With single spur gears, a set of gears forms a gear stage. If you connect several equipment pairs one after another, that is referred to as a multi-stage gearbox. For every gear stage, the path of rotation between your drive shaft and the output shaft is definitely reversed. The overall multiplication factor of multi-stage gearboxes can be calculated by multiplying the ratio of every gear stage.
The drive speed is reduced or increased by the factor of the apparatus ratio, depending on whether it’s a ratio to slower or a ratio to fast. In nearly all applications ratio to slow is required, because the drive torque can be multiplied by the overall multiplication element, unlike the drive quickness.
A multi-stage spur gear can be realized in a technically meaningful way up to gear ratio of approximately 10:1. The reason behind this lies in the ratio of the amount of the teeth. From a ratio of 10:1 the generating gearwheel is extremely little. This has a poor influence on the tooth geometry and the torque that’s being transmitted. With planetary gears a multi-stage gearbox is incredibly easy to realize.
A two-stage gearbox or a three-stage gearbox can be achieved by just increasing the length of the ring gear and with serial arrangement of many individual planet levels. A planetary gear with a ratio of 20:1 can 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 gear, which drives the following planet stage. A three-stage gearbox is definitely obtained by way of increasing the space 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 could be combined, which outcomes in a sizable number of ratio options for multi-stage planetary gearboxes. The transmittable torque could be increased using extra planetary gears when carrying out this. The path of rotation of the drive shaft and the output shaft is at all times the same, provided that the ring equipment or housing is fixed.
As the number of gear stages increases, the efficiency of the entire gearbox is reduced. With a ratio of 100:1 the efficiency is leaner than with a ratio of 20:1. In order to counteract this scenario, the fact that the power loss of the drive stage can be low should be taken into consideration when using multi-stage gearboxes. That is attained by reducing gearbox seal friction reduction or having a drive stage that’s geometrically smaller, for instance. This also decreases the mass inertia, which is usually advantageous in dynamic applications. Single-stage planetary gearboxes will be the most efficient.
Multi-stage gearboxes may also be realized by combining different types of teeth. With a right position gearbox a bevel gear and a planetary gearbox are simply just combined. Here as well the entire multiplication factor may be the product of the average person ratios. Depending on the type of gearing and the kind of bevel equipment stage, the drive and the result can rotate in the same path.
Benefits 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 variety 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 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-based synthesis of three degrees of freedom (DOF) high-velocity planetary gearbox has been shown in this paper, which derives a competent gear shifting system through designing the tranny schematic of eight speed gearboxes compounded with four planetary gear sets. Furthermore, with the aid of lever analogy, the transmission power flow and relative power effectiveness have been established to analyse the gearbox design. A simulation-based screening and validation have been performed 
which display the proposed model is usually effective and produces satisfactory change 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 layout 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 large reduction in a little quantity [1]. The vibration and noise complications of multi-stage planetary gears are generally 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 early literatures [3-5], the vibration framework of some example planetary gears are determined 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 equivalent/unequal planet spacing. They analytically categorized all planetary gears settings into exactly three categories, rotational, translational, and world modes. Parker [8] also investigated the clustering phenomenon of the three setting types. In the latest literatures, the systematic classification of settings had been carried into systems modeled with an elastic continuum ring gear [9], helical planetary gears [10], herringbone planetary gears [11], and high rate gears with gyroscopic results [12].
The natural frequencies and vibration modes of multi-stage planetary gears also have 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 explanation including translational examples of freedom, which allows thousands of kinematic combinations. They mathematically proved that the modal characteristics of substance planetary gears had been analogous to a straightforward, single-stage planetary gear system. Meanwhile, there are various 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 multi stage planetary gearbox versions and vibration framework of planetary gears, many experts concerned the sensitivity of the natural frequencies and vibration settings to system parameters. They investigated the result of modal parameters such as for example tooth mesh stiffness, world bearing stiffness and support stiffness on planetary equipment organic frequencies and vibration settings [17-19]. Parker et al. [20-21] mathematically analyzed the consequences of style parameters on organic frequencies and vibration modes both for the single-stage and compound planetary gears. They proposed closed-type expressions for the eigensensitivities 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 gear eigenvalues. They used the structured vibration modes showing that eigenvalue loci of different setting types usually cross and those of the same mode type veer as a model parameter can be varied.
However, the majority of of the existing studies just referenced the technique used for single-stage planetary gears to analyze the modal features of multi-stage planetary gears, as the differences between these two types of planetary gears had been ignored. Due to the multiple levels of freedom in multi-stage planetary gears, more descriptive division of organic frequencies must analyze the influence of different program parameters. The objective of this paper is to propose an innovative way of examining the coupled settings in multi-stage planetary gears to investigate the parameter sensitivities. Purely rotational amount 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 natural frequencies and vibration modes 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 metal, and steel, based on different application
4. Hight efficiency: 98% efficiency at single reduction, 95% at double reduction
5. Planetary gear established torque range: Low torque, middle torque, high torque
6. Easy linking with couplings, input shafts, result shafts
The planetary equipment is a special kind of gear drive, where the multiple world gears revolve around a centrally arranged sun gear. The earth gears are mounted on a planet carrier and engage positively in an internally toothed ring equipment. Torque and power are distributed among many planet gears. Sun gear, planet carrier and ring gear may either be generating, driven or set. Planetary gears are used in automotive building and shipbuilding, as well as for stationary use 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 units, each with three planet gears. The ring equipment of the initial stage is certainly coupled to the planet carrier of the next stage. By fixing person gears, you’ll be able to configure a total of four different transmitting ratios. The apparatus is accelerated with a cable drum and a adjustable set of weights. The group of weights is raised with a crank. A ratchet helps prevent the weight from accidentally escaping. A clamping roller freewheel enables free further rotation after the weight provides been released. The weight is usually caught by a shock absorber. A transparent protective cover stops accidental contact with the rotating parts.
To be able to determine the effective torques, the force measurement measures the deflection of bending beams. Inductive speed sensors on all drive gears permit the speeds to become measured. The measured values are transmitted directly to a Computer via USB. The info acquisition software is roofed. The angular acceleration could be read from the diagrams. Effective mass occasions of inertia are dependant on the angular acceleration.
investigation of the dynamic behaviour of a 2-stage planetary gear
three planet gears per stage
four different transmission ratios possible
equipment is accelerated via cable drum and adjustable set of weights
weight raised by hand crank; ratchet prevents accidental release
clamping roller freewheel enables free further rotation following the weight has been released
shock absorber for weight
transparent protective cover
force measurement on different equipment phases via 3 bending pubs, display via dial gauges
inductive speed sensors
GUNT software program for data acquisition via USB below Windows 7, 8.1, 10
Technical data
2-stage planetary gear
module: 2mm
sun gears: 24-tooth, d-pitch circle: 48mm
world gears: 24-tooth, d-pitch circle: 48mm
band gears: 72-tooth, d-pitch circle: 144mm
Drive
group 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 kind 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 equipment binds the planets externally and is completely fixed. 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 components.
In a simple planetary setup, input power turns the sun gear at high speed. The planets, spaced around the central axis of rotation, mesh with sunlight and also the fixed ring equipment, so they are forced to orbit as they roll. All the planets are installed to a single rotating member, called a cage, arm, or carrier. As the planet carrier turns, it provides low-speed, high-torque output.
A fixed component isn’t constantly essential, though. In differential systems every member rotates. Planetary arrangements like this accommodate a single result driven by two inputs, or an individual input generating 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 equipment planetary systems operate along the same 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 proceed deeper with this “planetary” theme. Compound (instead of basic) planetary trains possess at least two world gears attached in line to the same shaft, rotating and orbiting at the same rate while meshing with different gears. Compounded planets can have got different tooth amounts, as can the gears they mesh with. Having this kind of options greatly expands the mechanical possibilities, and allows more decrease per stage. Substance planetary trains can simply be configured therefore the world carrier shaft drives at high speed, while the reduction problems from the sun shaft, if the developer prefers this. One more thing about substance planetary systems: the planets can mesh with (and revolve around) both set and rotating external 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 simply accommodate several turns of the driver for each result shaft revolution. To perform a comparable reduction between a typical pinion and gear, a sizable gear will need to mesh with a fairly small pinion.
Simple planetary gears generally provide reductions as high as 10:1. Substance planetary systems, which are more elaborate than 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 phases in series. The rotational output of the 1st stage is from the input of the next, and the multiple of the average person ratios represents the ultimate reduction.
Another choice is to introduce regular gear reducers right into a planetary teach. For example, the high-quickness power might go through an ordinary 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 option to additional planetary phases, or to lower input speeds that are too high for a few planetary units to take care of. It also provides an offset between the input and output. If the right angle is necessary, bevel or hypoid gears are occasionally mounted on an inline planetary program. Worm and planetary combinations are rare since the worm reducer alone delivers such high changes in speed.