With single spur gears, a couple of gears forms a gear stage. In the event that you connect several gear pairs one after another, this is referred to as a multi-stage gearbox. For every gear stage, the direction of rotation between your drive shaft and the result shaft is definitely reversed. The entire multiplication aspect 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 sluggish is required, because the drive torque is usually multiplied by the entire multiplication factor, unlike the drive rate.
A multi-stage spur gear could be realized in a technically meaningful method up to gear ratio of approximately 10:1. The reason behind this is based on the ratio of the number of tooth. From a ratio of 10:1 the driving gearwheel is extremely small. This has a negative effect on the tooth geometry and the torque that is getting transmitted. With planetary gears a multi-stage gearbox is extremely easy to realize.
A two-stage gearbox or a three-stage gearbox can be achieved by just increasing the space of the ring gear and with serial arrangement of many individual planet stages. A planetary equipment with a ratio of 20:1 can be manufactured from the individual ratios of 5:1 and 4:1, for example. Instead of the drive shaft the planetary carrier provides the sun equipment, which drives the next world stage. A three-stage gearbox is certainly obtained by way of increasing the space of the ring equipment and adding multi stage planetary gearbox another planet 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 sizable number of ratio options 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 result shaft is usually the same, so long as the ring equipment or housing 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 leaner than with a ratio of 20:1. In order to counteract this scenario, the actual fact that the power lack of the drive stage is certainly low should be taken into account when using multi-stage gearboxes. That is attained by reducing gearbox seal friction reduction or having a drive stage that is geometrically smaller, for example. This also decreases the mass inertia, which is certainly advantageous in dynamic 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 angle gearbox a bevel gear and a planetary gearbox are simply combined. Here too the entire multiplication factor may be the product of the individual ratios. Depending on the type 
of gearing and the kind of bevel gear stage, the drive and the output can rotate in the same path.
Advantages 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 range 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 quite crucial for the high-speed vehicles, where in fact the planetary or epicyclic gearbox is a typical feature. With the increase in design intricacies of planetary gearbox, mathematical modelling has become complex in nature and for that reason there is a dependence on modelling of multistage planetary gearbox like the shifting scheme. A random search-based synthesis of three degrees of freedom (DOF) high-speed planetary gearbox offers been presented in this paper, which derives an efficient gear shifting mechanism through designing the transmission schematic of eight quickness gearboxes compounded with four planetary gear sets. Furthermore, with the aid of lever analogy, the transmitting power circulation and relative power effectiveness have been established to analyse the gearbox design. A simulation-based tests and validation have been performed which display the proposed model is effective and produces satisfactory shift quality through better torque characteristics while shifting the gears. A new heuristic method to determine suitable compounding arrangement, predicated on mechanism enumeration, for designing a gearbox layout is proposed here.
Multi-stage planetary gears are trusted in many applications such as for example automobiles, helicopters and tunneling uninteresting machine (TBM) due to their advantages of high power density and large reduction in a little quantity [1]. The vibration and noise problems of multi-stage planetary gears are always 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 recognized using lumped-parameter models, however they didn’t provide general conclusions. Lin and Parker [6-7] formally determined and proved the vibration structure of planetary gears with equal/unequal planet spacing. They analytically classified all planetary gears modes into exactly three categories, 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 modes were carried into systems modeled with an elastic continuum ring gear [9], helical planetary gears [10], herringbone planetary gears [11], and high speed gears with gyroscopic results [12].
The natural frequencies and vibration settings of multi-stage planetary gears also have received attention. Kahraman [13] founded a family of torsional dynamics versions for compound planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic model of compound planetary gears of general explanation including translational degrees of freedom, which allows an infinite number of kinematic combinations. They mathematically proved that the modal characteristics of substance planetary gears had been analogous to a straightforward, single-stage planetary gear program. Meanwhile, there are plenty of researchers concentrating on the nonlinear dynamic features of the multi-stage planetary gears for engineering applications, such as TBM [15] and wind mill [16].
According to the aforementioned models and vibration structure of planetary gears, many experts concerned the sensitivity of the organic frequencies and vibration settings to program parameters. They investigated the result of modal parameters such as for example tooth mesh stiffness, planet bearing stiffness and support stiffness on planetary gear natural frequencies and vibration settings [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-type expressions for the eigensensitivities to model parameter variants 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 utilized the organized vibration modes showing that eigenvalue loci of different setting types often cross and those of the same mode type veer as a model parameter is usually varied.
However, many of the current studies only referenced the method used for single-stage planetary gears to investigate the modal features of multi-stage planetary gears, while the differences between both of these types of planetary gears were ignored. Because of the multiple levels of freedom in multi-stage planetary gears, more descriptive division of natural frequencies must analyze the impact of different system parameters. The aim of this paper is certainly 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 gear vibration while keeping the primary 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 can be found 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, based 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 gear is a special type of gear drive, in which the multiple planet gears revolve around a centrally arranged sunlight gear. The planet gears are mounted on a planet carrier and engage positively within an internally toothed ring equipment. Torque and power are distributed among several planet gears. Sun equipment, planet carrier and ring gear may either be driving, driven or fixed. Planetary gears are found 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 world gears. The ring gear of the 1st stage is definitely coupled to the earth carrier of the next stage. By fixing person gears, you’ll be able to configure a total of four different tranny ratios. The gear is accelerated via a cable drum and a adjustable group of weights. The set of weights is elevated with a crank. A ratchet prevents the weight from accidentally escaping. A clamping roller freewheel enables free further rotation following the weight provides been released. The weight can be 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 acceleration sensors on all drive gears permit the speeds to become measured. The measured ideals are transmitted directly to a Computer via USB. The info acquisition software is roofed. The angular acceleration can 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
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 after the weight has been released
shock absorber for weight
transparent protective cover
push measurement on different gear phases via 3 bending pubs, 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
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 stage; 120V, 60Hz, 1 phase
UL/CSA optional
he most basic type 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 gear binds the planets externally and is completely set. The concentricity of the earth grouping with sunlight and ring gears implies that the torque bears through a straight line. Many power trains are “comfortable” lined up straight, and the absence of offset shafts not only reduces space, it eliminates the necessity to redirect the energy or relocate other parts.
In a simple planetary setup, input power turns the sun gear at high rate. 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 installed to an individual rotating member, called 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 like this accommodate a single result driven by two inputs, or an individual input driving two outputs. For example, the differential that drives the axle in an car is 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 theory as parallel-shaft systems.
A good simple planetary gear train offers two inputs; an anchored band gear represents a constant input of zero angular velocity.
Designers can proceed deeper with this “planetary” theme. Compound (instead of basic) planetary trains have at least two planet gears attached in range to the same shaft, rotating and orbiting at the same acceleration while meshing with different gears. Compounded planets can have different tooth figures, as can the gears they mesh with. Having this kind of options significantly expands the mechanical opportunities, and allows more reduction per stage. Compound planetary trains can easily be configured so the planet carrier shaft drives at high speed, while the reduction issues from the sun shaft, if the developer prefers this. Another thing about compound planetary systems: the planets can mesh with (and revolve around) both fixed and rotating external gears simultaneously, hence a ring gear is not essential.
Planet gears, for his or her size, engage a lot of teeth because they circle the sun equipment – therefore they can simply accommodate numerous turns of the driver for every output shaft revolution. To perform a comparable reduction between a typical pinion and gear, a sizable gear will need to mesh with a rather small pinion.
Simple planetary gears generally provide 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 apparent ways to further decrease (or as the case may be, increase) velocity, such as connecting planetary phases in series. The rotational output of the initial stage is from the input of another, and the multiple of the average person ratios represents the ultimate reduction.
Another option is to introduce standard gear reducers into a planetary teach. For example, the high-speed power might pass through an ordinary fixedaxis pinion-and-gear set prior to the planetary reducer. This kind of a configuration, known as a hybrid, may also be preferred as a simplistic alternative to additional planetary stages, or to lower insight speeds that are too much for a few planetary units to take care of. It also has an offset between the input and output. If a right angle is necessary, bevel or hypoid gears are sometimes attached to an inline planetary system. Worm and planetary combinations are uncommon since the worm reducer by itself delivers such high adjustments in speed.