With single spur gears, a couple 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 output shaft can be reversed. The overall multiplication element 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’s a ratio to slow or a ratio to fast. In the majority of applications ratio to slower is required, because the drive torque is certainly multiplied by the overall multiplication aspect, unlike the drive rate.
A multi-stage spur gear could be realized in a technically meaningful way up to gear ratio of approximately 10:1. The reason for this lies in the ratio of the amount of tooth. From a ratio of 10:1 the generating gearwheel is extremely little. This has a poor influence 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 merely increasing the distance of the ring equipment and with serial arrangement of a number of individual planet stages. A planetary equipment with a ratio of 20:1 could be manufactured from the average person ratios of 5:1 and 4:1, for instance. 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 way of increasing the space of the ring gear and adding another planet stage. A tranny ratio of 100:1 is obtained using person ratios of 5:1, 5:1 and 4:1. Basically, all individual ratios can be combined, which outcomes in a big number of ratio choices for multi-stage planetary gearboxes. The transmittable torque can be increased using extra planetary gears when performing this. The direction of rotation of the drive shaft and the result shaft is often the same, provided that the ring equipment or casing is fixed.
As the number of equipment stages increases, the efficiency of the entire gearbox is decreased. With a ratio of 100:1 the effectiveness is lower than with a ratio of 20:1. In order to counteract this circumstance, the fact that the power loss of the drive stage can be low must be taken into account when using multi-stage gearboxes. That is attained by reducing gearbox seal friction reduction or having a drive stage that’s geometrically smaller, for example. This also decreases the mass inertia, which can be 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 too the overall multiplication factor is the product of the average person ratios. Depending on the type of gearing and the kind of bevel gear stage, the drive and the result can rotate in the same path.
Advantages of multi-stage gearboxes:
Wide variety of ratios
Continuous concentricity with planetary gears
Compact style with high transmission ratios
Mix of different gearbox types possible
Wide variety of uses
Disadvantages of multi-stage gearboxes (in comparison to single-stage gearboxes):
More complex design
Lower amount of efficiency
The automated transmission system is very crucial for the high-speed vehicles, where in fact the planetary or epicyclic gearbox is a standard feature. With the upsurge in design intricacies of planetary gearbox, mathematical modelling is becoming complex in character and for that reason there is a dependence on modelling of multistage planetary gearbox including the shifting scheme. A random search-centered synthesis of three examples of freedom (DOF) high-speed planetary gearbox provides been shown in this paper, which derives an efficient gear shifting system through designing the transmitting schematic of eight speed gearboxes compounded with four planetary gear sets. Furthermore, by making use of lever analogy, the transmitting power movement and relative power effectiveness have been motivated to analyse the gearbox design. A simulation-based tests and validation have already been performed which show the proposed model is certainly effective and produces satisfactory change quality through better torque characteristics while shifting the gears. A fresh heuristic solution to determine ideal compounding arrangement, based 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) due to their benefits of high power density and huge reduction in a little volume [1]. The vibration and noise problems of multi-stage planetary gears are often 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 structure of some example planetary gears are determined using lumped-parameter models, however they didn’t give general conclusions. Lin and Parker [6-7] formally determined and proved the vibration framework of planetary gears with the same/unequal world spacing. They analytically classified all planetary gears modes into exactly three categories, rotational, translational, and planet settings. Parker [8] also investigated the clustering phenomenon of the three setting types. In the latest literatures, the systematic classification of settings had been carried into systems modeled with an elastic continuum band gear [9], helical planetary gears [10], herringbone planetary gears [11], and high speed gears with gyroscopic effects [12].
The natural frequencies and vibration settings of multi-stage planetary gears also have received attention. Kahraman [13] founded a family of torsional multi stage planetary gearbox dynamics versions for compound 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 enables thousands of kinematic combinations. They mathematically proved that the modal characteristics of substance planetary gears had been analogous to a simple, single-stage planetary gear program. Meanwhile, there are various researchers focusing on the nonlinear dynamic features of the multi-stage planetary gears for engineering applications, such as TBM [15] and wind mill [16].
Based on the aforementioned models and vibration framework of planetary gears, many researchers concerned the sensitivity of the natural frequencies and vibration modes 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 modes [17-19]. Parker et al. [20-21] mathematically analyzed the effects of style parameters on natural frequencies and vibration settings both for the single-stage and compound planetary gears. They proposed closed-type expressions for the eigensensitivities to model parameter variants 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 equipment eigenvalues. They utilized the organized vibration modes to show that eigenvalue loci of different mode types constantly cross and those of the same setting type veer as a model parameter is certainly varied.
However, most of the current studies just referenced the method used for single-stage planetary gears to analyze the modal characteristics 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 influence of different program parameters. The objective of this paper is usually to propose an innovative way of examining 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 equipment vibration while keeping the primary dynamic behavior produced 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 can be found in wide reduction gear ratios
2. Gear set 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 established torque range: Low torque, middle torque, high torque
6. Easy connecting with couplings, input shafts, result shafts
The planetary equipment is a special kind of gear drive, where 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 equipment, planet carrier and band equipment may either be traveling, driven or fixed. Planetary gears are used in automotive structure 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 includes two planet gear models, each with three planet gears. The ring gear of the 1st stage is certainly coupled to the planet carrier of the second stage. By fixing person gears, it is possible to configure a complete of four different tranny ratios. The apparatus is accelerated via a cable drum and a variable group of weights. The group of weights is raised with a crank. A ratchet helps prevent the weight from accidentally escaping. A clamping roller freewheel enables free further rotation following the weight provides been released. The weight is definitely captured by a shock absorber. A transparent protective cover prevents accidental contact with the rotating parts.
In order to determine the effective torques, the force measurement measures the deflection of bending beams. Inductive velocity sensors on all drive gears permit the speeds to be measured. The measured ideals are transmitted directly to a Personal computer via USB. The info acquisition software is roofed. The angular acceleration could be read from the diagrams. Effective mass moments of inertia are dependant on 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 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
sun 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 type of planetary gearing involves three sets of gears with different examples of freedom. Planet gears rotate around axes that revolve around a sunlight gear, which spins set up. A ring equipment binds the planets externally and is completely set. The concentricity of the earth grouping with the sun and ring gears implies that the torque carries through a straight range. Many power trains are “comfortable” lined up straight, and the lack of offset shafts not merely reduces space, it eliminates the necessity 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 sunlight as well as the fixed ring equipment, so they are pressured to orbit as they roll. All the planets are installed to an individual rotating member, known as a cage, arm, or carrier. As the planet carrier turns, it provides low-speed, high-torque output.
A fixed component isn’t often essential, though. In differential systems every member rotates. Planetary arrangements such as this accommodate a single output powered by two inputs, or an individual input traveling two outputs. For example, the differential that drives the axle within an vehicle can be planetary bevel gearing – the wheel speeds represent two outputs, which must differ to handle corners. Bevel gear planetary systems operate along the same theory as parallel-shaft systems.
A good 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 (instead of simple) planetary trains have at least two world gears attached in series to the same shaft, rotating and orbiting at the same swiftness while meshing with different gears. Compounded planets can have different tooth amounts, as can the gears they mesh with. Having this kind of options greatly expands the mechanical opportunities, and allows more decrease per stage. Compound planetary trains can certainly be configured so the planet carrier shaft drives at high speed, while the reduction issues from sunlight shaft, if the developer prefers this. One more thing about substance planetary systems: the planets can mesh with (and revolve around) both set and rotating exterior gears simultaneously, hence a ring gear is not essential.
Planet gears, for their size, engage a lot of teeth because they circle the sun equipment – therefore they can simply accommodate several turns of the driver for every output shaft revolution. To perform a comparable decrease between a standard pinion and gear, a sizable gear will have to mesh with a fairly small pinion.
Simple planetary gears generally provide reductions as high as 10:1. Substance planetary systems, which are far more elaborate compared to the simple versions, can offer reductions many times higher. There are apparent ways to further decrease (or as the case could be, increase) rate, such as for example connecting planetary stages in series. The rotational output of the 1st stage is linked to 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 train. For instance, the high-swiftness power might pass through a typical fixedaxis pinion-and-gear set before the planetary reducer. This kind of a configuration, known as a hybrid, may also be preferred as a simplistic option to additional planetary levels, or to lower insight speeds that are too much for some planetary units to handle. It also provides an offset between the input and result. If the right angle is needed, bevel or hypoid gears are sometimes mounted on an inline planetary system. Worm and planetary combinations are rare because the worm reducer by itself delivers such high changes in speed.