With single spur gears, a pair of gears forms a gear stage. In the event that you connect several gear pairs one after another, this is referred to as a multi-stage gearbox. For each gear stage, the path of rotation between your drive shaft and the output shaft is certainly reversed. The overall multiplication element 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’s a ratio to slow or a ratio to fast. In the majority of applications ratio to sluggish is required, since the drive torque can be multiplied by the entire multiplication aspect, unlike the drive quickness.
A multi-stage spur gear can be realized in a technically meaningful way up to gear ratio of around 10:1. The reason for this is based on the ratio of the amount of the teeth. 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 becoming 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 merely increasing the length of the ring equipment and with serial arrangement of many 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. Rather than the drive shaft the planetary carrier contains the sun gear, which drives the following world stage. A three-stage gearbox is usually obtained through increasing the space of the ring equipment 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 person ratios can be combined, which outcomes in a big number of ratio options for multi-stage planetary gearboxes. The transmittable torque can be increased using additional planetary gears when doing this. The path of rotation of the drive shaft and the result shaft is always the same, provided that the ring gear or housing is fixed.
As the amount of equipment stages increases, the efficiency of the overall gearbox is reduced. With a ratio of 100:1 the efficiency is lower than with a ratio of 20:1. To be able to counteract this circumstance, the actual fact that the power loss of the drive stage is low must be taken into factor when using 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 are the most efficient.
Multi-stage gearboxes may also be realized by combining multi stage planetary gearbox different types of teeth. With the right position gearbox a bevel gear and a planetary gearbox are simply combined. Here as well the overall multiplication factor is the product of the average person ratios. Depending on the type of gearing and the type of bevel gear stage, the drive and the output can rotate in the same path.
Benefits of multi-stage gearboxes:
Wide range 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 amount of efficiency
The automatic 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 character and therefore there is a dependence on modelling of multistage planetary gearbox like the shifting scheme. A random search-centered synthesis of three levels of freedom (DOF) high-speed planetary gearbox has been shown in this paper, which derives a competent gear shifting system through designing the transmission schematic of eight quickness gearboxes compounded with four planetary gear sets. Furthermore, with the aid of lever analogy, the tranny power circulation and relative power performance have been determined to analyse the gearbox style. A simulation-based tests and validation have been performed which show the proposed model is usually efficient and produces satisfactory shift quality through better torque features while shifting the gears. A new heuristic solution to determine suitable compounding arrangement, predicated on mechanism enumeration, for designing a gearbox layout is proposed here.
Multi-stage planetary gears are widely used in many applications such as automobiles, helicopters and tunneling uninteresting machine (TBM) due to their benefits of high power density and huge reduction in a small volume [1]. The vibration and noise complications of multi-stage planetary gears are constantly 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 framework of some example planetary gears are recognized using lumped-parameter models, but they didn’t give general conclusions. Lin and Parker [6-7] formally discovered and proved the vibration structure of planetary gears with equivalent/unequal planet spacing. They analytically classified all planetary gears modes 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 were carried into systems modeled with an elastic continuum band equipment [9], helical planetary gears [10], herringbone planetary gears [11], and high quickness gears with gyroscopic effects [12].
The organic frequencies and vibration settings of multi-stage planetary gears also have received attention. Kahraman [13] established a family of torsional dynamics models for substance planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic style of compound planetary gears of general description including translational degrees of freedom, which enables an infinite number of kinematic combinations. They mathematically proved that the modal characteristics of substance planetary gears were analogous to a simple, single-stage planetary gear program. Meanwhile, there are several researchers concentrating on the nonlinear dynamic features of the multi-stage planetary gears for engineering applications, such as for example TBM [15] and wind mill [16].
According to the aforementioned models and vibration structure 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 gear natural 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-type expressions for the eigensensitivities to model parameter variations according to the well-defined vibration setting properties, and founded the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary gear eigenvalues. They utilized the structured vibration modes to show that eigenvalue loci of different setting types usually cross and the ones of the same mode type veer as a model parameter is definitely varied.
However, many of the current studies just referenced the technique used for single-stage planetary gears to investigate the modal features of multi-stage planetary gears, while the differences between both of these types of planetary gears were ignored. Because of the multiple levels of freedom in multi-stage planetary gears, more detailed division of organic frequencies must analyze the influence of different program parameters. The objective of this paper can be to propose an innovative way of analyzing the coupled modes in multi-stage planetary gears to investigate the parameter sensitivities. Purely rotational degree of freedom models are used to simplify the analytical investigation of gear vibration while keeping the main dynamic behavior produced by tooth mesh forces. In this paper, sensitivity of organic frequencies and vibration settings to both equipment 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, 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 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 sun gear. The planet gears are installed on a world carrier and engage positively in an internally toothed band equipment. Torque and power are distributed among several planet gears. Sun gear, planet carrier and band gear may either be traveling, driven or set. Planetary gears are used in automotive construction 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 contains two planet gear units, each with three world gears. The ring gear of the initial stage is coupled to the earth 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 via a cable drum and a adjustable group 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 following the weight offers been released. The weight is definitely caught by a shock absorber. A transparent protective cover prevents accidental connection with the rotating parts.
In order to determine the effective torques, the push measurement measures the deflection of bending beams. Inductive speed sensors on all drive gears allow the speeds to be measured. The measured ideals are transmitted directly to a 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
gear is accelerated via cable drum and adjustable set of weights
weight raised by hand crank; ratchet prevents accidental release
clamping roller freewheel allows free further rotation following the weight has been released
shock absorber for weight
transparent protective cover
push measurement on different gear levels 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
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 stage; 120V, 60Hz, 1 phase
UL/CSA optional
he most basic kind of planetary gearing involves three sets of gears with different examples 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 set. The concentricity of the planet grouping with the sun and ring gears means that the torque carries through a straight series. 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 parts.
In a straightforward planetary setup, input power turns the sun gear at high velocity. The planets, spaced around the central axis of rotation, mesh with sunlight along with the fixed ring equipment, so they are forced to orbit because they roll. All the planets are installed to a single 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 constantly essential, though. In differential systems every member rotates. Planetary arrangements like this accommodate a single output driven by two inputs, or a single input driving two outputs. For instance, 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 gear planetary systems operate along the same principle as parallel-shaft systems.
Even a simple planetary gear train has two inputs; an anchored band gear represents a constant insight of zero angular velocity.
Designers can proceed deeper with this “planetary” theme. Compound (as opposed to simple) planetary trains possess at least two planet gears attached in collection to the same shaft, rotating and orbiting at the same acceleration while meshing with different gears. Compounded planets can have got different tooth figures, as can the gears they mesh with. Having such options greatly expands the mechanical opportunities, and allows more reduction per stage. Substance planetary trains can easily be configured so the planet 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 fixed and rotating exterior gears simultaneously, therefore a ring gear isn’t essential.
Planet gears, for his or her size, engage a whole lot of teeth because they circle the sun equipment – therefore they can easily accommodate numerous turns of the driver for each result shaft revolution. To execute a comparable reduction between a standard pinion and gear, a sizable gear will have to mesh with a rather small pinion.
Simple planetary gears generally provide reductions as high as 10:1. Compound planetary systems, which are far more elaborate compared to the simple versions, can provide reductions often higher. There are apparent ways to additional decrease (or as the case may be, increase) velocity, such as 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 standard gear reducers into a planetary teach. For example, the high-acceleration power might go through a typical fixedaxis pinion-and-gear set prior to the planetary reducer. This kind of a configuration, called a hybrid, is sometimes favored as a simplistic alternative to additional planetary stages, or to lower insight 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 necessary, bevel or hypoid gears are sometimes mounted on an inline planetary program. Worm 
and planetary combinations are uncommon since the worm reducer by itself delivers such high adjustments in speed.
