With single spur gears, a pair of gears forms a gear stage. If you connect several equipment pairs one after another, this is known as a multi-stage gearbox. For each gear stage, the path of rotation between your drive shaft and the result shaft can be reversed. The entire multiplication aspect of multi-stage gearboxes is certainly 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 is a ratio to gradual or a ratio to fast. In nearly all applications ratio to slow is required, because the drive torque is multiplied by the entire multiplication factor, unlike the drive swiftness.
A multi-stage spur gear could be realized in a technically meaningful way up to a gear ratio of approximately 10:1. The reason behind this is based on the ratio of the amount of tooth. From a ratio of 10:1 the generating gearwheel is extremely small. This has a negative effect on the tooth geometry and the torque that is becoming 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 basically increasing the distance of the ring equipment and with serial arrangement of several individual planet phases. A planetary gear with a ratio of 20:1 could be manufactured from the average person ratios of 5:1 and 4:1, for instance. Rather than the drive shaft the planetary carrier provides the sun equipment, which drives the next planet stage. A three-stage gearbox can be obtained through increasing the space of the ring gear and adding another world stage. A transmission 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 big number of ratio options for multi-stage planetary gearboxes. The transmittable torque could be increased using extra planetary gears when carrying out this. The path of rotation of the drive shaft and the result shaft is at all times 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 lower 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 low must be taken into account when using multi-stage gearboxes. This is achieved 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 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 a right position gearbox a bevel equipment and a planetary gearbox are simply just combined. Here as well the overall multiplication factor may be 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 path.
Advantages of multi-stage gearboxes:
Wide variety of ratios
Constant 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 (compared to single-stage gearboxes):
More complex design
Lower amount of efficiency
The automated transmission system is very crucial for the high-speed vehicles, where the planetary or epicyclic gearbox is a standard feature. With the upsurge in style intricacies of planetary gearbox, mathematical modelling is becoming complex in character and for that reason there is a need for modelling of multistage planetary gearbox like the shifting scheme. A random search-centered synthesis of three levels of freedom (DOF) high-velocity planetary gearbox has been shown in this paper, which derives an efficient gear shifting mechanism through designing the tranny schematic of eight velocity gearboxes compounded with four planetary gear sets. Furthermore, by making use of lever analogy, the transmission power movement and relative power efficiency have been identified to analyse the gearbox style. A simulation-based examining and validation have been performed which show the proposed model is efficient and produces satisfactory change quality through better torque features while shifting the gears. A new heuristic method to determine suitable compounding arrangement, based 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 boring machine (TBM) because of their benefits of high power density and huge reduction in a small volume [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 framework of some example planetary gears are recognized using lumped-parameter models, but they didn’t give 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 groups, rotational, translational, and world settings. Parker [8] also investigated the clustering phenomenon of the three mode types. In the latest literatures, the systematic classification of settings were carried into systems modeled with an elastic continuum band gear [9], helical planetary gears [10], herringbone planetary gears [11], and high swiftness gears with gyroscopic effects [12].
The organic frequencies and vibration modes of multi-stage planetary gears have also received attention. Kahraman [13] established a family group of torsional dynamics models for substance planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic model of substance planetary gears of general explanation including translational examples of freedom, which enables 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 system. Meanwhile, there are many researchers concentrating 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 researchers concerned the sensitivity of the natural frequencies and vibration modes to system parameters. They investigated the effect of modal parameters such as tooth mesh stiffness, planet bearing stiffness and support stiffness on planetary equipment 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 established the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary equipment eigenvalues. They used the structured vibration modes showing that eigenvalue loci of different setting types constantly cross and those of the same mode type veer as a model parameter is varied.
However, many of the existing studies only 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. Because of the multiple examples of freedom in multi-stage planetary gears, more detailed division of organic frequencies must analyze the impact of different program parameters. The aim of this paper is certainly to propose an innovative way of analyzing the coupled modes in multi-stage planetary gears to analyze the parameter sensitivities. Purely rotational amount of freedom models are accustomed 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 equipment 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 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 decrease, 95% at double reduction
5. Planetary gear arranged torque range: Low torque, middle torque, high torque
6. Easy linking with couplings, input shafts, result 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 installed on a world carrier and engage positively within an internally toothed band gear. Torque and power are distributed among a number of planet gears. Sun gear, planet carrier and band equipment may either be traveling, driven or set. Planetary gears are found 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 contains two planet gear units, each with three planet gears. The ring equipment of the first stage is usually coupled to the earth carrier of the second stage. By fixing person gears, it is possible to configure a total of four different transmitting ratios. The apparatus is accelerated with a cable drum and a adjustable group of weights. The group 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 offers been released. The weight is definitely captured by a shock absorber. A transparent protective cover prevents accidental contact with the rotating parts.
To be able to determine the effective torques, the power measurement measures the deflection of bending beams. Inductive acceleration sensors on all drive gears allow the speeds to become measured. The measured ideals are transmitted directly to a Personal computer via USB. The data 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 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 enables free further rotation following the weight has been released
shock absorber for weight
transparent protective cover
push measurement on different equipment 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
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 stage; 120V, 60Hz, 1 phase
UL/CSA optional
he most basic form of planetary gearing involves three sets of gears with different levels of freedom. World gears rotate around axes that revolve around a sun gear, which spins in place. A ring equipment binds the planets on the outside and is completely set. The concentricity of the earth grouping with the sun and ring gears means that the torque carries through a straight series. Many power trains are “comfortable” prearranged straight, and the lack of offset shafts not merely reduces space, it eliminates the need to redirect the energy or relocate other elements.
In a straightforward planetary setup, input power turns the sun gear at high velocity. The planets, spaced around the central axis of rotation, mesh with sunlight as well as the fixed ring gear, so they are forced to orbit as they roll. All the planets are installed to a single rotating member, known as a cage, arm, or carrier. As the planet carrier turns, it multi stage planetary gearbox delivers low-speed, high-torque output.
A set component isn’t generally essential, though. In differential systems every member rotates. Planetary arrangements like this accommodate a single output driven by two inputs, or a single input traveling two outputs. For instance, 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 theory as parallel-shaft systems.
A good simple planetary gear train provides two inputs; an anchored ring gear represents a continuous insight of zero angular velocity.
Designers can move deeper with this “planetary” theme. Compound (as opposed to simple) planetary trains have at least two planet gears attached in range to the same shaft, rotating and orbiting at the same quickness while meshing with different gears. Compounded planets can have got different tooth figures, as can the gears they mesh with. Having such options greatly expands the mechanical options, and allows more reduction per stage. Compound planetary trains can simply be configured so the planet carrier shaft drives at high rate, while the reduction problems from sunlight shaft, if the designer prefers this. One more thing about substance planetary systems: the planets can mesh with (and revolve around) both fixed and rotating exterior gears simultaneously, hence a ring gear isn’t essential.
Planet gears, for their size, engage a whole lot of teeth as they circle the sun gear – therefore they can easily accommodate several turns of the driver for each result shaft revolution. To perform a comparable decrease between a typical pinion and equipment, a sizable gear will have 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 than the simple versions, can provide reductions often higher. There are apparent ways to further reduce (or as the case could be, increase) speed, such as for example connecting planetary phases in series. The rotational output of the 1st stage is linked to the input of the next, and the multiple of the individual ratios represents the final reduction.
Another option is to introduce regular gear reducers into a planetary train. For example, the high-velocity 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 alternative to additional planetary phases, or to lower input speeds that are too high for a few planetary units to take care of. It also provides an offset between the input and output. If a right angle is necessary, bevel or hypoid gears are occasionally attached to an inline planetary program. Worm and planetary combinations are uncommon since the worm reducer by itself delivers such high changes in speed.
