With single spur gears, a set of gears forms a gear stage. If you connect several equipment pairs one after another, this is referred to as a multi-stage gearbox. For every gear stage, the direction of rotation between the drive shaft and the result shaft is reversed. The overall multiplication element of multi-stage gearboxes is 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 gradual or a ratio to fast. In the majority of applications ratio to sluggish is required, because the drive torque can be multiplied by the overall multiplication element, unlike the drive acceleration.
A multi-stage spur gear could be realized in a technically meaningful method up to a gear ratio of around 10:1. The reason for this is based on the ratio of the number of teeth. From a ratio of 10:1 the generating gearwheel is extremely little. This has a negative influence on the tooth geometry and the torque that’s being 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 simply 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 instance. Instead of the drive shaft the planetary carrier provides the sun gear, which drives the next world stage. A three-stage gearbox is certainly obtained by means of increasing the distance of the ring gear 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 outcomes in a large number of ratio options for multi-stage planetary gearboxes. The transmittable torque can be increased using additional planetary gears when carrying out this. The path of rotation of the drive shaft and the output shaft is constantly the same, provided that the ring gear or casing is fixed.
As the amount of gear stages increases, the efficiency of the overall 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 circumstance, the actual fact that the power loss of the drive stage is usually low should be taken into factor when using multi-stage gearboxes. That is achieved by reducing gearbox seal friction reduction or having a drive stage that is geometrically smaller, for instance. This also decreases the mass inertia, which is definitely 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 the right angle gearbox a bevel gear and a planetary gearbox are simply combined. Here too 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 result can rotate in the same direction.
Benefits of multi-stage gearboxes:
Wide range of ratios
Continuous 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 (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 in fact the planetary or epicyclic gearbox is a typical feature. With the upsurge in style intricacies of planetary gearbox, mathematical modelling has become 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 levels of freedom (DOF) high-rate planetary gearbox provides been offered in this paper, which derives an efficient gear shifting system through designing the transmission schematic of eight swiftness gearboxes compounded with four planetary gear sets. Furthermore, by using lever analogy, the tranny power circulation and relative power effectiveness have been determined to analyse the gearbox style. A simulation-based testing and validation have already been performed which show the proposed model is certainly efficient 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 layout is proposed here.
Multi-stage planetary gears are widely used in many applications such as for example automobiles, helicopters and tunneling boring machine (TBM) due to their benefits of high power density and huge reduction in a small volume [1]. The vibration and noise problems of multi-stage planetary gears are at all times the focus of multi stage planetary gearbox 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 recognized using lumped-parameter models, however they didn’t give general conclusions. Lin and Parker [6-7] formally identified and proved the vibration structure of planetary gears with the same/unequal planet spacing. They analytically classified all planetary gears modes into exactly three classes, rotational, translational, and world settings. Parker [8] also investigated the clustering phenomenon of the three mode 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 organic frequencies and vibration modes of multi-stage planetary gears have also received attention. Kahraman [13] established a family group of torsional dynamics models for compound planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic style of compound planetary gears of general description including translational levels of freedom, which allows thousands of kinematic combinations. They mathematically proved that the modal features of substance planetary gears had been analogous to a simple, single-stage planetary gear system. Meanwhile, there are several 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 researchers concerned the sensitivity of the natural 
frequencies and vibration settings to program parameters. They investigated the result of modal parameters such as for example tooth mesh stiffness, planet 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 style parameters on natural frequencies and vibration modes both for the single-stage and substance planetary gears. They proposed closed-form expressions for the eigensensitivities to model parameter variations 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 organized vibration modes to show that eigenvalue loci of different setting types often cross and the ones of the same setting type veer as a model parameter is usually varied.
However, many of the current 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 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 natural frequencies are required to analyze the impact of different system parameters. The objective of this paper is usually to propose a novel method of examining the coupled settings 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 equipment 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 is available in plastic, sintered steel, and steel, depending on different application
4. Hight efficiency: 98% efficiency at single decrease, 95% at double reduction
5. Planetary gear arranged torque range: Low torque, middle torque, high torque
6. Easy connecting with couplings, input shafts, result shafts
The planetary equipment is a special type of gear drive, where the multiple world gears revolve around a centrally arranged sun gear. The planet gears are installed on a planet 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 generating, driven or fixed. Planetary gears are found in automotive construction and shipbuilding, aswell as for stationary make use of in turbines and general mechanical engineering.
The GL 212 unit allows the investigation of the powerful behaviour of a two-stage planetary gear. The trainer consists of two planet gear pieces, each with three planet gears. The ring gear of the first stage is usually coupled to the planet carrier of the second stage. By fixing person gears, it is possible to configure a total of four different transmission ratios. The gear is accelerated with a cable drum and a adjustable set of weights. The set of weights is raised via a crank. A ratchet helps prevent the weight from accidentally escaping. A clamping roller freewheel allows free further rotation after the weight has been released. The weight is caught by a shock absorber. A transparent protective cover stops accidental contact with the rotating parts.
In order to determine the effective torques, the drive measurement measures the deflection of bending beams. Inductive speed sensors on all drive gears allow the speeds to end up being measured. The measured ideals 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 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 allows free further rotation after the weight has been released
shock absorber for weight
transparent protective cover
push measurement on different gear stages 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
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 phase; 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 sun 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 the sun and ring gears implies that the torque bears through a straight range. Many power trains are “comfortable” prearranged straight, and the absence of offset shafts not only reduces space, it eliminates the necessity to redirect the energy or relocate other components.
In a straightforward planetary setup, input power turns the sun gear at high swiftness. 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 because they roll. All the planets are mounted to a single rotating member, called a cage, arm, or carrier. As the planet 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 such as this accommodate a single output powered by two inputs, or a single input driving two outputs. For example, the differential that drives the axle in an vehicle is usually planetary bevel gearing – the wheel speeds represent two outputs, which must differ to take care of corners. Bevel equipment planetary systems operate along the same theory as parallel-shaft systems.
Even a simple planetary gear train offers two inputs; an anchored ring gear represents a constant insight of zero angular velocity.
Designers can move deeper with this “planetary” theme. Compound (as opposed to simple) planetary trains have at least two world gears attached in collection to the same shaft, rotating and orbiting at the same quickness while meshing with different gears. Compounded planets can have different tooth figures, as can the gears they mesh with. Having this kind of options greatly expands the mechanical possibilities, and allows more reduction per stage. Substance planetary trains can simply be configured so the planet carrier shaft drives at high acceleration, while the reduction problems from sunlight shaft, if the designer 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 whole lot of teeth as they circle the sun gear – therefore they can easily accommodate many turns of the driver for each output shaft revolution. To execute a comparable reduction between a standard pinion and equipment, a sizable gear will need to mesh with a fairly small pinion.
Basic planetary gears generally provide 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 further decrease (or as the case could be, increase) swiftness, such as for example connecting planetary stages in series. The rotational output of the first stage is from the input of another, and the multiple of the average person ratios represents the ultimate reduction.
Another option is to introduce regular gear reducers right into a planetary train. For instance, the high-swiftness power might pass through an ordinary fixedaxis pinion-and-gear set prior to the planetary reducer. Such a configuration, called a hybrid, may also be preferred as a simplistic option to additional planetary phases, or to lower input speeds that are too much for some planetary units to take care of. It also has an offset between your input and result. If a right angle is necessary, bevel or hypoid gears are sometimes attached to an inline planetary program. Worm and planetary combinations are rare since the worm reducer alone delivers such high changes in speed.
