With single spur gears, a set 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 every gear stage, the direction of rotation between your drive shaft and the output shaft is certainly reversed. The entire multiplication factor of multi-stage gearboxes is definitely 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 nearly all applications ratio to sluggish is required, since the drive torque is multiplied by the entire multiplication factor, unlike the drive velocity.
A multi-stage spur gear can be realized in a technically meaningful way up to gear ratio of around 10:1. The reason behind this is based on the ratio of the amount of tooth. From a ratio of 10:1 the traveling gearwheel is extremely little. This has a negative influence on the tooth geometry and the torque that's getting 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 merely increasing the length 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 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 next world stage. A three-stage gearbox is definitely obtained by way of increasing the length of the ring gear 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 large 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 at all times the same, provided that the ring gear or housing is fixed.
As the number 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 fact that the power loss of the drive stage is low must be taken into thought when working with multi-stage gearboxes. This is achieved by reducing gearbox seal friction reduction or having a drive stage that's geometrically smaller, for instance. This also reduces the mass inertia, which can be advantageous in powerful applications. Single-stage planetary gearboxes are the most efficient.
Multi-stage gearboxes can also be realized by combining various kinds of teeth. With the right angle gearbox a bevel equipment and a planetary gearbox are simply combined. Here as well the overall multiplication factor may be the product of the individual ratios. Depending on the type of gearing and the type of bevel equipment stage, the drive and the output 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 (in comparison to single-stage gearboxes):
More complex design
Lower degree of efficiency
The automatic transmission system is quite crucial for the high-speed vehicles, where the planetary or epicyclic gearbox is a typical feature. With the increase in style intricacies of planetary gearbox, mathematical modelling has become complex in nature and therefore there is a need for modelling of multistage planetary gearbox like the shifting scheme. A random search-based synthesis of three degrees of freedom (DOF) high-acceleration planetary gearbox has been shown in this paper, which derives a competent gear shifting system through designing the transmitting schematic of eight speed gearboxes compounded with four planetary gear sets. Furthermore, with the aid of lever analogy, the tranny power movement and relative power efficiency have been motivated to analyse the gearbox design. A simulation-based assessment and validation have been performed which show the proposed model is certainly effective and produces satisfactory change quality through better torque characteristics while shifting the gears. A new heuristic method to determine suitable compounding arrangement, based on mechanism enumeration, for designing a gearbox design is proposed here.
Multi-stage planetary gears are widely used in many applications such as for example automobiles, helicopters and tunneling boring machine (TBM) because of their advantages of high power density and large reduction in a small 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 identified 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 equivalent/unequal planet spacing. They analytically classified all planetary gears modes into exactly three types, rotational, translational, and planet settings. Parker [8] also investigated the clustering phenomenon of the three mode types. In the recent literatures, the systematic classification of settings were carried into systems modeled with an elastic continuum ring gear [9], helical planetary gears [10], herringbone planetary gears [11], and high acceleration gears with gyroscopic effects [12].
The natural frequencies and vibration modes of multi-stage planetary gears also have received attention. Kahraman [13] founded a family group of torsional dynamics models for substance planetary gears under different kinematic multi stage planetary gearbox configurations. Kiracofe [14] developed a dynamic style of substance planetary gears of general description including translational degrees of freedom, which allows thousands of kinematic combinations. They mathematically proved that the modal features of compound planetary gears were analogous to a simple, single-stage planetary gear program. Meanwhile, there are many researchers focusing on the nonlinear dynamic features of the multi-stage planetary gears for engineering applications, such as TBM [15] and wind turbine [16].
Based on the aforementioned models and vibration framework of planetary gears, many experts worried the sensitivity of the organic 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 organic frequencies and vibration settings [17-19]. Parker et al. [20-21] mathematically analyzed the consequences of design parameters on organic frequencies and vibration modes both for the single-stage and compound planetary gears. They proposed closed-type expressions for the eigensensitivities to model parameter variations based on the well-defined vibration setting properties, and founded the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary equipment eigenvalues. They utilized the structured vibration modes to show that eigenvalue loci of different setting types constantly cross and those of the same setting type veer as a model parameter is varied.
However, most of the existing studies only referenced the technique used for single-stage planetary gears to analyze the modal characteristics of multi-stage planetary gears, as 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 descriptive division of natural frequencies must analyze the influence of different program parameters. The aim of this paper is to propose a novel method of examining the coupled modes in multi-stage planetary gears to investigate the parameter sensitivities. Purely rotational degree of freedom models are accustomed to simplify the analytical investigation of gear vibration while keeping the main dynamic behavior generated 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 comes in plastic, sintered steel, and steel, based on different application
4. Hight efficiency: 98% efficiency at single decrease, 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 type of gear drive, where the multiple world gears revolve around a centrally arranged sunlight gear. The earth gears are installed on a world carrier and engage positively in an internally toothed band gear. Torque and power are distributed among several planet gears. Sun equipment, planet carrier and band gear may either be generating, driven or set. Planetary gears are used 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 dynamic behaviour of a two-stage planetary gear. The trainer includes two planet gear sets, each with three planet gears. The ring gear of the initial stage is usually coupled to the earth carrier of the second stage. By fixing person 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 group of weights is raised via a crank. A ratchet prevents the weight from accidentally escaping. A clamping roller freewheel enables free further rotation following the weight has been released. The weight is usually caught by a shock absorber. A transparent protective cover helps prevent accidental connection with the rotating parts.
In order to determine the effective torques, the pressure measurement measures the deflection of bending beams. Inductive rate sensors on all drive gears allow the speeds to be measured. The measured ideals are transmitted right to a Personal computer via USB. The data acquisition software is roofed. The angular acceleration could be read from the diagrams. Effective mass occasions of inertia are determined by 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 yourself 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
drive measurement on different gear levels via 3 bending bars, 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
sun gears: 24-tooth, d-pitch circle: 48mm
planet gears: 24-tooth, d-pitch circle: 48mm
band 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 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 externally and is completely fixed. The concentricity of the planet grouping with sunlight and ring gears means that the torque bears through a straight line. Many power trains are “comfortable” prearranged straight, and the absence of offset shafts not only decreases space, it eliminates the need to redirect the energy or relocate other components.
In a simple planetary setup, input power turns sunlight 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 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 generally essential, though. In differential systems every member rotates. Planetary arrangements like this accommodate a single output powered by two inputs, or an individual input generating two outputs. For example, the differential that drives the axle in an automobile is usually planetary bevel gearing – the wheel speeds represent two outputs, which must differ to handle corners. Bevel gear planetary systems operate along the same basic principle as parallel-shaft systems.
Even a simple planetary gear train offers two inputs; an anchored ring gear represents a continuous input of zero angular velocity.
Designers can go deeper with this “planetary” theme. Compound (as opposed to simple) planetary trains possess at least two planet gears attached in series to the same shaft, rotating and orbiting 
at the same rate while meshing with different gears. Compounded planets can possess different tooth numbers, 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 quickness, while the reduction issues from sunlight shaft, if the designer prefers this. Another thing about substance planetary systems: the planets can mesh with (and revolve around) both fixed and rotating external gears simultaneously, hence a ring gear isn't essential.
Planet gears, for his or her size, engage a lot of teeth as they circle the sun equipment – therefore they can simply accommodate many turns of the driver for each result shaft revolution. To execute a comparable decrease between a standard pinion and gear, a sizable gear will need to mesh with a fairly small pinion.
Basic planetary gears generally offer reductions as high as 10:1. Compound planetary systems, which are far more elaborate compared to the simple versions, can provide reductions many times higher. There are apparent ways to further reduce (or as the case could be, increase) rate, such as for example connecting planetary phases in series. The rotational result of the initial 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 right into a planetary teach. For example, the high-rate power might go through an ordinary fixedaxis pinion-and-gear set before the planetary reducer. This kind of a configuration, called a hybrid, may also be favored as a simplistic alternative to additional planetary phases, or to lower insight speeds that are too high for some planetary units to take care of. It also provides an offset between the input and result. If a right angle is needed, bevel or hypoid gears are occasionally attached to an inline planetary program. Worm and planetary combinations are rare because the worm reducer alone delivers such high changes in speed.
