ratio achieved using a planetary gear set?
If both sun gears turn in the same direction, the planet gears lockup because they can only spin in opposite directions. This locks the ring gear to the planets and causes everything to spin as a unit, producing a 1:1 ratio.
What causes planetary gears to fail?
Planetary gearbox are exposed to high speed reduction mostly because of their capability and compact size. Faulty design is not only the reason for gearbox failure, manufacturing and material handling can be one. In planetary gearbox, noise is usually no worse, and often better than standard gear-and-pinion reducers.
Are planetary gears more efficient?
In addition to their durability, planetary gear motors also provide a higher efficiency over spur gear motors. Due to the construction of a planetary gear head, the length of a planetary gear motor is usually longer and narrower than spur gear motors.
What machines use planetary gears?
Planetary gear train (PGT) has been widely used in the transmissions of helicopters, automobiles, wind turbine, aircraft engines, etc. The main advantages of this transmission are its high efficiency, its compactness, its large transmission ratio and its large power-to-weight ratio, etc.
At what RPM should you shift gears?
Generally, you want to shift gears when your car reaches 2,500-3,000 RPM. Eventually, you will know when to shift by sound and feel.
Do manual transmissions use planetary gears?
The main difference between manual and automatic transmissions is that the manual transmission uses multiple sets of gears to the drive shaft while an automatic transmission uses a planetary gear set to produce different gear ratios.
Do automatic transmissions use planetary gears?
They also form the basis of the most common type of automatic transmission, known as the hydraulic planetary automatic transmission. Most modern automatic transmissions in the automotive industry use planetary gears. Automatic transmissions of all types carry planetary gears, such as this 10-speed from Ford.
What are planetary axles?
Planetary Axles. These planetary axles are engineered and manufactured to offer maximum gross axle weight rating (GAWR) at 126,000 pounds for tridem axles to carry higher-capacity loads.
How many planet pinions are used in a planetary gear set?
Planet (pinion) gears revolve around the sun gear. They are held together by a carrier assembly. There can be either three (3) or four (4) planet gears in the planet carrier. The planet carrier keeps the gears equally spaced apart allowing them to evenly support the ring gear from the sun gear.
