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 every gear stage, the path of rotation between the drive shaft and the result shaft is usually reversed. The entire multiplication factor of multi-stage gearboxes is definitely 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 is a ratio to sluggish or a ratio to fast. In the majority of applications ratio to gradual is required, since the drive torque can be multiplied by the entire multiplication aspect, unlike the drive speed.
A multi-stage spur gear can be realized in a technically meaningful way up to gear ratio of around 10:1. The reason behind this lies in the ratio of the number of tooth. From a ratio of 10:1 the generating gearwheel is extremely small. This has a poor effect on the tooth geometry and the torque that’s getting transmitted. With planetary gears a multi-stage gearbox is extremely easy to realize.
A two-stage gearbox or a three-stage gearbox may be accomplished by basically increasing the space of the ring equipment and with serial arrangement of several individual planet stages. A planetary gear with a ratio of 20:1 could be manufactured from the individual ratios of 5:1 and 4:1, for example. Instead of the drive shaft the planetary carrier provides the sun equipment, which drives the following world stage. A three-stage gearbox is obtained by means of increasing the distance of the ring gear and adding another planet stage. A transmitting ratio of 100:1 is obtained using individual ratios of 5:1, 5:1 and 4:1. Basically, all individual ratios could be combined, which outcomes in a big 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 often the same, provided that the ring equipment or housing is fixed.
As the number of equipment stages increases, the efficiency of the overall gearbox is decreased. With a ratio of 100:1 the effectiveness is leaner than with a ratio of 20:1. To be able to counteract this situation, the actual fact that the power loss of the drive stage is certainly low should be taken into consideration 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 certainly advantageous in dynamic applications. Single-stage planetary gearboxes will be the most efficient.
Multi-stage gearboxes can also be realized by combining different types of teeth. With a right angle gearbox a bevel equipment and a planetary gearbox are simply just combined. Here as well the entire multiplication factor may be the product of the individual ratios. Depending on the kind of gearing and the kind of bevel gear stage, the drive and the output can rotate in the same direction.
Benefits of multi-stage gearboxes:
Wide variety of ratios
Constant concentricity with planetary gears
Compact style with high transmission ratios
Combination of different gearbox types possible
Wide variety of uses
Disadvantages of multi-stage gearboxes (compared to single-stage gearboxes):
More complex design
Lower degree of efficiency
The automated 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 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-centered synthesis of three degrees of freedom (DOF) high-rate planetary gearbox provides been offered in this paper, which derives a competent gear shifting mechanism through designing the tranny schematic of eight speed gearboxes compounded with four planetary equipment sets. Furthermore, by making use of lever analogy, the transmitting power flow and relative power performance have been decided to analyse the gearbox style. A simulation-based testing and validation have been performed which show the proposed model is usually effective and produces satisfactory shift quality through better torque characteristics while shifting the gears. A new heuristic method to determine ideal compounding arrangement, predicated on mechanism enumeration, for designing a gearbox layout is proposed here.
Multi-stage planetary gears are trusted in many applications such as automobiles, helicopters and tunneling boring machine (TBM) because of their advantages of high power density and huge reduction in a little quantity [1]. The vibration and noise complications of multi-stage planetary gears are at all times 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 framework of some example planetary gears are recognized using lumped-parameter models, however they didn’t provide general conclusions. Lin and Parker [6-7] formally identified and proved the vibration framework of planetary gears with equivalent/unequal world spacing. They analytically classified all planetary gears settings into exactly three groups, rotational, translational, and planet modes. Parker [8] also investigated the clustering phenomenon of the three setting types. In the recent literatures, the systematic classification of modes had been carried into systems modeled with an elastic continuum ring gear [9], helical planetary gears [10], herringbone planetary gears [11], and high quickness gears with gyroscopic results [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 substance planetary gears of general explanation including translational degrees of freedom, which enables thousands of kinematic combinations. They mathematically proved that the modal features of compound planetary gears were analogous to a straightforward, single-stage planetary gear system. Meanwhile, there are several researchers concentrating on the nonlinear dynamic characteristics of the multi-stage planetary gears for engineering applications, such as for example TBM [15] and wind turbine [16].
According to the aforementioned models and vibration structure of planetary gears, many experts concerned the sensitivity of the organic frequencies and vibration modes to program 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 modes [17-19]. Parker et al. [20-21] mathematically analyzed the effects of design parameters on natural frequencies and vibration modes both for the single-stage and compound planetary gears. They proposed closed-type expressions for the eigensensitivities to model parameter variations based on the well-defined vibration mode properties, and set up the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary gear eigenvalues. They used the structured vibration modes to show that eigenvalue loci of different setting types always cross and the ones of the same mode type veer as a model parameter is usually varied.
However, most of the existing studies only referenced the method used for single-stage planetary gears to analyze the modal features 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 descriptive division of organic frequencies are required to analyze the impact of different system parameters. The aim of this paper is to propose an innovative way of analyzing the coupled modes in multi-stage planetary gears to analyze 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 organic frequencies and vibration settings to both gear 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, based on different application
4. Hight efficiency: 98% efficiency at single reduction, 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 gear is a special kind of gear drive, in which the multiple world gears revolve around a centrally arranged sunlight gear. The planet gears are installed on a world carrier and engage positively within an internally toothed band gear. Torque and power are distributed among several planet gears. Sun gear, planet carrier and band gear may either be driving, driven or fixed. Planetary gears are found 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 models, each with three planet gears. The ring gear of the initial stage is usually coupled to the planet carrier of the next stage. By fixing person gears, it is possible to configure a complete of four different tranny ratios. The gear is accelerated with a cable drum and a variable set of weights. The group of weights is raised with a crank. A ratchet prevents the weight from accidentally escaping. A clamping roller freewheel enables free further rotation following the weight offers been released. The weight is definitely caught by a shock absorber. A transparent protective cover stops multi stage planetary gearbox accidental connection with the rotating 
parts.
To be able to determine the effective torques, the power measurement measures the deflection of bending beams. Inductive speed sensors on all drive gears permit the speeds to end up being measured. The measured values 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 powerful behaviour of a 2-stage planetary gear
three planet gears per stage
four different transmission ratios possible
equipment is accelerated via cable drum and variable 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
power measurement on different equipment levels 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
sunlight gears: 24-tooth, d-pitch circle: 48mm
world 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 kind of planetary gearing involves three sets of gears with different levels of freedom. World gears rotate around axes that revolve around a sunlight gear, which spins in place. A ring equipment binds the planets on the outside and is completely fixed. The concentricity of the earth 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 lack of offset shafts not merely reduces space, it eliminates the need to redirect the power or relocate other elements.
In a simple planetary setup, input power turns the sun gear at high quickness. The planets, spaced around the central axis of rotation, mesh with the sun and also the fixed ring gear, so they are pressured to orbit as they roll. All of the planets are installed to an individual rotating member, called a cage, arm, or carrier. As the earth carrier turns, it delivers low-speed, high-torque output.
A set component isn’t always essential, though. In differential systems every member rotates. Planetary arrangements like this accommodate a single output driven by two inputs, or an individual input driving two outputs. For example, the differential that drives the axle in an car is certainly planetary bevel gearing – the wheel speeds represent two outputs, which must differ to take care of corners. Bevel gear planetary systems operate along the same principle as parallel-shaft systems.
A good simple planetary gear train has two inputs; an anchored ring gear represents a continuous input of zero angular velocity.
Designers can move deeper with this “planetary” theme. Compound (instead of basic) planetary trains possess at least two world gears attached in range to the same shaft, rotating and orbiting at the same swiftness while meshing with different gears. Compounded planets can have got different tooth figures, as can the gears they mesh with. Having this kind of options significantly expands the mechanical possibilities, and allows more decrease per stage. Substance planetary trains can certainly be configured so the world carrier shaft drives at high rate, while the reduction issues from the sun shaft, if the developer prefers this. Another thing about compound planetary systems: the planets can mesh with (and revolve around) both set and rotating external gears simultaneously, hence a ring gear isn’t essential.
Planet gears, because of 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 decrease between a typical pinion and gear, 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 more elaborate than the simple versions, can provide reductions often higher. There are obvious ways to additional reduce (or as the case may be, increase) rate, such as connecting planetary levels in series. The rotational output of the initial stage is linked to the input of another, and the multiple of the individual ratios represents the final reduction.
Another choice is to introduce regular gear reducers right into a planetary train. For instance, the high-velocity power might pass through an ordinary fixedaxis pinion-and-gear set before the planetary reducer. This kind of a configuration, called a hybrid, may also be preferred as a simplistic option to additional planetary stages, or to lower input speeds that are too high for some planetary units to take care of. It also provides an offset between your input and output. If a right angle is needed, bevel or hypoid gears are occasionally attached to an inline planetary system. Worm and planetary combinations are rare since the worm reducer by itself delivers such high changes in speed.
