With single spur gears, a couple of gears forms a gear stage. In the event that you connect several gear pairs one after another, that is referred to as a multi-stage gearbox. For every gear stage, the direction of rotation between the 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 gear ratio, depending on whether it is a ratio to slower or a ratio to fast. In nearly all applications ratio to slow is required, because the drive torque is certainly multiplied by the overall multiplication factor, unlike the drive velocity.
A multi-stage spur gear can be realized in a technically meaningful method up to gear ratio of approximately 10:1. The reason for this lies in the ratio of the number 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 is getting transmitted. With multi stage planetary gearbox planetary gears a multi-stage gearbox is incredibly easy to realize.
A two-stage gearbox or a three-stage gearbox may be accomplished by merely increasing the distance of the ring equipment and with serial arrangement of a number of individual planet phases. A planetary equipment with a ratio of 20:1 can be manufactured from the individual ratios of 5:1 and 4:1, for example. Rather than the drive shaft the planetary carrier provides the sun equipment, which drives the next planet stage. A three-stage gearbox is definitely obtained by means of increasing the distance of the ring equipment 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 could be combined, which results in a huge number of ratio choices 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 generally 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 decreased. With a ratio of 100:1 the performance is lower than with a ratio of 20:1. To be able to counteract this scenario, the actual fact that the power loss of the drive stage is low must be taken into concern when working with multi-stage gearboxes. That is achieved by reducing gearbox seal friction loss or having a drive stage that is geometrically smaller, for instance. This also decreases the mass inertia, which is 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 combined. Here too the overall multiplication factor is the product of the average person ratios. Depending on the kind of gearing and the kind of bevel gear stage, the drive and the result can rotate in the same path.
Benefits of multi-stage gearboxes:
Wide range of ratios
Continuous 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 (in comparison 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 increase 
in design intricacies of planetary gearbox, mathematical modelling has become complex in character and therefore 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-acceleration planetary gearbox has been offered in this paper, which derives an efficient gear shifting system through designing the transmitting schematic of eight rate gearboxes compounded with four planetary equipment sets. Furthermore, with the help of lever analogy, the transmitting power circulation and relative power efficiency have been identified to analyse the gearbox design. A simulation-based screening and validation have been performed which show the proposed model can be effective and produces satisfactory shift quality through better torque characteristics while shifting the gears. A new heuristic solution to determine suitable 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) because of their benefits of high power density and large reduction in a small volume [1]. The vibration and noise problems of multi-stage planetary gears are usually 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 early literatures [3-5], the vibration structure of some example planetary gears are recognized using lumped-parameter models, but they didn’t provide general conclusions. Lin and Parker [6-7] formally recognized and proved the vibration structure of planetary gears with equal/unequal planet spacing. They analytically classified all planetary gears modes into exactly three classes, 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 ring equipment [9], helical planetary gears [10], herringbone planetary gears [11], and high velocity 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 substance planetary gears of general description including translational examples of freedom, which allows an infinite number of kinematic combinations. They mathematically proved that the modal characteristics of compound planetary gears were analogous to a straightforward, single-stage planetary gear system. Meanwhile, there are various 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 framework of planetary gears, many experts concerned the sensitivity of the organic frequencies and vibration settings to program parameters. They investigated the effect of modal parameters such as for example tooth mesh stiffness, world bearing stiffness and support stiffness on planetary gear 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 compound planetary gears. They proposed closed-form expressions for the eigensensitivities to model parameter variations based on 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 used the structured vibration modes to show that eigenvalue loci of different setting types constantly cross and the ones of the same setting type veer as a model parameter is definitely varied.
However, the majority of of the existing studies just referenced the method used for single-stage planetary gears to investigate 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 examples of freedom in multi-stage planetary gears, more descriptive division of natural frequencies are required to analyze the influence of different system parameters. The objective of this paper is usually to propose an innovative way of examining the coupled modes in multi-stage planetary gears to analyze 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 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 metal, and steel, depending 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, 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 earth gears are installed on a world carrier and engage positively within an internally toothed band equipment. Torque and power are distributed among a number of planet gears. Sun equipment, planet carrier and ring gear may either be traveling, driven or set. Planetary gears are found in automotive structure and shipbuilding, aswell 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 consists of two planet gear pieces, each with three world gears. The ring equipment of the first stage can be coupled to the earth carrier of the next stage. By fixing individual gears, you’ll be able 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 helps prevent the weight from accidentally escaping. A clamping roller freewheel allows free further rotation after the weight offers been released. The weight can be captured by a shock absorber. A transparent protective cover prevents accidental connection with the rotating parts.
To be able to determine the effective torques, the drive 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 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 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 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
drive measurement on different gear stages via 3 bending bars, display via dial gauges
inductive speed sensors
GUNT software for data acquisition via USB below 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
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 degrees of freedom. Planet gears rotate around axes that revolve around a sunlight gear, which spins in place. A ring equipment binds the planets externally and is completely fixed. The concentricity of the earth grouping with sunlight and ring gears means that the torque bears through a straight line. Many power trains are “comfortable” lined up straight, and the absence of offset shafts not merely decreases space, it eliminates the necessity to redirect the energy or relocate other components.
In a simple 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 pressured to orbit as they roll. All of the planets are mounted to an individual rotating member, called a cage, arm, or carrier. As the planet carrier turns, it delivers 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 output powered by two inputs, or an individual input driving two outputs. For example, the differential that drives the axle in an car is 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 theory as parallel-shaft systems.
Even a simple planetary gear train has two inputs; an anchored band gear represents a continuous insight of zero angular velocity.
Designers can go deeper with this “planetary” theme. Compound (as opposed to simple) planetary trains have at least two planet gears attached in series to the same shaft, rotating and orbiting at the same speed while meshing with different gears. Compounded planets can have different tooth figures, as can the gears they mesh with. Having such options significantly expands the mechanical possibilities, and allows more reduction per stage. Compound planetary trains can easily be configured so the planet carrier shaft drives at high acceleration, 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 external gears simultaneously, therefore a ring gear is not essential.
Planet gears, for their size, engage a whole lot of teeth because they circle the sun gear – therefore they can simply accommodate many turns of the driver for each result shaft revolution. To perform a comparable decrease between a standard pinion and gear, a sizable gear will need to mesh with a rather small pinion.
Simple planetary gears generally offer reductions as high as 10:1. Compound planetary systems, which are more elaborate than the simple versions, can offer reductions often higher. There are apparent ways to additional reduce (or as the case may be, increase) swiftness, such as for example connecting planetary levels in series. The rotational output of the initial stage is from the input of another, and the multiple of the individual ratios represents the ultimate reduction.
Another choice is to introduce standard gear reducers right into a planetary teach. For instance, the high-rate power might pass through a typical fixedaxis pinion-and-gear set before the planetary reducer. Such a configuration, called a hybrid, may also be preferred as a simplistic alternative to additional planetary phases, 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 result. If the right angle is needed, bevel or hypoid gears are occasionally mounted on an inline planetary system. Worm and planetary combinations are uncommon since the worm reducer alone delivers such high adjustments in speed.
