With single spur gears, a set of gears forms a gear stage. If you connect several gear pairs one after another, this is known as a multi-stage gearbox. For every gear stage, the path of rotation between the drive shaft and the output shaft is usually reversed. The entire multiplication aspect of multi-stage gearboxes is usually 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 is a ratio to sluggish or a ratio to fast. In nearly all applications ratio to sluggish is required, because the drive torque is certainly multiplied by the entire multiplication aspect, unlike the drive quickness.
A multi-stage spur gear could be realized in a technically meaningful method up to gear ratio of approximately 10:1. The reason behind this is based on the ratio of the number of the teeth. From a ratio of 10:1 the generating gearwheel is extremely little. This has a negative influence on the tooth geometry and the torque that is becoming transmitted. With planetary gears a multi-stage gearbox is incredibly easy to realize.
A two-stage gearbox or a three-stage gearbox may be accomplished by simply increasing the distance of the ring equipment and with serial arrangement of several individual planet stages. A planetary equipment with a ratio of 20:1 could be manufactured from the average person ratios of 5:1 and 4:1, for instance. Instead of the drive shaft the planetary carrier contains the sun equipment, which drives the following world stage. A three-stage gearbox is obtained by way of increasing the distance of the ring gear and adding another world stage. A transmitting ratio of 100:1 is obtained using person ratios of 5:1, 5:1 and 4:1. Basically, all individual ratios can be combined, which outcomes in a large number of ratio options for multi-stage planetary gearboxes. The transmittable torque could be increased using additional planetary gears when carrying out this. The direction of rotation of the drive shaft and the output shaft is constantly the same, provided that the ring equipment or housing is fixed.
As the amount of gear stages increases, the efficiency of the entire gearbox is reduced. With a ratio of 100:1 the effectiveness is leaner than with a ratio of 20:1. To be able to counteract this circumstance, the fact that the power loss of the drive stage is low must be taken into concern when working with multi-stage gearboxes. That is attained by reducing gearbox seal friction reduction or having a drive stage that is geometrically smaller, for instance. This also reduces the mass inertia, which is advantageous in dynamic applications. Single-stage planetary gearboxes are the most efficient.
Multi-stage gearboxes may also be realized by combining different types of teeth. With the right angle gearbox a bevel gear and a planetary gearbox are simply combined. Here too the overall multiplication factor is the product of the individual ratios. Depending on the kind of gearing and the type of bevel gear stage, the drive and the output can rotate in the same path.
Advantages of multi-stage gearboxes:
Wide variety of ratios
Constant concentricity with planetary gears
Compact design with high transmission ratios
Mix of different gearbox types possible
Wide range of uses
Disadvantages of multi-stage gearboxes (in comparison to single-stage gearboxes):
More complex design
Lower amount of efficiency
The automatic transmission system is very crucial for the high-speed vehicles, where the planetary or epicyclic gearbox is a standard feature. With the increase in design intricacies of planetary gearbox, mathematical modelling is becoming complex in nature and for that reason there is a dependence on modelling of multistage planetary gearbox like the shifting scheme. A random search-centered synthesis of three degrees of freedom (DOF) high-rate planetary gearbox provides been provided in this paper, which derives a competent gear shifting mechanism through designing the transmission schematic of eight acceleration gearboxes compounded with four planetary equipment sets. Furthermore, by using lever analogy, the tranny power flow and relative power performance have been established to analyse the gearbox design. A simulation-based tests and validation have already been performed which show the proposed model is definitely efficient and produces satisfactory shift quality through better torque characteristics while shifting the gears. A fresh heuristic method to determine suitable compounding arrangement, based on mechanism enumeration, for developing a gearbox design is proposed here.
Multi-stage planetary gears are widely used in many applications such as for example automobiles, helicopters and tunneling boring machine (TBM) due to their benefits of high power density and large reduction in a small quantity [1]. The vibration and noise problems of multi-stage planetary gears are constantly the focus of interest 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 determined using lumped-parameter models, but they didn’t give general conclusions. Lin and Parker [6-7] formally determined and proved the vibration structure of planetary gears with equivalent/unequal world spacing. They analytically classified all planetary gears settings into exactly three categories, rotational, translational, and planet settings. Parker [8] also investigated the clustering phenomenon of the three mode types. In the latest literatures, the systematic classification of modes had been carried into systems modeled with an elastic continuum band gear [9], helical planetary gears [10], herringbone planetary gears [11], and high acceleration gears with gyroscopic effects [12].
The organic frequencies and vibration settings of multi-stage planetary gears have also received attention. Kahraman [13] founded 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 enables thousands of kinematic combinations. They mathematically proved that the modal features of compound planetary gears were analogous to a simple, single-stage planetary gear program. Meanwhile, there are plenty of researchers concentrating on the nonlinear dynamic features of the multi-stage planetary gears for engineering applications, such as for example TBM [15] and wind turbine [16].
According to the aforementioned versions and vibration structure of planetary gears, many researchers concerned the sensitivity of the organic frequencies and vibration settings to program parameters. They investigated the result of modal parameters such as tooth mesh stiffness, planet bearing stiffness and support stiffness on planetary gear natural frequencies and vibration settings [17-19]. Parker et al. [20-21] mathematically analyzed the consequences of design parameters on organic frequencies and vibration settings both for the single-stage and compound planetary gears. They proposed closed-type expressions for the eigenmulti stage planetary gearbox sensitivities to model parameter variants based on the well-defined vibration mode properties, and founded the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary equipment eigenvalues. They used 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 varied.
However, the majority of of the existing studies just referenced the method used for single-stage planetary gears to investigate the modal characteristics of multi-stage planetary gears, as the differences between these two types of planetary gears were ignored. Because of the multiple examples of freedom in multi-stage planetary gears, more descriptive division of organic frequencies are required to analyze the influence of different system parameters. The aim of this paper can be to propose a novel method of analyzing the coupled settings in multi-stage planetary gears to analyze the parameter sensitivities. Purely rotational degree of freedom models are accustomed to simplify the analytical investigation of gear vibration while keeping the primary dynamic behavior produced by tooth mesh forces. In this paper, sensitivity of organic frequencies and vibration settings to both equipment parameters and coupling shaft parameters of multi-stage planetary gears are studied.
1. Planetary gear sets can be found in wide reduction gear ratios
2. Gear established can combine the same or different ratios
3. Planetary gear set comes in plastic, sintered metal, and steel, based 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, result shafts
The planetary equipment is a special type of gear drive, where the multiple planet gears revolve around a centrally arranged sun gear. The earth gears are installed on a planet carrier and engage positively within an internally toothed band gear. Torque and power are distributed among several planet gears. Sun equipment, planet carrier and band equipment may either be generating, driven or fixed. 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 includes two planet gear pieces, each with three planet gears. The ring equipment of the initial stage can be coupled to the planet carrier of the second stage. By fixing person gears, it is possible to configure a total of four different tranny ratios. The gear is accelerated with a cable drum and a variable set of weights. The set of weights is raised with a crank. A ratchet prevents the weight from accidentally escaping. A clamping roller freewheel allows free further rotation after the weight offers been released. The weight is usually caught by a shock absorber. A transparent protective cover stops accidental connection with the rotating parts.
In order 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 values are transmitted right to a Computer via USB. The info acquisition software is roofed. The angular acceleration can be read from the diagrams. Effective mass occasions of inertia are determined by the angular acceleration.
investigation of the dynamic behaviour of a 2-stage planetary gear
three planet gears per stage
four different transmission ratios possible
gear is accelerated via cable drum and adjustable set of weights
weight raised by hand crank; ratchet prevents accidental release
clamping roller freewheel allows free further rotation after the weight has been released
shock absorber for weight
transparent protective cover
pressure measurement on different gear phases via 3 bending bars, display via dial gauges
inductive speed sensors
GUNT software for data acquisition via USB under Windows 7, 8.1, 10
Technical data
2-stage planetary gear
module: 2mm
sunlight gears: 24-tooth, d-pitch circle: 48mm
planet gears: 24-tooth, d-pitch circle: 48mm
ring 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 levels of freedom. World gears rotate around axes that revolve around a sun gear, which spins set up. A ring gear binds the planets externally and is completely set. The concentricity of the planet grouping with the sun and ring gears means that the torque carries through a straight collection. Many power trains are “comfortable” lined up straight, and the lack of offset shafts not only reduces 
space, it eliminates the necessity to redirect the energy or relocate other elements.
In a simple planetary setup, input power turns the sun gear at high swiftness. The planets, spaced around the central axis of rotation, mesh with sunlight and also the fixed ring gear, so they are forced to orbit because they roll. All of the planets are mounted to an individual rotating member, called a cage, arm, or carrier. As the earth carrier turns, it provides low-speed, high-torque output.
A fixed component isn’t often essential, though. In differential systems every member rotates. Planetary arrangements such as this accommodate a single output powered by two inputs, or a single input driving two outputs. For example, the differential that drives the axle within an automobile is planetary bevel gearing – the wheel speeds represent two outputs, which must differ to handle corners. Bevel gear planetary systems operate along the same theory as parallel-shaft systems.
Even a simple planetary gear train provides two inputs; an anchored ring gear represents a constant insight of zero angular velocity.
Designers can proceed deeper with this “planetary” theme. Compound (as opposed to basic) planetary trains have at least two planet gears attached in range to the same shaft, rotating and orbiting at the same quickness while meshing with different gears. Compounded planets can have different tooth amounts, as can the gears they mesh with. Having such options greatly expands the mechanical options, and allows more reduction per stage. Substance planetary trains can simply be configured so the world carrier shaft drives at high velocity, while the reduction issues from sunlight shaft, if the designer prefers this. One more thing about compound planetary systems: the planets can mesh with (and revolve around) both set and rotating exterior gears simultaneously, hence a ring gear isn’t essential.
Planet gears, for their size, engage a whole lot of teeth because they circle the sun gear – therefore they can simply accommodate several turns of the driver for each result shaft revolution. To perform a comparable reduction between a standard pinion and equipment, a sizable gear will have to mesh with a fairly small pinion.
Basic planetary gears generally offer reductions as high as 10:1. Compound planetary systems, which are far more elaborate compared to the simple versions, can offer reductions often higher. There are apparent ways to additional reduce (or as the case may be, increase) acceleration, such as connecting planetary phases in series. The rotational output of the initial stage is from the input of another, and the multiple of the average person ratios represents the final reduction.
Another option is to introduce standard gear reducers into a planetary teach. For example, the high-speed power might go through a typical fixedaxis pinion-and-gear set before the planetary reducer. This kind of a configuration, known as a hybrid, may also be preferred as a simplistic alternative to additional planetary levels, or to lower input speeds that are too high for a few planetary units to handle. It also has an offset between the input and result. If a right angle is necessary, bevel or hypoid gears are occasionally mounted on an inline planetary system. Worm and planetary combinations are uncommon because the worm reducer alone delivers such high changes in speed.