With single spur gears, a pair of gears forms a gear stage. If you connect several gear pairs one after another, this is known as a multi-stage gearbox. For each gear stage, the path of rotation between the drive shaft and the result shaft can be reversed. The overall multiplication factor of multi-stage gearboxes can be 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 slower or a ratio to fast. In the majority of applications ratio to sluggish is required, because the drive torque is certainly multiplied by the overall multiplication 
element, unlike the drive quickness.
A multi-stage spur gear can be realized in a technically meaningful method up to a gear ratio of around 10:1. The reason for this is based on the ratio of the number of tooth. From a ratio of 10:1 the driving gearwheel is extremely little. This has a negative influence on the tooth geometry and the torque that is 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 many individual planet levels. A planetary equipment with a ratio of 20:1 can 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 equipment, which drives the next planet stage. A three-stage gearbox is certainly obtained by way 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 could be combined, which outcomes in a big number of ratio options for multi-stage planetary gearboxes. The transmittable torque could be increased using additional planetary gears when performing this. The direction of rotation of the drive shaft and the result shaft is constantly the same, so long as the ring equipment or casing is fixed.
As the number of equipment stages increases, the efficiency of the entire gearbox is reduced. With a ratio of 100:1 the effectiveness is leaner than with a ratio of 20:1. To be able to counteract this scenario, the fact that the power loss of the drive stage can be low should be taken into consideration when working with 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 definitely advantageous in dynamic applications. Single-stage planetary gearboxes will be the most efficient.
Multi-stage gearboxes may 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 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 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 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 style intricacies of planetary gearbox, mathematical modelling has become complex in character and therefore there is a dependence on modelling of multistage planetary gearbox like the shifting scheme. A random search-centered synthesis of three examples of freedom (DOF) high-speed planetary gearbox provides been offered in this paper, which derives a competent gear shifting system through designing the transmitting schematic of eight speed gearboxes compounded with four planetary equipment sets. Furthermore, with the aid of lever analogy, the transmitting power flow and relative power performance have been motivated to analyse the gearbox style. A simulation-based screening and validation have already been performed which show the proposed model is definitely effective and produces satisfactory shift quality through better torque features while shifting the gears. A new heuristic solution to determine suitable compounding arrangement, predicated on mechanism enumeration, for creating 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 quantity [1]. The vibration and noise complications of multi-stage planetary gears are at all times the focus of attention 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 framework of some example planetary gears are determined using lumped-parameter models, however they didn’t give general conclusions. Lin and Parker [6-7] formally recognized and proved the vibration framework of planetary gears with equal/unequal world spacing. They analytically categorized all planetary gears modes into exactly three types, rotational, translational, and planet modes. Parker [8] also investigated the clustering phenomenon of the three mode types. In the recent 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 swiftness gears with gyroscopic results [12].
The organic frequencies and vibration modes of multi-stage planetary gears have also received attention. Kahraman [13] set up a family of torsional dynamics versions 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 compound planetary gears had been analogous to a simple, single-stage planetary gear program. Meanwhile, there are various researchers focusing on the nonlinear dynamic features of the multi-stage planetary gears for engineering applications, such as for example TBM [15] and wind turbine [16].
Based on the aforementioned models and vibration framework of planetary gears, many experts concerned the sensitivity of the organic frequencies and vibration modes to program parameters. They investigated the effect of modal parameters such as tooth mesh stiffness, world bearing stiffness and support stiffness on planetary gear organic frequencies and vibration modes [17-19]. Parker et al. [20-21] mathematically analyzed the effects of style parameters on organic 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 according to 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 used 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 definitely varied.
However, the majority of of the current studies just referenced the method used for single-stage planetary gears to analyze the modal features of multi-stage planetary gears, while the differences between these two types of planetary gears were ignored. Because of the multiple examples of freedom in multi-stage planetary gears, more detailed division of organic frequencies are required to analyze the impact of different program parameters. The objective 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 gear vibration while keeping the primary dynamic behavior produced 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 established can combine the same or different ratios
3. Planetary gear set is available in plastic, sintered steel, 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 connecting with couplings, input shafts, output shafts
The planetary equipment is a special type of gear drive, where the multiple planet 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 equipment. Torque and power are distributed among many planet gears. Sun equipment, planet carrier and ring gear may either be generating, driven or set. Planetary gears are used 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 includes two planet gear units, each with three planet gears. The ring gear of the 1st stage is usually coupled to the planet carrier of the next stage. By fixing person gears, it is possible to configure a total of four different tranny ratios. The gear is accelerated via a cable drum and a variable group of weights. The set of weights is elevated with a crank. A ratchet helps prevent the weight from accidentally escaping. A clamping roller freewheel enables free further rotation following the weight offers been released. The weight is usually captured by a shock absorber. A transparent protective cover stops accidental connection with the rotating parts.
In order to determine the effective torques, the pressure measurement measures the deflection of bending beams. Inductive velocity sensors on all drive gears permit the speeds to end up being measured. The measured values are transmitted right 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 dynamic 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 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 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 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 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 collection. Many power trains are “comfortable” prearranged straight, and the absence of offset shafts not merely decreases space, it eliminates the necessity to redirect the energy or relocate other elements.
In a straightforward planetary setup, input power turns the sun gear at high swiftness. The planets, spaced around the central axis of rotation, mesh with the sun and also the fixed ring equipment, so they are pressured to orbit as they roll. All of the planets are installed to an individual rotating member, called a cage, arm, or carrier. As the earth carrier turns, it provides low-speed, high-torque output.
A set component isn’t usually essential, though. In differential systems every member rotates. Planetary arrangements such as this accommodate a single output powered by two inputs, or an individual input traveling two outputs. For instance, 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 equipment planetary systems operate along the same basic principle as parallel-shaft systems.
Even a simple planetary gear train provides two inputs; an anchored ring gear represents a continuous input of zero angular velocity.
Designers can proceed deeper with this “planetary” theme. Compound (as opposed to basic) planetary trains possess at least two world gears attached in collection to the same shaft, rotating and orbiting at the same rate while meshing with different gears. Compounded planets can possess different tooth amounts, as can the gears they mesh with. Having this kind of options greatly expands the mechanical options, and allows more decrease per stage. Compound planetary trains can simply be configured therefore the planet carrier shaft drives at high quickness, while the reduction issues from the sun shaft, if the designer prefers this. Another 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, because of their size, engage a whole lot of teeth as they circle the sun gear – therefore they can certainly accommodate several turns of the driver for every result shaft revolution. To perform a comparable decrease between a typical pinion and gear, a sizable gear will have to mesh with a rather 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 many times higher. There are apparent ways to additional reduce (or as the case could be, increase) speed, such as for example connecting planetary levels in series. The rotational output of the initial stage is linked to the input of another, and the multiple of the individual ratios represents the final reduction.
Another choice is to introduce standard gear reducers right into a planetary train. For instance, the high-acceleration power might go through an ordinary fixedaxis pinion-and-gear set prior to the planetary reducer. Such a configuration, known as a hybrid, is sometimes favored as a simplistic option to additional planetary phases, or to lower input 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 needed, bevel or hypoid gears are sometimes mounted on an inline planetary system. Worm and planetary combinations are rare since the worm reducer by itself multi stage planetary gearbox delivers such high changes in speed.
