With single spur gears, a set of gears forms a gear stage. In the event that you connect several gear pairs one after another, that is known as a multi-stage gearbox. For every gear stage, the direction of rotation between the drive shaft and the output shaft is usually reversed. The entire multiplication aspect 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 gear ratio, depending on whether it’s a ratio to slower or a ratio to fast. In the majority of applications ratio to sluggish is required, because the drive torque is certainly multiplied by the overall multiplication element, unlike the drive velocity.
A multi-stage spur gear could be realized in a technically meaningful method up to gear ratio of around 10:1. The reason behind this is based on the ratio of the amount of the teeth. From a ratio of 10:1 the driving gearwheel is extremely little. This has a poor effect on the tooth geometry and the torque that’s getting 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 merely increasing the space of the ring gear and with serial arrangement of many individual planet levels. A planetary gear with a ratio of 20:1 could be manufactured from the average person ratios of 5:1 and 4:1, for example. Instead of the drive shaft the planetary carrier provides the sun equipment, which drives the next world stage. A three-stage gearbox is obtained by way of increasing the space of the ring gear and adding another world stage. A transmission ratio of 100:1 is obtained using person ratios of 5:1, 5:1 and 4:1. Basically, all person ratios can be combined, which outcomes in a sizable number of ratio choices for multi-stage planetary gearboxes. The transmittable torque can be increased using additional planetary gears when performing this. The direction of rotation of the drive shaft and the output shaft is constantly the same, provided that the ring equipment or casing is fixed.
As the amount of gear stages increases, the efficiency of the overall gearbox is decreased. 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 account when using multi-stage gearboxes. This is achieved by reducing gearbox seal friction loss or having a drive stage that is multi stage planetary gearbox geometrically smaller, for instance. This also decreases the mass inertia, which is certainly advantageous in powerful applications. Single-stage planetary gearboxes are the most efficient.
Multi-stage gearboxes may also be realized by combining different types of teeth. With a right angle gearbox a bevel gear and a planetary gearbox are simply just combined. Here too the entire multiplication factor is the product of the individual ratios. Depending on the type of gearing and the type of bevel gear stage, the drive and the output can rotate in the same direction.
Benefits of multi-stage gearboxes:
Wide range of ratios
Continuous concentricity with planetary gears
Compact style 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 quite crucial for the high-speed vehicles, where the planetary or epicyclic gearbox is a typical feature. With the upsurge in design intricacies of planetary gearbox, mathematical modelling has become complex in nature and therefore there is a need for modelling of multistage planetary gearbox including the shifting scheme. A random search-centered synthesis of three degrees of freedom (DOF) high-swiftness planetary gearbox provides been shown in this paper, which derives a competent gear shifting mechanism through designing the transmission schematic of eight swiftness gearboxes compounded with four planetary equipment sets. Furthermore, by making use of lever analogy, the transmission power flow and relative power effectiveness have been motivated to analyse the gearbox design. A simulation-based assessment and validation have been performed which display the proposed model can be efficient and produces satisfactory shift quality through better torque characteristics while shifting the gears. A new heuristic solution to determine suitable compounding arrangement, based on mechanism enumeration, for designing a gearbox design is proposed here.
Multi-stage planetary gears are widely used in many applications such as automobiles, helicopters and tunneling boring machine (TBM) due to their benefits of high power density and large reduction in a little volume [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 recognized using lumped-parameter models, but they didn’t provide general conclusions. Lin and Parker [6-7] formally discovered and proved the vibration structure of planetary gears with the same/unequal planet spacing. They analytically classified all planetary gears settings into exactly three types, rotational, translational, and world modes. Parker [8] also investigated the clustering phenomenon of the three mode types. In the recent literatures, the systematic classification of modes were 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 of torsional dynamics versions for substance planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic model of compound planetary gears of general explanation including translational degrees of freedom, which enables thousands 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 TBM [15] and wind mill [16].
Based on the aforementioned 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 effect of modal parameters such as 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 effects of design parameters on natural frequencies and vibration settings both for the single-stage and substance planetary gears. They proposed closed-type expressions for the eigensensitivities to model parameter variations based on the well-defined vibration setting properties, and set up the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary equipment eigenvalues. They utilized the organized vibration modes to show that eigenvalue loci of different mode types at all times cross and those of the same mode type veer as a model parameter is certainly varied.
However, most of the existing studies only referenced the technique used for single-stage planetary gears to analyze the modal features of multi-stage planetary gears, as the differences between both of these types of planetary gears were ignored. Due to the multiple degrees of freedom in multi-stage planetary gears, more descriptive division of natural frequencies are required to analyze the influence of different system parameters. The aim of this paper is certainly to propose a novel method of analyzing the coupled modes in multi-stage planetary gears to investigate the parameter sensitivities. Purely rotational amount of freedom models are used 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 settings to both gear 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 steel, and steel, based on different application
4. Hight efficiency: 98% efficiency at single decrease, 95% at double reduction
5. Planetary gear established 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 world gears revolve around a centrally arranged sunlight gear. The earth gears are mounted on a world carrier and engage positively in an internally toothed ring equipment. Torque and power are distributed among many planet gears. Sun gear, planet carrier and band equipment may either be driving, driven or fixed. Planetary gears are found in automotive structure and shipbuilding, aswell 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 models, each with three planet gears. The ring equipment of the first stage is definitely coupled to the earth carrier of the second stage. By fixing person gears, you’ll be able to configure a complete of four different transmission ratios. The gear is accelerated via a cable drum and a variable set of weights. The set of weights is raised with a crank. A ratchet stops the weight from accidentally escaping. A clamping roller freewheel allows free further rotation after the weight offers been released. The weight can be caught by a shock absorber. A transparent protective cover stops accidental contact with the rotating parts.
In order to determine the effective torques, the force measurement measures the deflection of bending beams. Inductive velocity sensors on all drive gears permit the speeds to end up being measured. The measured ideals are transmitted directly to a PC via USB. The data acquisition software is included. The angular acceleration can be read from the diagrams. Effective mass occasions of inertia are dependant on the angular acceleration.
investigation of the powerful 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 by hand 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
force measurement on different equipment stages via 3 bending pubs, 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
sun 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 phase; 120V, 60Hz, 1 phase
UL/CSA optional
he most basic type of planetary gearing involves three sets of gears with different degrees of freedom. Planet gears rotate around axes that revolve around a sunlight gear, which spins set up. A ring gear binds the planets externally and is completely set. The concentricity of the planet grouping with sunlight and ring gears means that the torque bears through a straight series. Many power trains are “comfortable” lined up straight, and the absence of offset shafts not only decreases space, it eliminates the need to redirect the power or relocate other elements.
In a simple planetary setup, input power turns sunlight 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 installed to a single 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 like this accommodate a single result powered by two inputs, or a single input traveling two outputs. For example, the differential that drives the axle in an car is usually planetary bevel gearing – the wheel speeds represent 
two outputs, which must differ to handle corners. Bevel gear planetary systems operate along the same basic principle as parallel-shaft systems.
Even a simple planetary gear train has two inputs; an anchored ring gear represents a constant insight of zero angular velocity.
Designers can proceed deeper with this “planetary” theme. Compound (instead of simple) planetary trains possess at least two world gears attached in collection to the same shaft, rotating and orbiting at the same rate while meshing with different gears. Compounded planets can have got different tooth figures, as can the gears they mesh with. Having such options significantly expands the mechanical opportunities, and allows more reduction per stage. Substance planetary trains can easily be configured so the world carrier shaft drives at high quickness, while the reduction problems from the sun shaft, if the designer prefers this. Another thing about compound planetary systems: the planets can mesh with (and revolve around) both fixed and rotating exterior gears simultaneously, hence a ring gear isn’t essential.
Planet gears, for his or her size, engage a whole lot of teeth because they circle the sun gear – therefore they can simply accommodate numerous turns of the driver for every result shaft revolution. To perform a comparable reduction between a typical pinion and gear, a sizable gear will have to mesh with a fairly 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 further decrease (or as the case could be, increase) swiftness, such as for example connecting planetary levels in series. The rotational output of the 1st stage is from the input of the next, and the multiple of the individual ratios represents the final reduction.
Another choice is to introduce regular gear reducers right into a planetary teach. For instance, the high-rate power might pass through a typical fixedaxis pinion-and-gear set prior to the planetary reducer. This kind of a configuration, called a hybrid, may also be favored as a simplistic option to additional planetary levels, or to lower insight speeds that are too much for some planetary units to handle. It also has an offset between the input and output. If the right angle is needed, bevel or hypoid gears are occasionally attached to an inline planetary program. Worm and planetary combinations are rare since the worm reducer alone delivers such high adjustments in speed.
