With single spur gears, a set of gears forms a gear stage. In the event that you connect several gear pairs one after another, this is known as a multi-stage gearbox. For each gear stage, the direction of rotation between the drive shaft and the output shaft is usually reversed. The entire multiplication factor 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 is a ratio to slower or a ratio to fast. In the majority of applications ratio to slower is required, since the drive torque can be multiplied by the entire multiplication element, unlike the drive speed.
A multi-stage spur gear can be realized in a technically meaningful way up to a gear ratio of approximately 10:1. The reason behind this lies in the ratio of the number of tooth. From a ratio of 10:1 the traveling gearwheel is extremely little. This has a negative effect 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 can be achieved by simply increasing the space 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 average person ratios of 5:1 and 4:1, for example. Instead of the drive shaft the planetary carrier contains the sun gear, which drives the following planet stage. A three-stage gearbox is obtained by means of increasing the space of the ring gear and adding another planet stage. A tranny 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 choices for multi-stage planetary gearboxes. The transmittable torque could be increased using additional planetary gears when doing this. The path of rotation of the drive shaft and the output shaft is usually the same, provided that the ring equipment or housing is fixed.
As the number of gear stages increases, the efficiency of the overall gearbox is decreased. With a ratio of 100:1 the performance is leaner than with a ratio of 20:1. To be able to counteract this circumstance, the actual fact that the power lack of the drive stage is usually low should be taken into concern when using multi-stage gearboxes. This is attained by reducing gearbox seal friction loss or having a drive stage that’s geometrically smaller, for instance. This also decreases the mass inertia, which is certainly advantageous in powerful applications. Single-stage planetary gearboxes are the most efficient.
Multi-stage gearboxes can also be realized by combining different types of teeth. With the right position gearbox a bevel gear and a planetary gearbox are simply combined. Here too the entire multiplication factor may be the product of the average person ratios. Depending on the kind 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 variety of ratios
Constant concentricity with planetary gears
Compact style with high transmission ratios
Combination of different gearbox types possible
Wide range 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 typical feature. With the upsurge in design intricacies of planetary gearbox, mathematical modelling is becoming 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 levels of freedom (DOF) high-acceleration planetary gearbox offers been provided in this paper, which derives a competent gear shifting system through designing the tranny schematic of eight rate gearboxes compounded with four planetary gear sets. Furthermore, with the aid of lever analogy, the transmission power circulation and relative power effectiveness have been decided to analyse the gearbox style. A simulation-based screening and validation have been performed which display the proposed model can be effective and produces satisfactory shift quality through better torque features while shifting the gears. A fresh heuristic method to determine appropriate compounding arrangement, based 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 advantages of high power density and large reduction in a little volume [1]. The vibration and noise complications of multi-stage planetary gears are usually 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 recognized using lumped-parameter models, but they didn’t provide general conclusions. Lin and Parker [6-7] formally discovered and proved the vibration framework of planetary gears with equivalent/unequal world spacing. They analytically categorized all planetary gears settings into exactly three classes, rotational, translational, and planet modes. 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 band gear [9], helical planetary gears [10], herringbone planetary gears [11], and high acceleration gears with gyroscopic effects [12].
The natural frequencies and vibration settings of multi-stage planetary gears also have received attention. Kahraman [13] established a family group 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 levels of freedom, which allows thousands of kinematic combinations. They mathematically proved that the modal characteristics of compound planetary gears had been analogous to a straightforward, single-stage planetary gear program. Meanwhile, there are various researchers concentrating on the nonlinear dynamic characteristics of the multi-stage planetary gears for engineering applications, such as for example TBM [15] and wind mill [16].
Based on the aforementioned models and vibration structure of planetary gears, many experts worried the sensitivity of the natural frequencies and vibration modes to system parameters. They investigated the effect of modal parameters such as for example tooth mesh stiffness, planet 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 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 established the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary gear eigenvalues. They used the structured vibration modes to show that eigenvalue loci of different setting types at all times cross and the ones of the same setting type veer as a model parameter is certainly varied.
However, many of the current studies only referenced the method used for single-stage planetary gears to analyze the modal features of multi-stage planetary gears, as the differences between both of these types of planetary gears were ignored. Because of the multiple degrees of freedom in multi-stage planetary gears, more detailed division of natural frequencies are required to analyze the influence of different system parameters. The aim of this paper is usually 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 used to simplify the analytical investigation of equipment vibration while keeping the main dynamic behavior produced by tooth mesh forces. In this paper, sensitivity of organic frequencies and vibration modes 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 metal, 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 linking with couplings, input shafts, output shafts
The planetary equipment is a special type of gear drive, in which the multiple planet gears revolve around a centrally arranged sunlight gear. The earth 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 equipment may either be driving, driven or fixed. Planetary gears are used in automotive construction and shipbuilding, as well as for stationary use 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 models, each with three planet gears. The ring gear of the 1st stage is usually coupled to the planet carrier of the second stage. By fixing person gears, it is possible to configure a complete of four different transmitting ratios. The gear is accelerated via a cable drum and a adjustable set of weights. The set of weights is raised with a crank. A ratchet prevents the weight from accidentally escaping. A clamping roller freewheel enables free further rotation after the weight has been released. The weight is definitely captured by a shock absorber. A transparent protective cover stops accidental connection with the rotating parts.
In order to determine the effective torques, the push measurement measures the deflection of bending beams. Inductive quickness sensors on all drive gears allow the speeds to become measured. The measured values are transmitted directly to a PC via USB. The info acquisition software is included. The angular acceleration could be read from the diagrams. Effective mass occasions of inertia are dependant on the angular acceleration.
investigation of the powerful behaviour of a 2-stage planetary gear
three world gears per stage
four different transmission ratios possible
gear 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 following the weight has been released
shock absorber for weight
transparent protective cover
force measurement on different gear stages via 3 bending pubs, display via dial gauges
inductive speed sensors
GUNT software program for data acquisition via USB below Windows 7, 8.1, 10
Technical data
2-stage planetary gear
module: 2mm
sunlight gears: multi stage planetary gearbox 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 type 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 gear 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 bears through a straight range. Many power trains are “comfortable” lined up straight, and the lack of offset shafts not only decreases space, it eliminates the necessity to redirect the energy or relocate other parts.
In a straightforward planetary setup, input power turns sunlight gear at high rate. The planets, spaced around the central axis of rotation, mesh with sunlight and also the fixed ring equipment, so they are pressured to orbit as 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 usually essential, though. In differential systems every member rotates. Planetary arrangements like this accommodate a single result powered by two inputs, or an individual input traveling two outputs. For instance, 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 gear planetary systems operate along the same principle as parallel-shaft systems.
Even a simple planetary gear train offers two inputs; an anchored band gear represents a constant input of zero angular velocity.
Designers can go deeper with this “planetary” theme. Compound (instead of simple) planetary trains possess at least two planet 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 figures, as can the gears they mesh with. Having such options significantly expands the mechanical opportunities, and allows more decrease per stage. Substance planetary trains can certainly be configured therefore the world carrier shaft drives at high acceleration, while the reduction issues from the sun 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 exterior gears simultaneously, hence a ring gear isn’t essential.
Planet gears, for his or her size, engage a lot of teeth because they circle the sun equipment – therefore they can easily accommodate many turns of the driver for every output shaft revolution. To perform a comparable decrease between a typical pinion and equipment, a sizable gear will need to mesh with a fairly small pinion.
Simple planetary gears generally offer reductions as high as 10:1. Substance planetary systems, which are more elaborate compared to the simple versions, can offer reductions often higher. There are obvious ways to additional decrease (or as the case could be, increase) speed, such as connecting planetary phases in series. The rotational result of the 1st stage is linked to the input of the next, and the multiple of the individual ratios represents the ultimate reduction.
Another option is to introduce standard gear reducers into a planetary train. For example, 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 alternative to additional planetary stages, or to lower input speeds that are too high for some planetary units to take care of. It also has an offset between your input and result. If the right angle is necessary, bevel or hypoid gears are sometimes attached to an inline planetary system. Worm and planetary combinations are rare since the worm reducer alone delivers such high adjustments in speed.