With single spur gears, a set of gears forms a gear stage. If you connect several equipment pairs one after another, that is known as a multi-stage gearbox. For every gear stage, the direction of rotation between your drive shaft and the result shaft is certainly reversed. The entire multiplication factor 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 gradual or a ratio to fast. In the majority of applications ratio to slower is required, because the drive torque is multiplied by the overall multiplication aspect, unlike the drive quickness.
A multi-stage spur gear can be realized in a technically meaningful way up to gear ratio of approximately 10:1. The reason for this is based on the 
ratio of the number of the teeth. 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 extremely easy to realize.
A two-stage gearbox or a three-stage gearbox may be accomplished by just increasing the distance of the ring gear and with serial arrangement of several 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 example. Instead of the drive shaft the planetary carrier contains the sun equipment, which drives the next planet stage. A three-stage gearbox is usually obtained through increasing the length of the ring gear and adding another world stage. A tranny ratio of 100:1 is obtained using individual ratios of 5:1, 5:1 and 4:1. Basically, all person ratios could 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 result shaft is always the same, so long as the ring equipment or casing 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 leaner than with a ratio of 20:1. In order to counteract this situation, the actual fact that the power loss of the drive stage is usually low must be taken into factor when working with multi-stage gearboxes. That is achieved by reducing gearbox seal friction loss or having a drive stage that’s geometrically smaller, for example. This also decreases the mass inertia, which is usually 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 as well the overall multiplication factor is the product of the average person ratios. Depending on the kind of gearing and the kind of bevel gear stage, the drive and the output can rotate in the same direction.
Benefits of multi-stage gearboxes:
Wide variety of ratios
Continuous 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 degree of efficiency
The automated transmission system is quite crucial for the high-speed vehicles, where in fact the planetary or epicyclic gearbox is a standard feature. With the increase in design multi stage planetary gearbox intricacies of planetary gearbox, mathematical modelling has become complex in nature and therefore there is a dependence on modelling of multistage planetary gearbox including the shifting scheme. A random search-centered synthesis of three degrees of freedom (DOF) high-quickness planetary gearbox has been presented in this paper, which derives an efficient gear shifting mechanism through designing the tranny schematic of eight velocity gearboxes compounded with four planetary equipment sets. Furthermore, by using lever analogy, the tranny power flow and relative power effectiveness have been decided to analyse the gearbox design. A simulation-based tests and validation have already been performed which show the proposed model is usually efficient and produces satisfactory change quality through better torque characteristics while shifting the gears. A fresh heuristic method to determine suitable compounding arrangement, predicated 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) due to their advantages of high power density and huge reduction in a small quantity [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 first literatures [3-5], the vibration structure of some example planetary gears are identified using lumped-parameter models, but they didn’t provide general conclusions. Lin and Parker [6-7] formally discovered and proved the vibration structure of planetary gears with equal/unequal planet spacing. They analytically categorized all planetary gears settings into exactly three groups, rotational, translational, and world modes. Parker [8] also investigated the clustering phenomenon of the three setting types. In the latest literatures, the systematic classification of modes had been carried into systems modeled with an elastic continuum band equipment [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] 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 explanation including translational degrees of freedom, which allows thousands of kinematic combinations. They mathematically proved that the modal characteristics of compound planetary gears had been analogous to a simple, 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 turbine [16].
According to the aforementioned versions and vibration structure of planetary gears, many researchers worried the sensitivity of the natural frequencies and vibration settings 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 equipment natural 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 substance planetary gears. They proposed closed-type expressions for the eigensensitivities to model parameter variations according to the well-defined vibration setting properties, and established the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary equipment eigenvalues. They used the organized vibration modes to show that eigenvalue loci of different setting types always cross and the ones of the same mode type veer as a model parameter is varied.
However, most of the current studies just referenced the technique used for single-stage planetary gears to investigate the modal features of multi-stage planetary gears, as the differences between these two types of planetary gears had been ignored. Due to the multiple degrees of freedom in multi-stage planetary gears, more descriptive division of natural frequencies must analyze the impact of different program parameters. The aim of this paper is usually to propose an innovative way of analyzing the coupled modes in multi-stage planetary gears to investigate the parameter sensitivities. Purely rotational amount of freedom models are used to simplify the analytical investigation of equipment vibration while keeping the primary dynamic behavior generated by tooth mesh forces. In this paper, sensitivity of natural 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 metal, 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 linking with couplings, input shafts, output shafts
The planetary equipment is a special type of gear drive, where the multiple world gears revolve around a centrally arranged sunlight gear. The planet gears are installed on a planet carrier and engage positively within an internally toothed ring gear. Torque and power are distributed among several planet gears. Sun gear, planet carrier and band gear may either be driving, driven or fixed. Planetary gears are used in automotive structure and shipbuilding, aswell 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 contains two planet gear sets, each with three planet gears. The ring equipment of the 1st stage is coupled to the earth carrier of the next 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 group of weights. The set of weights is elevated with a crank. A ratchet stops the weight from accidentally escaping. A clamping roller freewheel enables free further rotation following the weight offers been released. The weight is definitely caught by a shock absorber. A transparent protective cover stops accidental contact with the rotating parts.
To be able to determine the effective torques, the drive 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 right to a Computer via USB. The data acquisition software is included. The 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 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
pressure measurement on different gear phases 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
sunlight gears: 24-tooth, d-pitch circle: 48mm
world 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 phase; 120V, 60Hz, 1 phase
UL/CSA optional
he most basic type of planetary gearing involves three sets of gears with different levels of freedom. Planet 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 fixed. The concentricity of the earth grouping with sunlight and ring gears implies that the torque carries through a straight line. Many power trains are “comfortable” lined up straight, and the absence of offset shafts not only decreases space, it eliminates the necessity to redirect the power or relocate other parts.
In a simple planetary setup, input power turns sunlight gear at high velocity. The planets, spaced around the central axis of rotation, mesh with the sun as well as the fixed ring gear, so they are pressured to orbit as they roll. All of the planets are mounted to a single rotating member, called a cage, arm, or carrier. As the earth carrier turns, it delivers low-speed, high-torque output.
A fixed component isn’t constantly essential, though. In differential systems every member rotates. Planetary arrangements such as this accommodate a single output driven by two inputs, or a single input generating two outputs. For example, the differential that drives the axle within an automobile 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 basic principle as parallel-shaft systems.
Even a simple planetary gear train offers two inputs; an anchored ring gear represents a constant input of zero angular velocity.
Designers can proceed deeper with this “planetary” theme. Compound (as opposed to basic) 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 numbers, as can the gears they mesh with. Having such options significantly expands the mechanical opportunities, and allows more reduction per stage. Compound planetary trains can easily be configured therefore the world carrier shaft drives at high rate, while the reduction problems from the sun shaft, if the developer prefers this. One more thing about compound 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 his or her size, engage a lot of teeth as 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 typical pinion and gear, 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 far more elaborate compared to the simple versions, can offer reductions often higher. There are obvious ways to additional reduce (or as the case may be, increase) acceleration, such as connecting planetary stages in series. The rotational result of the first stage is from the input of the next, and the multiple of the individual ratios represents the ultimate reduction.
Another option is to introduce regular gear reducers into a planetary teach. For example, the high-velocity power might go through an ordinary 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 levels, or to lower input speeds that are too much for some planetary units to take care of. It also provides an offset between your input and output. If a right angle is needed, bevel or hypoid gears are sometimes mounted on an inline planetary program. Worm and planetary combinations are uncommon since the worm reducer alone delivers such high changes in speed.