With single spur gears, a pair of gears forms a gear stage. If you connect several gear pairs one after another, that is known as a multi-stage gearbox. For each gear stage, the direction of rotation between the drive shaft and the result shaft is certainly reversed. The overall multiplication element of multi-stage gearboxes is calculated by multiplying the ratio of each gear stage.
The drive speed is reduced or increased by the factor of the apparatus ratio, depending on whether it’s a ratio to sluggish or a ratio to fast. In the majority of applications ratio to gradual is required, since the drive torque is certainly multiplied by 
the overall multiplication aspect, unlike the drive quickness.
A multi-stage spur gear can be realized in a technically meaningful way up to gear ratio of around 10:1. The reason for this is based on the ratio of the number of the teeth. From a ratio of 10:1 the traveling gearwheel is extremely little. This has a poor effect on the tooth geometry and the torque that is getting transmitted. With planetary gears a multi-stage gearbox is extremely easy to realize.
A two-stage gearbox or a three-stage gearbox can be achieved by merely increasing the length of the ring gear and with serial arrangement of several individual planet stages. A planetary equipment with a ratio of 20:1 could be manufactured from the individual ratios of 5:1 and 4:1, for instance. Rather than the drive shaft the planetary carrier contains the sun equipment, which drives the following world stage. A three-stage gearbox is obtained by means of increasing the length of the ring gear and adding another world stage. A transmission ratio of 100:1 is obtained using individual ratios of 5:1, 5:1 and 4:1. Basically, all person ratios can be combined, which outcomes in a huge number of ratio choices for multi-stage planetary gearboxes. The transmittable torque could be increased using additional planetary gears when doing this. The path of rotation of the drive shaft and the result shaft is generally the same, provided that the ring equipment or housing is fixed.
As the amount of gear stages increases, the efficiency of the overall gearbox is decreased. With a ratio of 100:1 the performance is leaner than with a ratio of 20:1. In order to counteract this situation, the fact that the power loss of the drive stage is usually low must be taken into factor when using multi-stage gearboxes. That is achieved by reducing gearbox seal friction reduction or having a drive stage that is geometrically smaller, for example. This also reduces the mass inertia, which is advantageous in powerful applications. Single-stage planetary gearboxes are the most efficient.
Multi-stage gearboxes may also be realized by combining various kinds of teeth. With a right angle gearbox a bevel equipment and a planetary gearbox are simply combined. Here too the entire multiplication factor may be the product of the individual ratios. Depending on the type of gearing and the type of bevel equipment stage, the drive and the output can rotate in the same path.
Advantages of multi-stage gearboxes:
Wide range of ratios
Constant concentricity with planetary gears
Compact design with high transmission ratios
Combination of different gearbox types possible
Wide range of uses
Disadvantages of multi-stage gearboxes (in comparison to single-stage gearboxes):
More complex design
Lower degree of efficiency
The automatic transmission system is very crucial for the high-speed vehicles, where in fact the planetary or epicyclic gearbox is a typical feature. With the upsurge in design intricacies of planetary gearbox, mathematical modelling is becoming complex in character and for that reason there is a need for modelling of multistage planetary gearbox including the shifting scheme. A random search-based synthesis of three levels of freedom (DOF) high-quickness planetary gearbox has been offered in this paper, which derives an efficient gear shifting system through designing the transmission schematic of eight rate gearboxes compounded with four planetary equipment sets. Furthermore, with the help of lever analogy, the transmission power stream and relative power effectiveness have been established to analyse the gearbox style. A simulation-based assessment and validation have already been performed which show the proposed model is usually efficient and produces satisfactory shift quality through better torque characteristics while shifting the gears. A new heuristic solution to determine appropriate compounding arrangement, predicated on mechanism enumeration, for developing a gearbox design is proposed here.
Multi-stage planetary gears are widely used in many applications such as automobiles, helicopters and tunneling uninteresting machine (TBM) due to their benefits of high power density and huge reduction in a small quantity [1]. The vibration and noise complications of multi-stage planetary gears are always the focus of attention by both academics and engineers [2].
The vibration of simple, single-stage planetary gears has been studied by many researchers. In the first literatures [3-5], the vibration structure of some example planetary gears are identified using lumped-parameter models, however they didn’t give general conclusions. Lin and Parker [6-7] formally identified and proved the vibration framework of planetary gears with equal/unequal world spacing. They analytically classified all planetary gears modes into exactly three types, rotational, translational, and planet settings. Parker [8] also investigated the clustering phenomenon of the three setting types. In the latest literatures, the systematic classification of settings were carried into systems modeled with an elastic continuum band gear [9], helical planetary gears [10], herringbone planetary gears [11], and high speed gears with gyroscopic results [12].
The natural frequencies and vibration modes of multi-stage planetary gears also have received attention. Kahraman [13] established a family group of torsional dynamics models for substance planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic model of compound planetary gears of general description including translational levels of freedom, which allows an infinite number of kinematic combinations. They mathematically proved that the modal characteristics of compound planetary gears had been analogous to a straightforward, single-stage planetary gear program. Meanwhile, there are plenty of researchers focusing on the nonlinear dynamic characteristics of the multi-stage planetary gears for engineering applications, such as for example TBM [15] and wind mill [16].
According to the aforementioned versions and vibration framework of planetary gears, many experts worried the sensitivity of the organic frequencies and vibration settings to system parameters. They investigated the result of modal parameters such as tooth mesh stiffness, planet bearing stiffness and support stiffness on planetary equipment organic frequencies and vibration modes [17-19]. Parker et al. [20-21] mathematically analyzed the consequences of style parameters on natural frequencies and vibration modes both for the single-stage and substance planetary gears. They proposed closed-form expressions for the eigensensitivities to model parameter variations according to the well-defined vibration mode properties, and established the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary gear eigenvalues. They utilized the structured vibration modes showing that eigenvalue loci of different mode types generally cross and those of the same setting type veer as a model parameter is certainly varied.
However, many of the current studies just referenced the method used for single-stage planetary gears to analyze the modal characteristics of multi-stage planetary gears, while the differences between these two types of planetary gears were ignored. Due to the multiple degrees of freedom in multi-stage planetary gears, more detailed division of natural frequencies are required to analyze the impact of different program parameters. The objective of this paper is definitely to propose a novel method of analyzing the coupled settings in multi-stage planetary gears to investigate the parameter sensitivities. Purely rotational degree of freedom models are used to simplify the analytical investigation of equipment vibration while keeping the main dynamic behavior produced by tooth mesh forces. In this paper, sensitivity of natural frequencies and vibration settings to both equipment parameters and coupling shaft parameters of multi-stage planetary gears are studied.
1. Planetary gear sets are available in wide reduction gear ratios
2. Gear arranged can combine the same or different ratios
3. Planetary gear set comes in plastic, sintered steel, and steel, depending on different application
4. Hight efficiency: 98% efficiency at single decrease, 95% at double reduction
5. Planetary gear set torque range: Low torque, middle torque, high torque
6. Easy linking with couplings, input shafts, output shafts
The planetary equipment is a special kind of gear drive, in which the multiple planet gears revolve around a centrally arranged sunlight gear. The planet gears are mounted on a world carrier and engage positively in an internally toothed ring gear. Torque and power are distributed among several planet gears. Sun equipment, planet carrier and band gear may either be traveling, driven or set. Planetary gears are used in automotive building and shipbuilding, as well as for stationary make use of in turbines and general mechanical engineering.
The GL 212 unit allows the investigation of the dynamic behaviour of a two-stage planetary gear. The trainer consists of two planet gear sets, each with three planet gears. The ring equipment of the first stage is usually coupled to the earth carrier of the second stage. By fixing person gears, you’ll be able to configure a complete of four different transmitting ratios. The gear is accelerated via a cable drum and a adjustable group of weights. The group of weights is raised with a crank. A ratchet helps prevent the weight from accidentally escaping. A clamping roller freewheel allows free further rotation after the weight offers been released. The weight is certainly captured by a shock absorber. A transparent protective cover stops accidental contact with the rotating parts.
To be able to determine the effective torques, the pressure measurement measures the deflection of bending beams. Inductive velocity sensors on all drive gears allow the speeds to be measured. The measured ideals are transmitted directly to a Computer via USB. The data acquisition software is roofed. The angular acceleration can be read from the diagrams. Effective mass moments of inertia are determined by the angular acceleration.
investigation of the dynamic behaviour of a 2-stage planetary gear
three world gears per stage
four different transmission ratios possible
gear is accelerated via cable drum and adjustable set of weights
weight raised yourself crank; ratchet prevents accidental release
clamping roller freewheel enables free further rotation after the weight has been released
shock absorber for weight
transparent protective cover
power measurement on different gear stages via 3 bending pubs, display via dial gauges
inductive speed sensors
GUNT software program for data acquisition via USB under Windows 7, 8.1, 10
Technical data
2-stage planetary gear
module: 2mm
sun gears: 24-tooth, d-pitch circle: 48mm
planet gears: 24-tooth, d-pitch circle: 48mm
band gears: 72-tooth, d-pitch circle: 144mm
Drive
set of weights: 5…50kg
max. potential energy: 245,3Nm
Load at standstill
weight forces: 5…70N
Measuring ranges
speed: 0…2000min-1
230V, 50Hz, 1 phase
230V, 60Hz, 1 stage; 120V, 60Hz, 1 phase
UL/CSA optional
he most basic form of planetary gearing involves three sets of gears with different examples of freedom. World gears rotate around axes that revolve around a sun gear, which spins in place. A ring gear binds the planets externally and is completely fixed. The concentricity of the planet grouping with the sun and ring gears implies that the torque bears through a straight series. Many power trains are “comfortable” lined up straight, and the lack of offset shafts not merely reduces space, it eliminates the need to redirect the power or relocate other parts.
In a straightforward planetary setup, input power turns sunlight gear at high speed. The planets, spaced around the central axis of rotation, mesh with the sun as well as the fixed ring equipment, so they are forced to orbit as they roll. All of the planets are mounted to a single rotating member, known as a cage, arm, or carrier. As the planet carrier turns, it provides low-speed, high-torque output.
A set component isn’t often essential, though. In differential systems every member rotates. Planetary arrangements such as this accommodate a single output driven by two inputs, or a single input driving two outputs. For example, the differential that drives the axle in an car can be planetary bevel gearing – the wheel speeds represent two outputs, which must differ to take care of corners. Bevel equipment planetary systems operate along the same basic principle as parallel-shaft systems.
Even a simple planetary gear train has two inputs; an anchored band gear represents a constant insight of zero angular velocity.
Designers can move deeper with this “planetary” theme. Compound (as opposed to basic) planetary trains possess at least two planet gears attached in collection to the same shaft, rotating and orbiting at the same swiftness while meshing with different gears. Compounded planets can possess different tooth numbers, as can the gears they mesh with. Having this kind of options greatly expands the mechanical possibilities, and allows more decrease per stage. Compound planetary trains can simply be configured so the planet carrier shaft drives at high quickness, while the reduction issues from sunlight shaft, if the developer prefers this. One more thing about substance planetary systems: the planets can mesh with (and revolve around) both fixed and rotating exterior gears simultaneously, hence a ring gear is not essential.
Planet gears, because of their size, engage a lot of teeth as they circle the sun equipment – therefore they can easily accommodate many turns of the driver for each result shaft revolution. To perform a comparable reduction between a multi stage planetary gearbox standard pinion and equipment, a sizable gear will need to mesh with a rather small pinion.
Simple planetary gears generally offer reductions as high as 10:1. Substance planetary systems, which are more elaborate compared to the simple versions, can offer reductions many times higher. There are obvious ways to additional decrease (or as the case may be, increase) acceleration, such as for example connecting planetary levels in series. The rotational result of the initial stage is from the input of the next, and the multiple of the average person ratios represents the final reduction.
Another option is to introduce regular gear reducers right into a planetary train. For example, the high-quickness power might pass through an ordinary fixedaxis pinion-and-gear set prior to the planetary reducer. Such a configuration, called a hybrid, is sometimes preferred as a simplistic alternative to additional planetary phases, or to lower insight speeds that are too high for a few planetary units to handle. It also has an offset between the input and result. If the right angle is necessary, bevel or hypoid gears are sometimes mounted on an inline planetary system. Worm and planetary combinations are rare because the worm reducer by itself delivers such high changes in speed.
