With single spur gears, a pair of gears forms a gear stage. If you connect several equipment pairs one after another, that is referred to as a multi-stage gearbox. For each gear stage, the direction of rotation between your drive shaft and the result shaft is usually reversed. The entire multiplication aspect 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 gear ratio, depending on whether it’s a ratio to slower or a ratio to fast. In nearly all applications ratio to slower is required, since the drive torque is usually multiplied by the overall multiplication aspect, unlike the drive velocity.
A multi-stage spur gear can be realized in a technically meaningful method up to 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 small. This has a poor influence on the tooth geometry and the torque that is becoming transmitted. With planetary gears a multi-stage gearbox is incredibly easy to realize.
A two-stage gearbox or a three-stage gearbox may be accomplished by just increasing the space of the ring gear and with serial arrangement of several individual planet levels. A planetary equipment with a ratio of 20:1 can be manufactured from the average person ratios of 5:1 and 4:1, for example. Rather than the drive shaft the planetary carrier contains the sun gear, which drives the next planet stage. A three-stage gearbox can be obtained by way of increasing the distance of the ring equipment and adding another world stage. A transmitting 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 big number of ratio choices for multi-stage planetary gearboxes. The transmittable torque could be increased using extra planetary gears when doing this. The path of rotation of the drive shaft and the output shaft is always the same, provided that the ring equipment 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 effectiveness is leaner than with a ratio of 20:1. To be able to counteract this circumstance, the fact that the power lack of the drive stage can be low must be taken into thought when working with 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 is 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 the right position gearbox a bevel equipment and a planetary gearbox are simply combined. Here as well the entire 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 result can rotate in the same direction.
Benefits of multi-stage gearboxes:
Wide range of ratios
Constant 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 increase in design intricacies of planetary gearbox, mathematical modelling has become complex in character and for that reason there is a need for modelling of multistage planetary gearbox including the shifting scheme. A random search-based synthesis of three levels of freedom (DOF) high-acceleration planetary gearbox has been offered in this paper, which derives an efficient gear shifting mechanism through designing the tranny schematic of eight acceleration gearboxes compounded with four planetary gear sets. Furthermore, with the help of lever analogy, the transmitting power stream and relative power performance have been determined to analyse the gearbox style. A simulation-based assessment and validation have already been performed which show the proposed model is certainly effective and produces satisfactory change quality through better torque features 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 large reduction in a small volume [1]. The vibration and noise problems of multi-stage planetary gears are generally 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 determined using lumped-parameter models, however they didn’t provide general conclusions. Lin and Parker [6-7] formally discovered and proved the vibration framework of planetary gears with equivalent/unequal planet spacing. They analytically classified all planetary gears modes into exactly three types, 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 settings had been 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] set up a family group of torsional dynamics models for substance planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic model of compound planetary gears of general explanation including translational levels of freedom, which enables an infinite number of kinematic combinations. They mathematically proved that the modal characteristics of compound planetary gears were analogous to a simple, single-stage planetary gear system. Meanwhile, there are plenty of researchers focusing 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 worried the sensitivity of the organic frequencies and vibration settings to system parameters. They investigated the effect of modal parameters such as tooth mesh stiffness, world bearing stiffness and support stiffness on planetary gear natural frequencies and vibration modes [17-19]. Parker et al. [20-21] mathematically analyzed the consequences of design 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 variants based on the well-defined vibration mode properties, and set up the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary gear eigenvalues. They used the structured vibration modes showing that eigenvalue loci of different mode types usually cross and those of the same setting 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 these two types of planetary gears had been ignored. Due to the multiple levels of freedom in multi-stage planetary gears, more detailed division of natural frequencies must analyze the impact of different system parameters. The aim of this paper is certainly to propose a novel method of examining the coupled modes in multi-stage planetary gears to investigate the parameter sensitivities. Purely rotational amount of freedom models are accustomed to simplify the analytical investigation of equipment 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 arranged can combine the same or different ratios
3. Planetary gear set comes in plastic, sintered metallic, and steel, depending on different application
4. Hight efficiency: 98% efficiency at single decrease, 95% at double reduction
5. Planetary gear set torque range: Low torque, middle torque, high torque
6. Easy connecting with couplings, input shafts, result shafts
The planetary gear is a special kind of gear drive, where the multiple planet gears revolve around a centrally arranged sunlight gear. The earth gears are installed on a planet carrier and engage positively within an internally toothed ring gear. Torque and power are distributed among many planet gears. Sun equipment, planet carrier and ring equipment may either be driving, driven or set. Planetary gears are used in automotive building and shipbuilding, aswell as for stationary use 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 pieces, each with three world gears. The ring equipment of the initial stage is certainly coupled to the earth carrier of the next stage. By fixing individual gears, it is possible to configure a complete of four different transmitting ratios. The apparatus is accelerated via a cable drum and a adjustable set of weights. The set of weights is raised with a crank. A ratchet stops the weight from accidentally escaping. A clamping roller freewheel enables free further rotation after the weight has been released. The weight can be captured by a shock absorber. A transparent protective cover helps prevent accidental connection with the rotating parts.
In order to determine the effective torques, the push measurement measures the deflection of bending beams. Inductive acceleration sensors on all drive gears permit the speeds to be measured. The measured ideals are transmitted right to a Computer via USB. The info acquisition software is roofed. The multi stage planetary gearbox angular acceleration could be read from the diagrams. Effective mass moments 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 allows free further rotation following the weight has been released
shock absorber for weight
transparent protective cover
drive measurement on different gear levels via 3 bending pubs, 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
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 examples of freedom. World 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 collection. Many power trains are “comfortable” lined up straight, and the absence of offset shafts not merely reduces space, it eliminates the 
need to redirect the power or relocate other parts.
In a straightforward 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 gear, so they are forced to orbit because they roll. All the planets are mounted to an individual rotating member, known as a cage, arm, or carrier. As the earth carrier turns, it delivers low-speed, high-torque output.
A set 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 generating 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 provides two inputs; an anchored ring gear represents a constant insight of zero angular velocity.
Designers can go deeper with this “planetary” theme. Compound (as opposed to simple) planetary trains have at least two world gears attached in range to the same shaft, rotating and orbiting at the same speed while meshing with different gears. Compounded planets can possess different tooth amounts, as can the gears they mesh with. Having this kind of options significantly expands the mechanical opportunities, and allows more decrease per stage. Substance planetary trains can easily be configured so the planet carrier shaft drives at high quickness, while the reduction issues from the sun shaft, if the developer prefers this. Another thing about substance planetary systems: the planets can mesh with (and revolve around) both set and rotating exterior gears simultaneously, therefore a ring gear isn’t essential.
Planet gears, for their size, engage a whole lot of teeth because they circle the sun equipment – therefore they can certainly accommodate many turns of the driver for each result shaft revolution. To perform a comparable reduction between a typical pinion and equipment, a sizable gear will have to mesh with a rather small pinion.
Simple planetary gears generally offer reductions as high as 10:1. Compound planetary systems, which are far more elaborate than the simple versions, can offer reductions many times 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 result of the initial stage is from the input of the next, and the multiple of the individual ratios represents the final reduction.
Another choice is to introduce standard gear reducers into a planetary train. For example, the high-speed power might pass through an ordinary fixedaxis pinion-and-gear set prior to the planetary reducer. Such a configuration, known as a hybrid, may also be preferred as a simplistic option to additional planetary stages, or to lower input speeds that are too high for a few planetary units to handle. It also provides an offset between the input and result. 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 changes in speed.
