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.
How many gear ratios are in a planetary gear set?
Single-stage planetary gearhead ratios range from
3:1 to 10:1
. Gear ratios cannot exceed 10:1 because pinion gears can be made only so small. Gear ratios greater than 10:1 are possible with an additional planetary stage, although this normally increases length and cost.
How is direct drive achieved in a planetary gear set?
With a planetary gear a so-called direct drive is also possible. All components of the planetary gear are then firmly connected to each other. The transmission ratio in this case is
i=1
. Such a direct drive is used, for example, in three-speed gear hubs as the “2nd gear”.
How does a planetary gear set 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 planetary ratio?
The planet gears (blue) turn in a ratio
determined by the number of teeth in each gear
. Here, the ratio is −24/16, or −3/2; each planet gear turns at 3/2 the rate of the sun gear, in the opposite direction.
What is the purpose of a planetary gear?
Generally, planetary gears are used as
speed reducers
. They are used to slow down motors and increase the torque. Torque is the working power of the machine.
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.
Why are planetary gears used in automatic transmissions?
The planetary gear train is a
mechanical system in which the gears are connected with a set of bands and clutches
. When the driver changes gears, the bands hold one gear still while rotating another to transmit torque from the engine and increase or decrease gears.
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.
Which of the following is a component of a planetary gear set?
A planetary gear set is made up of three types of gears;
a sun gear, planet gears, and a ring gear
. The sun gear is located at the center (yellow), and transmits torque to the planet gears (blue) which are typically mounted on a moveable carrier (green).
How many forward ratios can a simple planetary gear set create?
Technician A says a simple planetary gearset can provide two reverse gear ratios. Technician B says a simple planetary gearset can provide
two forward reduction ratios
. Who is correct? Technician A says if the sun and the ring gear are both driven [locked] and the carrier is the output, the condition is direct drive.
What is planetary gear reducer?
A planetary gear reducer is
a type of gearbox that aims to transmit a maximum torque in the most compact form
. It decreases the number of motor revolutions and ensures high torque through the speed sensor.
What holds planetary gear components?
Planet Gears and Planet Carrier
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.
How are planetary ratios calculated?
To make calculating planetary gear ratios as simple as possible,
note the number of teeth on the sun and ring gears
. Next, add the two numbers together: The sum of the two gears’ teeth equals the number of teeth on the planetary gears connected to the carrier.
Are planetary gears more efficient?
Because planetary gearboxes do all these things with higher stiffness, less backlash,
better efficiency
, and lower noise than other gear types. … As the sun gear rotates, it drives the planetary gears to spin on their own axes and revolve around the sun gear.
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.
What machines use planetary gears?
Automated guided vehicles (AGV)
Customer-specific planetary gears are frequently used in automated guided vehicles (AGV) – whether in intra-logistics, medical device technology or agricultural technology. The gearboxes are used in wheel hub drives, as they enable a compact design in narrow spaces.
What is a planetary carrier?
[′plan·ət ¦kar·ē·ər] (mechanical engineering)
A fixed member in a planetary gear train that contains the shaft upon which the planet pinion rotates
.
What is Gearbox ratio?
The gear ratio in a transmission is
the ratio between the rotational speeds of two meshing gears
. … The gear ratio is calculated by dividing the output speed by the input speed (i= Ws/ We) or by dividing the number of teeth of the driving gear by the number of teeth of the driven gear (i= Ze/ Zs).
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.
What is the difference between Simpson and ravigneaux planetary gear set?
Use of a common sun gear
immediately distinguishes a Simpson gearset from the rival Ravigneaux gearset, which has two sun gears of different sizes, using short and long planet gears on a common planet carrier to mesh with a single ring gear.
How does a gear reducer work?
The output gear of a speed reducer has
more teeth than the input gear
. So, while the output gear might rotate more slowly, reducing the speed of the input, the torque is increased. So, to sum up, they take an input power source and increase the torque while decreasing the speed.
How does a planetary motor work?
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. … Torque is limited in spur motor gears since each gear bears the whole load.
How do I choose a reducer?
The first step in selecting a gear reducer is to know the
required torque and speed
as well as the most suitable type of motor to use. Then, it can be determined if a gear reducer is needed in the particular case. If so, then the next step is to select the proper type and ratio.
