Stepped planetary gear ratio. The second gear step engages with sun gear #2.

Stepped planetary gear ratio. The second gear step engages with sun gear #2.

Stepped planetary gear ratio. The planet gears are mounted on a carrier, which rotates around the sun gear. The gearbox output torque is up to 143 oz-in (1 Nm) "Compound planetary gear" is a general concept and it refers to any planetary gears involving one or more of the following three types of structures: meshed-planet (there are at least two more planets in mesh with each other in each planet train), stepped-planet (there exists a shaft connection between two planets in each planet train), and A continuously variable transmission (CVT) is an automated transmission that can change through a continuous range of gear ratios, typically resulting in better fuel economy in gasoline applications. In stepped-planet gears, there’s a shaft connected between two planet gears. In this article, we will discuss how to calculate the gear ratio and explore the wide array of planetary gears we offer. INTRODUCTION Planetary gear systems normally consist of a centrally pivoted sun gear, a ring gear, and several planet gears found between the sun gear and ring gear. Gear Assy 2 (not featured to provide a better Gear Generator is a tool for creating involute spur gears and download them in DXF or SVG format. In contrast, there are only a few investigations regarding stepped planetary gear systems. In planetary gears, torque density can be increased by adding more planets through multiple gear Aug 30, 2018 · Planetary gear sets contain a central sun gear, surrounded by several planet gears, held by a planet carrier, and enclosed within a ring gear The sun gear, ring gear, and planetary carrier form three possible input/outputs from a planetary gear set Typically, one portion of a planetary set is held stationary, yielding a single input and a single output, with the overall gear ratio depending on Epicyclic Gearboxes (Planetary gearboxes)have the following features Typical Epicyclic Gear Arrangement There are three configurations possible with this epicylic gear Star where the planet carrier arm is fixed and the sun and annulus ring gear rotate. These systems work with a central "sun" gear that connects with several "planet" gears. You'll learn the key formulas, examples, and important 3 days ago · Here's some info: The early TH 400 had I think sun gear with 39 teeth planet pinions with 21 teeth ring gears with 81 teeth each. Nov 5, 2023 · The compound stepped planetary gear (CSPG) drive has a higher speed ratio than simple planetary gear drives, but the selection of gear teeth for CSPG drives is more stringent due to their complex structure. The kinematics of a planetary gear set can be analyzed using the lever analogy. 17. A carrier connects the centers of the two gears and Planetary or Epicyclic Gear gear ratios are the rates at which the selected gears rotate relative the mechanical advantage. I'm using Fusion360, t Epicyclic Gears - Ratio Calculation. Keywords: planetary system, all-purpose all-round differential mechanical diagram, friction lock-up clutch, friction brake gear train, Understanding and Calculating Planetary Gear Ratio Planetary gear systems are fundamental in numerous applications due to their high power density, smooth operation, and versatility in configuration. Technical explanations and interactive examples are provided for the kinematics of different gear system architectures. Reference: Roymech. Try it now! 1. Later Turbo 400 Ratios: Sun Gear = 26 Tooth Ring Gears = 54 Tooth Planet Pinions = 14 Tooth This is what some aftermarket gear set is (was?) the sun gear has 36 teeth annulus A has 90 teeth annulus B has 66 teeth This comes out to 2. The design of a new eight-diameter stepped planetary gear box was produced. This opens up our gearing ratio options a little bit. In addition it let you compose full gear layouts with connetcted gears to design multiple gears system with control of the input/output ratio and rotation speed. What are the advantages of multi-stage planetary gearboxes? A key purpose of drivetrain systems is to modify the magnitude and direction of angular velocity between two points in the system. Because of these three key features, planetary gearboxes are used in countless applications, such as in industrial machines, agricultural, medical, wind turbines, robots, automatic transmission and so on. Therefore, they are very suitable for applications where the size of gearboxes is limited, e. Sep 1, 2008 · The force at the second ring gear mesh results from the output torque on the ring gear. Planetary Gear Calculator Design your planetary gear speed reducer with this tool. Due to the possibility of high speed-ratios, compound stepped planetary gear drives (CSPG) are very suitable for applications with size restrictions, e. com Oct 2, 2025 · Understanding Planetary Gearbox Ratios and Calculations The kinematics of a planetary gear set are more complex than a simple gear train due to its multiple moving elements. The gear ratio formula for two meshing gears is simple and intuitive, while the gear ratio formula for the planetary mechanism is not. 8° NEMA 8 Geared Stepper Motor with Planetary Gearbox NEMA8 is our smallest size of geared stepper motor. The Willis equation is often used to relate the speeds of different components. Explore planetary gears, cycloidal drives, and gear simulators. Which transmission ratios result in each case, is shown in the next section. High-ratio designs often correlate with low mechanical efficiency or large volume in most parametric spaces. It is given by the formula GR = (N2 - N1) / (N3 - N2), where N1 is the number of teeth on Sep 21, 2018 · In manual transmissions, the shifting of various transmission ratios is performed by clutches that allow certain components (sun gear, carrier or ring gear) to be fixed depending on the desired gear. Explanation Calculation Example: A 2-stage planetary gearbox is a type of gearbox that uses two sets of planetary gears to achieve a high gear ratio. Learn how gear ratios work with expert guides and step-by-step calculations. This ratio is calculated by dividing the number of teeth on the sun gear by the number of teeth on the ring gear. Input and output are then carried out by the other two components. The ratio being 41. Thus the diameter ratio between the sun gear and the planet gear determines how often the planet gear rotates around its own axis while it moves once around the sun gear. The stepped planet gears (1) are driven by the ring gear (1). However, the transmission ratios can Calculate Ratios for Simple and Compound Planetary Gear Trains; Epicyclic Gear Train Configurations. We’ve provided complete instructions below the calculator to help you use the calculator. Ideal for engineers and designers. The large step wheels (4) of the second stepped planetary gears engage the sun gear (2), the small step wheels (6) of the second stepped planetary gears Compared to simple planetary gears, compound planetary gears have the advantages of larger reduction ratio, higher torque-to-weight ratio, and more flexible configurations [3]. This notebook reviews the unique geometric attributes of planetary gears and their significance to planetary gear mesh operation. How Planetary Gears Work A planetary gear set is composed of four Jun 16, 2025 · A planetary gearbox, also known as a epicyclic gearbox, is a type of gear system that consists of one or more outer gears, or planet gears, rotating around a central gear, or sun gear. Aug 8, 2023 · Master the art of calculating gear ratios for planetary gears with Me Virtuoso. In the image shown above, if my input was the blue sun gear, the output was the planet gear, and the ring is assumed to be fixed, how can I go about deriving what the gear ratio would be? Mar 10, 2021 · With a single planetary gear set one will obtain three different modes of operation, depending on which component (sun gear, carrier or ring gear) is fixed. For the sun gear, the speed of eight-diameter stepped planetary gear box is presented and calculation of gear transmission ratio with the operation concept is stated. Use cases are given to formulate and solve angular velocities in parallel and planetary gear Nov 5, 2023 · The compound stepped planetary gear (CSPG) drive has a higher speed ratio than simple planetary gear drives, but the selection of gear teeth for CSPG drives is more stringent due to their complex (3) where denotes the input torque (from a motor for example), denotes the number of planet gears denotes the tangential force at the interface between the sun gear and each planet gear (we assume here that all planet gears share the load evenly), and denotes the polar moment of inertia of the sun gear. Gear 1 Gear Assy 1 Ring gear (1) is driven by the sprocket. Introduction Epicyclic gear stages provide high load capacity and compactness to gear drives. 682 rotations of planet carrier (1-2) for each sprocket rotation. These planet gears then mesh with an outer "ring" gear. 17. Due to their advantages of high efficiency, compactness, and high power-to-weight ratios, they are widely used in various mechanical applications, including automotive transmissions Jan 1, 2008 · This paper presents the structured vibration mode and natural frequency properties of compound planetary gears of general description, including those with equally-spaced planets and diametrically opposed planet pairs. The satellite gears have a fixed position in relation to the outside world. Nov 21, 2024 · Within the gear carrier are three sun gears of varying size and matching stepped planetary gear sets. 1 Planetary Gear System The basic form of a planetary gear system is shown in Figure 17. g. , gear reducer for actuators in EV. Also, by changing Gear sets serve to transfer rotational motion and torque at a known ratio from one driveline axis to another. CSPG employs two compound Our planetary gear simulator for precise planetary gearbox design. Dec 8, 2022 · STEPPERONLINE Planetary Gearbox Gear Ratio 10:1 Backlash 15 arc-min for Nema 17 Stepper Motor Visit the STEPPERONLINE Store FREE Returns 1. The gear ratio of a 2-stage planetary gearbox is given by the formula R = (N1 + N2) / N3 A planetary gear set is a unique type of gearing system which provides high torque and high efficiency in a compact design. (the system contains two or more planet sets). Update: I found a paper which contained the formula for compounded gears in planetary gear train, and it matches what I see in CAD! But I am still not able to calculate the Jul 15, 2016 · 2 I need to make a planetary gear system such as the following: The sun and planet gears will be stationary (so that they can only rotate around their centers, not around the sun gear). co. planetary gear ratio calculator; Due to the possibility of high speed-ratios, compound stepped planetary gear drives (CSPG) are very suitable for applications with size restrictions, e. The second gear step engages with sun gear #2. These planetaries drive a ring gear on which is mounted a roller clutch which transmits power to the hub shell. Sun Teeth Planet Teeth Ring Teeth Sun Speed Carrier Speed Ring Speed Requires an HTML 5-compliant browser Gear image generation code from http://jsbin. If the planet gear makes 4 revolutions, the sun gear makes Aug 27, 2025 · This study explores the application of profile shift coefficients as a design strategy to eliminate the need for stepped planet gears in a specific type of planetary gear train, referred to as the AA gear train. Contact Us Now! Compound planetary gears involve one or more of the following three types of structures: meshed-planet (there are at least two more planets in mesh with each other in each planet train), stepped-planet (there exists a shaft connection between two planets in each planet train), and multi-stage structures (the system contains two or more planet sets) [6]. Compared to simple planetary gears Planetary gear ratio calculations This article also available in A question that I often get is how to work out planetary gears using the Working out the tooth counts for planetary gears is actually not that complicated, so I initially neglected to mention how to do it. Normally, the sun-gear is driven and thus move the planet gears locked in the planet carrier and form the output shaft. Mar 12, 2024 · Efficiently calculate planetary gearbox ratios, speeds, and torques with our intuitive tool, designed for engineers and hobbyists alike. Fixed frame assembly Input and output shaft rotate in opposite directions Ratios up to 10:1 (approx)-- (Reduction or increase depending on Planetary Gear:  Intro – planetary gears also refer as epicyclic gearing consisting three elements sun gear, planet gear and ring gear. Simscape™ Driveline™ contains angular gears for transferring rotational motion and torque and linear gears, for transferring translational motion and force. The gear ratio is the relationship between the number of teeth on two gears that are meshed or connected. Compared to simple planetary gears, compound planetary gears have the advantages of larger reduction ratio, higher torq Planetary gear systems are a type of gear train configuration where a central gear, called the sun, meshes with and is surrounded by planet gears, which in turn mesh with an outermost gear called the ring gear. There is a wide variety of different com-binations of planetary gear arrangements (Refs. Mar 11, 2025 · A planetary gear system consists of three main components: the sun gear, planet gears, and ring gear. This section introduces planetary gear systems, hypocycloid mechanisms, and constrained gear systems, which are special gear systems which offer features such as compact size and high reduction ratio. In all those cases, terms like "first gear", "high gear", and "reverse gear" refer to the overall torque ratios of different meshing configurations, rather than to specific physical gears. Sun gear is located at the center that transmits torque to planet gears orbiting around the sun gear. This calculation is crucial for determining the speed and torque of the gear set. Spur or helical gears each have their advantages in planetary gearing. Gears can be animated with various speed to demonstrate working mechanism Feb 4, 2013 · Compound Gears Meshed-planet gears use two or more outer gears that are meshed with each other. 1 An example of a Aug 23, 2023 · Due to the possibility of high speed-ratios, compound stepped planetary gear drives (CSPG) are very suitable for applications with size restrictions, e. Aug 20, 2024 · Thanks! I have been following the same page for my calculations but the problem is that they assume that the same planet gear meshes with the ring and sun, but in my case those two gears are different (albeit compounded). [1] This contrasts with other transmissions that provide a limited number of gear ratios in fixed steps. The pawl 1 (1) couples the sun gear 1 (1) to the axle. The result is 0. But having received the question a number of times, I'll elaborate. Add the two numbers together. The 22mm diameter planetary stepper motor gearbox has gear ratio from 1:3. Now, industrial applications demands high torque in compact (a high torque/volume) and light (a high torque/weight ratio) package. It's vital whether you're creating a new gear system or improving an old one. Introduction: An epicyclic gear is a complex planetary gear arrangement consisting of one or more planet gears (P) rotating around a central sun gear (S), with the planet gears also meshed and . , gear reducers for actuators in Download scientific diagram | Example of a stepped planet compound planetary gear from publication: Structured Vibration Modes of General Compound Planetary Gear Systems | This paper extends Oct 19, 2024 · Explanation Calculation Example: The gear ratio of a planetary gearset is given by the formula GR = (N + n) / (R - n), where N is the number of teeth on the sun gear, n is the number of teeth on each planet gear, and R is the number of teeth on the ring gear. Aug 29, 2025 · The excitation behavior of planetary gear systems has already been the subject of numerous research studies. Follow our step-by-step guide and demystify the complexities of gear mechanics. Advantages: Jan 4, 2018 · Count the number of sun gear teeth and the number of ring gear teeth if the planetary gear is set in underdrive with the carrier as the output. However, the design of the numbers of teeth of CSPG is more complicated due to the compound planets. Vector of output-to-input power ratios that describe the power flow from the sun gear to the planet gear, ηSP. Compound stepped planetary gear drives (CSPG), in par-ticular, have gained widespread use due to their superior performance under space con-straints. The vibration modes are classified into rotational, translational, and planet modes and the unique properties of each type are examined and proved for general compound planetary May 26, 2024 · Explore the mechanics and benefits of planetary gear systems, highlighting their efficiency, precision, and torque capabilities in various engineering applications. For convenience, let's denote R, S, and P as the number Abstract High-ratio compound stepped planetary transmissions are typically characterised by poor overall efficiencies, even if the individual mesh efficiencies are high, because of the very high sliding velocities imposed by the kinematics of their topologies. The block uses the values to construct a 1-D temperature-efficiency lookup table. 13 1st gear and 1. The same concepts are then extended to planetary gear trains and various methods of calculating the transmissions ratios achievable with these types of gear drives are defined. For this reason, stepped planetary gear stages are increasingly used, as they offer high power density at high gear ratios. Verification: Checked against Machinery's Handbook 27th edition, page 2115. The gear ratio is the ratio of the number of teeth on the output gear (also known as the driven gear) to the number of teeth on the input gear (also known as the driving gear). Planet gear load distribution factor, K_,, which takes into account the non-uniform load distribu-tion on the individual planets (Ky = i. They have many benefits like good gear ratio, making more torque, and being able to fit in tight spaces. How do you calculate the gear ratio in a planetary gearbox? The gear ratio is calculated based on the number of teeth on the sun and ring gears and which component is fixed. As technology continues to improve, planetary gears will likely remain at the forefront of modern mechanical engineering. The planetary gear set, also known as the epicyclic gear train, is one of the most important and interesting inventions in engineering. Jan 24, 2020 · In this chapter, the general concepts of ordinary gear trains are first described, particularly those concerning their efficiency and the obtainable transmission ratios. Input your desired target ratio, add any constraints your design needs to meet, and the algorithm will generate a range of possible combinations that meet your specifications. Jun 19, 2024 · Popularity: ⭐⭐⭐ 2-Stage Planetary Gearbox Ratio Calculation This calculator provides the calculation of gear ratio for a 2-stage planetary gearbox. How to Calculate Compound Planetary Gear Ratio and Select the Best Planetary Gears Calculating Compound Planetary Gear Ratio Calculating the gear ratio of a compound planetary gear system involves understanding the system’s configuration and the individual gear teeth count. However, it affects the torque capacity and efficiency of the gearbox. Gear Generator is a tool for creating involute spur gears and download them in SVG format. See full list on mentoredengineer. Related Questions Q: What is the advantage of using a planetary gearset? Gear Ratio Calculator This Gear Ratio Calculator is an advanced tool able to calculate up to four levels and even the ratios of planetary gear systems, using the Willis Equation. Determine how heat generation affects the efficiency and temperature of driveline components using thermal variants of gear Sun Teeth Planet Teeth Ring Teeth Sun Speed Carrier Speed Ring Speed Requires an HTML 5-compliant browser Gear image generation code from http://jsbin. Related Questions Q: What are the advantages of using planetary gearboxes? A: Planetary gearboxes offer several advantages, including a high gear ratio in a compact package, high efficiency, and smooth operation. In doing so, the stepped planet gear's first gear step rolls off the fixed sun 1 (1). 1–2). For similar epicyclic planetary stages with compound planet gears, the Dec 1, 2011 · Compound planetary gears involve one or more of the following structures: meshed-planet, stepped-planet, and multi-stage planetary gears. Based on the involute geometry, a gear mesh analysis model This planetary gear train consists of a sun gear (yellow), planet gears (blue) and carrier (green) inside a ring gear (red) An epicyclic gear train (also known as a planetary gearset) is a gear reduction assembly consisting of two gears mounted so that the center of one gear (the "planet") revolves around the center of the other (the "sun"). Compound planetary gears provide larger reduction ratios and more flexible configurations than simple planetary gears. TR = Number of teeth on the Ring Gear Step 2: Understand the Formula The gear ratio (GR) of a planetary gearbox can be calculated using the following formula based on the arrangement and type of gears involved: This formula will give you the ratio of the rotational speeds between the input and output shafts of the gearbox. For simple, epicyclic plan-etary stages when the ring gear is station-ary, the practical gear ratio range var-ies from 3:1 to 9:1. Q: How are planetary gearboxes used in practice? Apr 28, 2022 · Its design, with a sun gear, ring gear, and planet gears, allows for compactness, high transmission efficiency, and large transmission ratios. A multi-stage structure has a gear system with two or more planet sets. 1:1, output torque is 41. Aug 29, 2024 · Planetary Gear Ratio Calculator Sun Gear Teeth: Planet Gear Teeth: Ring Gear Teeth: Calculate Ratio Calculating the gear ratio of a planetary gear system might seem hard, but this guide will simplify it. uk. Both systems are locat… Oct 19, 2024 · Optimization of Planetary Gearbox Configurations via Calculator-Generated Ratios 19 Oct 2024 Tags: Mechanical Engineering Machine Design Gear Drives Planetary Gearbox Ratios Calculation Popularity: ⭐⭐⭐ Planetary Gearbox Ratios This calculator provides the gear ratio for a planetary gearbox. Jan 1, 2019 · Introducing Compound Planetary Gears (C-PGTs): A Compact Way to Achieve High Gear Ratios for Wearable Robots: Proceedings of the 4th International Symposium on Wearable Robotics, WeRob2018 In a planetary gearbox we see a sun (solar) gear, satellite (ring) gear and two or more planet gears. It consists of a sun gear A, planet gears B, internal gear C and carrier D. Explanation Calculation Example: A planetary gearbox is a type of gearbox that uses planetary Jun 22, 2024 · Planetary gear systems are a special kind of gear. A set of equations is derived for checking the assembly of gears as well as for May 10, 2024 · TECHNICAL ARTICLES | 2022-05-19 Algorithm-Based Optimization of Gear Mesh Efficiency in Stepped Planetary Gear Stages for Electric Vehicles The objective of this paper is to develop a method for the algorithm-based design and optimization of the macrogeometry of stepped planetary gear stages. My goal is to make it so that whenever the sun gear rotates $90^ {\circ}$, each planet gear will rotate $-180^ {\circ}$ and the ring gear will rotate $-90 I show how to model a ring gear, how to set up planets, carrier and sun, joints and motion links, and making helical/herringbone sets. A deep understanding of planetary gearbox ratios is crucial for designing effective Aug 23, 2023 · Compared with the simple type, the compound stepped planetary gear (CSPG) set can have a higher speed ratio under the same outer diameter of the ring gear. The fundamental formula for calculating the gear ratio depends on which component is fixed, which is the input, and which is the output. Jun 23, 2024 · Popularity: ⭐⭐⭐ Planetary Gear Ratio This calculator provides the calculation of planetary gear ratio for mechanical engineering applications. Algorithm-Based Optimization of Gear Mesh Eficiency in Stepped Planetary Gear Stages for Electric Vehicles Christian Westphal, Jens Brimmers and Christian Brecher Introduction and Motivation Increasing demands on product performance have led to high demand for optimization in component design. Optimize gearbox ratio and layout with our online planetary gear set simulator. com/oresos/latest Mar 15, 2022 · In this article, you will learn what is planetary gear? Their design, parts, functions, advantages, ratio, and uses with Pictures & PDF. Quality Planetary Gears We Produce We pride ourselves on producing high-quality planetary Sep 21, 2018 · However, the motions are not independent from each other, because the planet gear rotates on the sun gear. Understanding Planetary Gear Set Ratios Calculation Understanding the gear ratios of a planetary gear set is crucial in any mechanical or engineering application. 1 Introduction Planetary gear drives are widely used in various transmission application due to their advantageous features such as coaxial input and output shaft arrangement, high power density, and high-speed ratio. 1. Some problems related to simple planetary gear Oct 13, 2024 · A: The number of planet gears in a planetary gearbox does not directly influence the overall gear ratio. Calculating Ratios for Various Epicyclic Gear Arrangements. In this tutorial, we will show you an original and easy-to How to Calculate Gear Ratio of Planetary Gears The gear ratio of a planetary gear system is calculated using the number of teeth in the gears. The formula is (Ring Gear Teeth + Sun Gear Teeth) / Sun Gear Teeth = Gear Ratio. In a compound The design of planetary gears is reviewed for spur and helical gears. Explanation Calculation Example: The planetary gear ratio is a measure of the speed ratio between the sun gear and the ring gear in a planetary gear train. The flexibility of a CVT with suitable control may allow the engine to operate at a Mar 19, 2025 · 2. They are great speed Feb 25, 2024 · A stepped planet is where the planet gears have two different profiles: one that interfaces with the sun gear and one with the ring gear. For functional reasons, however, not all of the transmission ratios shown in the table above can be achieved with a single planetary gear (planetary gear set). 3. Previous simulation studies indicate that stepped planetary gearboxes are sensitive to axis misalignments [1]. 1 times input torque. , gear reducers for actuators in Use our Planetary Gear Calculator to determine gear ratios, speeds, and torque for planetary gear systems. Jan 12, 2021 · I was looking into planetary gearsets, and came upon the concept of a stepped planetary gearset. The first gear step of the stepped planet gears engages with sun gear #1. A simple planetary system with a stationary sun gear cannot have a step-up ratio as great as 2:1 -- the planet gears would become infinitesimally small and turn infinitely fast; a step-down ratio cannot be as low as 1:2. The sign preceding the gear ratio is positive because the ring gear is internal (the ring and planet revolve in the same direction). To increase range and energy efficiency, the gear mesh losses are of great importance and must be considered in the gear design. Adjusting for a pitch radius difference of, say, 3:1, the force on the second planet will be approximately 14 times the force on the first planet at the sun gear mesh. 7 to 1:369. 40 2nd gear Aug 8, 2023 · Understanding planetary gears and their gear ratios equips engineers with the knowledge to design efficient and compact machines. This setup can reduce speed and increase torque effectively in a small space. With sun gear 1 or 2 coupled to the axle,or the coupling of sun gear 1 with the ring gear, three ratio variations are achievable with each gear assembly. O for ideal load distribution). In order to derive the relationship of the rotational speeds between the sun gear, the planet gear and the carrier Feb 28, 2023 · Engineers can use planetary gears to increase or decrease both speed and torque, and to do so in a small, compact space. The gear ratio is a key parameter in these systems. Specific niche regions exist that combine high transmission ratio, efficiency, and small volume in the design space. Mar 10, 2021 · In the article Derivation of the Willis equation, the fundamental equation for epicyclic gears was derived in the following form: \begin {align} \label {g} &\boxed {n_p \cdot d_p = n_c \cdot \left (d_p + d_s \right) – n_s \cdot d_s} \\ [5px] \end {align} In this equation, n p denotes the rotational speed and d p the diameter (pitch circle) of the planetary gear. Fig. , gear reducers for actuators in electrical vehicles. By appropriately selecting gear tooth numbers and applying compensating profile shifts to the two central gears, it is possible to equalize their diameters, enabling the use of simple What is a Planetary Gearbox Ratio and how to calculate it? A planetary gearbox ratio refers to the relationship between the input speed (RPM) and the output speed of a gearbox. Here, a parametric exploration of the design space is presented for a stepped transmission topology, which is assessed in terms of Oct 19, 2024 · The ring gear speed is the speed of the outer gear in the planetary gear system. Compound stepped planetary transmissions can achieve transmission ratios of 100 with efficiencies exceeding 94%. com/oresos/latest The invention relates to a planetary gear comprising a sun gear (2) connected to a driven central shaft (20), an internal geared wheel (12), a group of first stepped planetary gears (8, 10) and a group of second stepped planetary gears (4, 6). iqh4bman krhho4 bzp fpgk srv ao gtorrt wnq zy 0qqlvyz