With single spur gears, a set of gears forms a gear stage. If you connect several equipment pairs one after another, this is known as a multi-stage gearbox. For every gear stage, the path of rotation between your drive shaft and the result shaft can be reversed. The overall multiplication aspect of multi-stage gearboxes is certainly 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 sluggish is required, since the drive torque is usually multiplied by the overall multiplication aspect, unlike the drive speed.
A multi-stage spur gear can be realized in a technically meaningful way up to a gear ratio of around 10:1. The reason behind this lies in the ratio of the number of teeth. From a ratio of 10:1 the traveling gearwheel is extremely small. This has a poor effect on the tooth geometry and the torque that is being transmitted. With planetary gears a multi-stage gearbox is extremely easy to realize.
A two-stage gearbox or a three-stage gearbox can be achieved by just increasing the distance of the ring equipment and with serial arrangement of several individual planet phases. A planetary equipment 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 contains the sun equipment, which drives the next world stage. A three-stage gearbox is definitely obtained by means of increasing the length of the ring equipment and adding another planet stage. A transmission ratio of 100:1 is obtained using individual ratios of 5:1, 5:1 and 4:1. Basically, all individual ratios can be combined, which results in a sizable number of ratio choices for multi-stage planetary gearboxes. The transmittable torque can be increased using additional planetary gears when carrying out this. The direction of rotation of the drive shaft and the result shaft is usually the same, so long as the ring gear or casing is fixed.
As the number 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 actual fact that the power lack of the drive stage can be low must be taken into concern when working with multi-stage gearboxes. That is attained 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 usually advantageous in dynamic applications. Single-stage planetary gearboxes will be the most efficient.
Multi-stage gearboxes may also be realized by combining various kinds of teeth. With a 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 direction.
Advantages of multi-stage gearboxes:
Wide range of ratios
Constant concentricity with planetary gears
Compact design with high transmission ratios
Mix 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 very crucial for the high-speed vehicles, where the planetary or epicyclic gearbox is a standard feature. With the upsurge in design intricacies of planetary gearbox, mathematical modelling has become complex in nature and therefore there is a dependence on modelling of multistage planetary gearbox like the shifting scheme. A random search-based synthesis of three examples of freedom (DOF) high-quickness planetary gearbox offers been presented in this paper, which derives an efficient gear shifting system through designing the tranny schematic of eight velocity gearboxes compounded with four planetary gear sets. Furthermore, with the aid of lever analogy, the tranny power stream and relative power effectiveness have been motivated to analyse the gearbox style. A simulation-based examining and validation have been performed which show the proposed model is definitely effective and produces satisfactory change quality through better torque characteristics while shifting the gears. A fresh heuristic method to determine ideal 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 automobiles, helicopters and tunneling boring machine (TBM) because of their benefits of high power density and huge reduction in a little quantity [1]. The vibration and noise problems of multi-stage planetary gears are usually 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 first literatures [3-5], the vibration structure of some example planetary gears are identified using lumped-parameter models, however they didn’t provide 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 classes, rotational, translational, and world settings. Parker [8] also investigated the clustering phenomenon of the three setting types. In the latest literatures, the systematic classification of settings were carried into systems modeled with an elastic continuum band equipment [9], helical planetary gears [10], herringbone planetary gears [11], and high rate gears with gyroscopic effects [12].
The organic frequencies and vibration modes of multi-stage planetary gears have also received attention. Kahraman [13] founded a family of torsional dynamics versions for compound planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic model of substance planetary gears of general explanation including translational examples of freedom, which enables thousands of kinematic combinations. They mathematically proved that the modal features of compound planetary gears had been analogous to a simple, single-stage planetary gear system. Meanwhile, there are many researchers focusing 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 framework of planetary gears, many researchers 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, planet 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 settings both for the single-stage and substance planetary gears. They proposed closed-form expressions for the eigensensitivities to model parameter variants 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 structured vibration modes showing that eigenvalue loci of different mode types always cross and the ones of the same setting type veer as a model parameter is usually varied.
However, many of the existing studies only referenced the method used for single-stage planetary gears to investigate the modal features of multi-stage planetary gears, as the differences between these two types of planetary gears had been ignored. Because of the multiple examples of freedom in multi-stage planetary gears, more descriptive division of organic frequencies must analyze the impact of different program parameters. The objective of this paper can be 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 main dynamic behavior generated 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 are available in wide reduction gear ratios
2. Gear set can combine the same or different ratios
3. Planetary gear set is available 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 arranged torque range: Low torque, middle torque, high torque
6. Easy connecting with couplings, input shafts, output shafts
The planetary gear is a special kind of gear drive, in which the multiple planet gears revolve around a centrally arranged sun gear. The planet gears are mounted on a planet carrier and engage positively within an internally toothed band gear. Torque and power are distributed among a number of planet gears. Sun equipment, planet carrier and band gear may either be driving, driven or fixed. Planetary gears are used in automotive building 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 consists of two planet gear sets, each with three world gears. The ring gear of the first stage is definitely coupled to the planet carrier of the second stage. By fixing individual gears, you’ll be able to configure a complete of four different transmission ratios. The gear is accelerated with a cable drum and a variable group of weights. The set of weights is elevated via a crank. A ratchet helps prevent the weight from accidentally escaping. A clamping roller freewheel enables free further rotation after the weight has been released. The weight is definitely caught by a shock absorber. A transparent protective cover helps prevent accidental contact with the rotating parts.
In order to determine the effective torques, the power measurement measures the deflection of bending beams. Inductive acceleration sensors on all drive gears permit the speeds to be measured. The measured values are transmitted right to a Personal computer via USB. The info 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 adjustable set of weights
weight raised yourself 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
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 phase; 120V, 60Hz, 1 phase
UL/CSA optional
he most basic form of planetary gearing involves three sets of gears with different degrees of freedom. World gears rotate around axes that revolve around a sun gear, which spins set up. A ring equipment binds the multi stage planetary gearbox planets on the outside and is completely fixed. The concentricity of the earth grouping with the sun and ring gears means that the torque carries through a straight range. Many power trains are “comfortable” lined up straight, and the absence of offset shafts not only decreases space, it eliminates the necessity to redirect the energy or relocate other components.
In a straightforward planetary setup, input power turns sunlight gear at high acceleration. The planets, spaced around the central axis of rotation, mesh with the sun along with the fixed ring equipment, so they are forced to orbit as they roll. All the planets are installed to a single rotating member, known as a cage, arm, or carrier. As the earth carrier turns, it provides low-speed, high-torque output.
A set component isn’t at all times essential, though. In differential systems every member rotates. Planetary arrangements like this accommodate a single output driven by two inputs, or an individual input generating two outputs. For example, the differential that drives the axle within an automobile can be planetary bevel gearing – the wheel speeds represent two outputs, which must differ to handle corners. Bevel equipment 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 continuous insight of zero angular velocity.
Designers can proceed deeper with this “planetary” theme. Compound (instead of basic) planetary trains have at least two planet gears attached in collection to the same shaft, rotating and orbiting at the same quickness while meshing with different gears. Compounded planets can possess different tooth numbers, as can the gears they mesh with. Having this kind of options significantly 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 swiftness, while the reduction problems from sunlight shaft, if the developer prefers this. One more thing about substance planetary systems: the planets can mesh with (and revolve around) both fixed and rotating exterior gears simultaneously, therefore a ring gear is not essential.
Planet gears, for their size, engage a whole lot of teeth as they circle the sun gear – therefore they can simply accommodate numerous turns of the driver for every output shaft revolution. To perform a comparable decrease between a typical 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. Substance planetary systems, which are far more elaborate than the simple versions, can provide reductions many times higher. There are obvious ways to additional reduce (or as the case may be, increase) rate, such as for example connecting planetary phases in series. The rotational output of the first stage is from the input of the next, and the multiple of the individual ratios represents the final reduction.
Another option is to introduce regular gear reducers right into a planetary teach. For example, the high-quickness power might go through a typical fixedaxis pinion-and-gear set prior to the planetary reducer. Such a configuration, known as a hybrid, may also be favored as a simplistic option to additional planetary levels, or to lower insight speeds that are too high for a few planetary units to handle. It also provides an offset between your input and result. If a right angle is necessary, bevel or hypoid gears are occasionally attached to an inline planetary system. Worm and planetary combinations are uncommon since the worm reducer alone delivers such high changes in speed.