Mechanical Eng

This paper presents a wear process analysis of piston-cylinder set in internal combustion engines.Piston mechanism is a very important factor in the proper lubrication of the engine, but also a potential cause of increased consumption of oil. There are very important kinematic tribological properties of piston mechanisms in this regard. From the point of reliability and functionality, critical parts of this circuit are the piston rings. Wear is most pronounced in the first piston ring, since it is exposed to the highest pressure and temperature, as well as the direct impact of fuel and combustion products. The intensity of wear of piston cylinder set depends on many factors, but the most influential ones are: construction, materials used for the production of the parts of this assembly, production technology and conditions of use. ARTICLE HISTORY Received 02 Mart 2016 Accepted 24 Mart 2016 Available online 30 June 2016

The currently used method to calculate radius of curvature of a cylindrical cam's planar expansion pitch curve produces errors. Therefore, there is an urgent need to find an accurate method for cylindrical cam design. This research utilizes the three-dimensional expansion curve coordinates of the follower's motion track and establishes the planar expansion pitch curve equation with the consideration of deviation angle, which can be easily used to analyze and design an oscillating follower cylindrical cam. The deduced equation of radius of curvature is based on motion law of the mechanism and prime cylinder radius of the cam. The relation curve between minimum radius of curvature and prime cylinder radius, which takes into consideration that planar expansion pitch curve varies with prime cylinder radius in the event of certain motion law, is described by MATLAB, and specific minimum radius of prime cylinder is generated for each allowable radius of curvature according to the relation curve. Thus, geometric parameters of a cylindrical cam can be designed. The feasibility of our methodology is validated with a specific example.

The main purpose of this work is to present a complete kinematic analysis of the roller motion in translating cam-follower mechanisms with translating roller followers. The main kinematic variables of the roller are the angular velocity and angular acceleration. These quantities are deduced in a general form, in such a way they can be easily used for different cam laws. Furthermore, the influence of the functioning cam-follower parameters can also be included. Finally, an example of application is offered to analyze and discuss the main procedures considered in this work.

This article presents the automation of elliptical trammel mechanism by applying rack and pinion and DC Motor arrangement on the rod of the trammel which moves on the channel. The power supply is done by batteries and the entire system is carried out to have its operation by making ellipses of varying sizes. Moreover, a compass system attached at the end of the pinion makes it easy to fix and remove the cutting tools of every kind. Equations relating the position of two sliders with the position of drawing or cutting element provided at the end of connecting rod are derived. The results are experimentally verified by fabricating an elliptical trammel and drawing ellipses from it. The sliders of the mechanism move perpendicular to each other and the drawing or cutting element produces the ellipse on the required surface and of the required major and minor axes which in turn provides a very convenient mechanism for cutting out elliptical pieces of whatever sizes out of any kind of mat...

Numerical analysis of contact stresses at rotational elements of gerotor pumps with fixed position of shafts axis and with driving rotor acting as internal element, is presented in this paper. The basic characteristics and principles of functioning of this type of pumps are explained and review of researches in the area of numerical methods and developments and design optimizations of those pumps are presented. The basic assumptions, limitation and input values are defined in order to determine maximal stresses, numerical analysis of contact stresses, which are caused by transmitting of torque from internal to external gear. The obtained results of research contact stresses by numerical and analytical method are graphical presentations. The comparisons of results for better understanding of its deviations also were performed. ARTICLE HISTORY Received: 03 February 2016 Accepted: 17 February 2016 Available online: 30 june 2016

At a high frequency of vibration; the cam of a vibrator always encounters the issue of jamming or the follower rolling off or losing contact with the cam when the appropriate design is not carried out. This study, therefore, developed the shape of the cam profile of mechanical yam vibrator using cycloid motion in the South. Displacement equations from the base circle to the cam profile were developed to obtain the shape of the cam using cycloid motion. A vibrometer was used to evaluate the developed 5 mm, 10 mm, and 20 mm cam sizes installed in a mechanical yam vibrator. The maximum displacement recorded for 5 mm, 10 mm and 20 mm cam sizes were 4.47 mm, 8.71 mm, and 14.54 mm respectively for low (1-5 Hz) frequency; 4.58 mm, 8.84 mm and 16.34 mm respectively for medium (60-100 Hz) frequency; and 4.66 mm, 9.09 mm and 17.30 mm respectively for high (150-200 Hz) frequency. This study shows that a cycloid cam would operate smoothly at low, medium, and high frequencies of vibration and function properly for frequency and displacement of vibration up to 200 Hz and 20 mm respectively without jamming and failing. A cycloid cam is therefore recommended for low, medium, and high frequencies motion of vibration.

Grant:. VEGA 1/0515/13 Název grantu: Draft design layout and architecture of intelligent implants Oborové zaměření: JR Other machinery industry © GRANT Journal, MAGNANIMITAS Assn. Abstrakt The harmonic toothed gear transmissions undoubtedly are a prospective technology. It is about spur gearing where the meshing is achieved by the flexible deformation of one of the wheels. As a result of this deformation the shape of the flexible wheel changes from its original state resulting in incorrect meshing with the teeth of the opposite profile wheel. The deformation of the shape of the flexible wheel is the result of collision and interference, as well as the contact rate, occurring during the meshing of the flexible wheel with the rigid one. This effects the wearing, and results in an increase in the overall damage and consequently the lifespan of the harmonic gears. That is the reason for the teeth of the rigid wheel to be of an enveloping line of flexible cogs.

At a high frequency of vibration; the cam of a vibrator always encounters the issue of jamming or the follower rolling off or losing contact with the cam when the appropriate design is not carried out. This study, therefore, developed the shape of the cam profile of mechanical yam vibrator using cycloid motion in the South. Displacement equations from the base circle to the cam profile were developed to obtain the shape of the cam using cycloid motion. A vibrometer was used to evaluate the developed 5 mm, 10 mm, and 20 mm cam sizes installed in a mechanical yam vibrator. The maximum displacement recorded for 5 mm, 10 mm and 20 mm cam sizes were 4.47 mm, 8.71 mm, and 14.54 mm respectively for low (1 – 5 Hz) frequency; 4.58 mm, 8.84 mm and 16.34 mm respectively for medium (60 – 100 Hz) frequency; and 4.66 mm, 9.09 mm and 17.30 mm respectively for high (150 – 200 Hz) frequency. This study shows that a cycloid cam would operate smoothly at low, medium, and high frequencies of vibration ...

1Assistant Professor, Mechanical Engineering, Indore Institute of Science and Technology, Indore 2Assistant Professor, Mechanical Engineering, Shri G.S. Institute of Technology and Science, Indore --------------------------------------------------------------------------***----------------------------------------------------------------------Abstract This paper presents studies related to engine tribology in internal combustion engine. Friction loss is the main portion of the energy consumption developed in an engine. The friction loss is made up of the friction between the piston and the cylinder walls, piston rings and the cylinder wall, and between the crankshaft and camshaft and their bearings, as well as by the loss incurred by driving the essential accessories, such as the water pump, ignition unit etc. Lubricants are used to reduce the friction and wear and fuel consumption, increased power output of the engine, reduced oil consumption, a reduction in exhaust emissions in the...

This article deals with the synthesis of a ten-link tooth-lever differential transmission mechanism. The article contains an analytical review of modern scientific research on the synthesis of tooth-lever differential transmission mechanisms of roller machines with a variable center distance of the working shafts; a method for the synthesis of toothlever differential transmission mechanisms of roller machines with a variable center distance of the working shafts described on the example of a ten-link tooth-lever differential transmission mechanism; the conditions for the synthesis of the mechanism given and substantiated when this mechanism is used in a roller machine; one of its working shafts has the ability to rotate about its own axis, and the second working shaft, in addition to rotation about its own axis, has the ability to move relative to the first working shaft along a line passing through the center the axes of rotation of both working shafts; the geometric synthesis of t...

In this study, Nano-composites have been synthesized in which PMMA is the matrix material and calcium carbonate nanoparticles as the filler by In-situ polymerization reaction. Nano-CaCO 3 added during polymerization and the quantity of nano-CaCO 3 varied as 0.2, 0.4 and 0.6 wt. % of monomer quantity. The Nano-composites were prepared at three distinct stirring speeds 600, 800, 1000 rpm in order to observe the property with respect to stirring speeds. XRD gram depicts that the presence of nano-CaCO 3 has given crystalline nature to Nano-composites. The effects of different concentrations of nano-CaCO 3 loading on PMMA morphology were studied by using scanning electron microscope (SEM). The mechanical property is increasing with the stirring speed and concentration. Relative to neat PMMA a 62% increase in impact strength were observed in PMMA based Nano-composites using 0.6 wt.% nano-CaCO 3 .

PMMA/CaCO 3 nanocomposites have been fabricated by in-situ polymerization. The influence of concentration and stirring speed on tensile strength have been studied. The experimental results were optimized using Taguchi's approach. L9 Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio and the analysis of variance (ANOVA) are employed to find the optimal input parameter levels and to analyze the effect of these parameters on tensile strength. Experimental results showed that tensile strength PMMA/CaCO 3 nanocomposites increased up to 53 % at 0.6 wt. % CaCO 3 and 1000 rpm in comparison to corresponding pure PMMA. The experimental results and various statistical approaches namely, Taguchi methods, Conceptual S/N ratio and drew similar conclusions. The ANOVA analysis showed that speed is more dominant in comparison to concentration.

A translating cam driven by an offset slider-crank mechanism has varying velocity, and the follower motion can be arbitrarily chosen for only the forward or the return stroke of the translating cam. By employing the concept of velocity instant center, the cam profile, the path of cutter, the pressure angle and the radius of curvature of the cam can be expressed parametrically, and the follower motion of the remaining stroke can be analyzed analytically. The cam profile has concave, convex and flat portions.

In scope of this study, main parameters of cam profile are determined. Also, their effects on cam performance are examined starting with valve lift, velocity, acceleration curve. In order to be seen clearly cam behavior and obtain to needed smooth curve thanks to less jerk of cam follower, different valve lifts are calculated but more importantly one of the most critical design criteria on cam profile, acceleration jump as undesired influence, is investigated how to reduce & avoid. Primarily, relations related base circle & nose radius of cam profile, maximum lift of cam follower, lift angle of cam follower and acceleration jump are considered in terms of minimum acceleration jump, continuous contact, valve spring force & contact force-stress. Especially, determination of right valve spring stiffness is significant & affects other main parameters so it is plotted graphs of sudden acceleration change and described how it should be analyzed by analytical & using Matlab. .

Numerical analysis of contact stresses at rotational elements of gerotor pumps with fixed position of shafts axis and with driving rotor acting as internal element, is presented in this paper. The basic characteristics and principles of functioning of this type of pumps are explained and review of researches in the area of numerical methods and developments and design optimizations of those pumps are presented. The basic assumptions, limitation and input values are defined in order to determine maximal stresses, numerical analysis of contact stresses, which are caused by transmitting of torque from internal to external gear. The obtained results of research contact stresses by numerical and analytical method are graphical presentations. The comparisons of results for better understanding of its deviations also were performed. ARTICLE HISTORY Received: 03 February 2016 Accepted: 17 February 2016 Available online: 30 june 2016

To study various types of kinematics links, pairs, chains & Mechanisms. 3-7 2 To study inversions of 4 Bar Mechanisms, Single & double slider crank mechanisms. 8-10 3 To study various types of steering mechanisms. 11-13 4 To determine the Coriolli's Component of Acceleration at various speeds of rotation and water flow rates 14-17 5 To study the pressure profile of lubricating oil at various conditions of load and speed (i) To measure the frictional torque & power transmitted. (ii) To plot the Cartesian pressure curve. 18-20 6 To study the effect of varying the mass of central sleeve for Porter and Proell governors. 21-23 7 To study the effect of sleeve and height of watt governor 24-25 8 Demonstration of whirling phenomenon 26-27 Total Hours 20 2 EXPERIMENT NO.1 OBJECT :-To study various types of kinematics links, pairs, chains & Mechanisms. APPARATUS USED:-Kinematics links, pairs, chains & Mechanisms. THEORY:-A mechanism is made of a number of resistant bodies out of which some may have motions relative to the others. A resistant body or a group of resistant bodies with rigid connections preventing their relative movement is known as a link. A link also known as kinematic link or element. Examples :-A slider-crank mechanism consists of four links: frame and guides, crank connecting rod and slider, the crank link may have crankshaft and flywheel also, forming one link having no relative motion of these. CLASSIFICATIONS OF LINKS:-1. Rigid link-In this type of link there is no deformation while transmitting the motion. Motion between the piston and crank can be considered as a rigid link. 2. Flexible link-In this type of link there is partial deformation while transmitting the motion. Belt drive is an example of flexible link. 3. Fluid link-In this type of link the motion is transmitted with the help of fluid pressure. Hydraulic brake is an example of fluid link. Kinematic links are in form of :-1. Singular 3.Ternary 2.Binary 4. Quaternary KINEMATIC PAIR:-A kinematic pair or simply a pair is a joint of two links having relative motion between them.

The gearing with changing transmission gear ratio are used as synchronization component and for specific parameters. The gearing with changing transmission gear ratio is used in the practice, even though the "standard" gearing with constant transmission gear ratio are used more often. This article describes how to optimize the design of pitch curves of non-circular gear for given parameters. The non-circular gearing is consisting of two identical gear wheels. For a nonstandard gearing was applied eccentric elliptical gear drive with continuously changing transmission gear ratio. The kinematic properties of this gearing are different from the properties of standard circular gears-spur gear. Thus, the gear ratio changes over the time of one revolution. The article is devoted to problems determining of the stress in a dangerous section of tooth foot using FEM.

Numerical analysis of contact stresses at rotational elements of gerotor pumps with fixed position of shafts axis and with driving rotor acting as internal element, is presented in this paper. The basic characteristics and principles of functioning of this type of pumps are explained and review of researches in the area of numerical methods and developments and design optimizations of those pumps are presented. The basic assumptions, limitation and input values are defined in order to determine maximal stresses, numerical analysis of contact stresses, which are caused by transmitting of torque from internal to external gear. The obtained results of research contact stresses by numerical and analytical method are graphical presentations. The comparisons of results for better understanding of its deviations also were performed. ARTICLE HISTORY Received: 03 February 2016 Accepted: 17 February 2016 Available online: 30 june 2016

Quick Return Mechanisms (QRMs) are one of the essential accessories used in machine tools which involve reciprocating cutting action with a quick return stroke and a constant angular velocity of driving crank. The aim of this work was to simulate, design and construct a prototype of a QRM that can be used for demonstration and instrumentation. The QRM was simulated using Solidworks and a prototype was developed from the simulated results. The experiment was conducted using the prototype. The kinematic simulation of the Solidworks model was compared with the kinematics of motion of the prototype. The result showed that the Percentage Stroke Length error was 0.36%. It was observed that, there was no significant difference in the simulated and experimental results, hence, the prototype can be used for demonstration and experimentation to assist students in understanding basic principles of the machine operation.

This paper presents a wear process analysis of piston-cylinder set in internal combustion engines.Piston mechanism is a very important factor in the proper lubrication of the engine, but also a potential cause of increased consumption of oil. There are very important kinematic tribological properties of piston mechanisms in this regard. From the point of reliability and functionality, critical parts of this circuit are the piston rings. Wear is most pronounced in the first piston ring, since it is exposed to the highest pressure and temperature, as well as the direct impact of fuel and combustion products. The intensity of wear of piston cylinder set depends on many factors, but the most influential ones are: construction, materials used for the production of the parts of this assembly, production technology and conditions of use. ARTICLE HISTORY Received 02 Mart 2016 Accepted 24 Mart 2016 Available online 30 June 2016

The introductory part presents the view of some other authors in connection with the subject matter of the present paper. It points out to the fact that there is only one approximate method of synthesis of single-disk cams with two oscillating roller followers known so far. This method produces a mechanism which, in certain positions, wobbles at the joint between the double roller follower and its cam. This paper demonstrates the possibility of achieving an exact synthesis for such mechanisms. It also infers the necessary and sufficient conditions for the existence of a single-disk cam with two oscillating rigidly connected roller followers. Starting from these conditions, the laws of motion that can be achieved are being discussed.

This paper presents an analytical approach for the analysis of a new working concept for variable delivery external gear machines. The proposed design principle encompasses all the advantages of conventional fixed displacement external gear machines, along with a simple mechanism to change the displaced flow per shaft revolution. The variation in the displaced flow is achieved by realizing a variable timing for the connections of each tooth space volume (volume between two adjacent teeth of the gears) with the inlet and outlet. This is achieved through a movable slider placed at the gear lateral sides. The position of the slider determines the amount of flow displaced by the unit per revolution. Analytical expressions which define the range of percentage variation in flow displacement that can be achieved based on a generic asymmetric design of the gears are presented. The paper presents a detailed analytical derivation for geometric displacement, flow delivered at the outlet and shaft torque required during operation as well as flow nonuniformity/pulsation. The analytical expressions were compared with proof of concept test. Experimental results were in line with the analytical prediction and show a 32% variation in displacement. These positive results show promising potentials for the working of a new concept for variable delivery external gear machine.

Commercial tools for measurement and analysis of noise and vibration signals have traditionally been very expensive. In the last decade, however, multi-channel measurement systems have become relatively inexpensive. The analysis functionality in most inexpensive instruments is limited. Therefore, many companies are using alternatives for post processing of measurement results. MATLAB is a platform that is popular for this purpose and which offers many advantages over dedicated, menu driven systems. The open functions in MATLAB assure flexibility and the possibility to modify functions for specific needs. In addition, a command based programming environment provides for traceability and quality assurance, including qualification of used algorithms, important aspects particularly in the aerospace industry. In the past, basic functions for physically scaled signal analysis and vibration analysis have had to be developed before taking full advantage of the MATLAB platform. In this paper...

Design of gears with asymmetric teeth that enables to increase load capacity, reduce weight, size and vibration level.. standard tool parameters and uses nonstandard tooth shapes to provide required performance for a particular custom application. This makes finite element analysis (FEA) more preferable than the Lewis equation for bending stress definition. This paper does not describe the FEA application for comprehensive stress analysis of the gear teeth. It sents the engineering method for bending stress balance and minimization.

Heavy duty diesel (HDD) construction equipment which includes bulldozer is important in infrastructure development. This equipment consumes large amount of diesel fuel and emits high level of carbon dioxide (CO2). The total emissions are dependent upon the fuel use, and the fuel use is dependent upon the productivity of the equipment. This paper proposes a methodology and tool for estimating CO2 emissions from bulldozer based on the productivity rate. The methodology is formulated by using the result of multiple linear regressions (MLR) of CAT's data for obtaining the productivity model and combined with the EPA's NONROAD model. The emission factors from NONROAD model were used to quantify the CO2 emissions. To display the function of the model, a case study and sensitivity analysis for a bulldozer's activity is also presented. MLR results indicate that the productivity model generated from CAT's data can be used as the basis for quantifying the total CO2 emissions for an earthwork activity.

In this paper, an attempt has been made to develop a stamping machine for making the labelling operation in any production line automatic. An inversion of the four bar chain with one link suitably shaped in the form of a stamp has been designed such that it labels each of the boxes present on the conveyor one by one. Though the stamping machine is not a new device and such devices have been made and are currently being used the world over, it is, the methodology of design used in this paper, which is rather unconventional. The mechanism has been designed graphically using the three position synthesis of four bar chain mechanism in which three positions of the coupler link of the mechanism have been fixed to carry out the synthesis. A prototype of the stamping machine has been fabricated and checked for smooth working.

In the cycloidal gear, the torque is transmitted to the planet gears via an eccentric shaft with central bearings mounted on it. A straight-line mechanism is used to output the torque from the planet gears to the output shaft, a mechanism which consists of rotational sleeves mounted on the pins rigidly connected to the output shaft disc. These sleeves roll off in the holes of the planetary wheel. The forces generated in the straight-line mechanism affect the distribution of forces in the cycloid gearing and the amount of force loading the central bearing. The article presents the influence of the number of bolts of the straight-line mechanism on the load distribution in the cycloidal gear. The research carried out with the simulation program has shown that the smaller the number of pins, the greater the fluctuation of the force acting in the central bearing and the greater unevenness of force distributions in the cycloidal gear. This unevenness may cause a decrease in fatigue life o...

One of the most critical element in the orbital manipulators are kinematic joints. Joints must be adapted to work in tough conditions of space environment and must ensure the greatest efficiency and work without backlash. At the Space Mechatronics and Robotics Laboratory (LMRS) of the Space Research Centre, PAS our team designed and built a lightweight kinematic pair based on a new concept. The new concept is based on the epicycloid two-stage gearbox with torque motor. In this paper we have focused on optimization of the joint design for space application. The optimization was focused on the minimization of the mass and backlash effects and on maximizing the joint efficiency.

Alat penukar kalor type pipa ganda merupakan salah satu jenis alat penukar kalor menggunakan aliran fluida panas dan dingin yang mana masing-masing mengalir secara berlawanan arah. Untuk air panasnya di bantu dengan menggunakan heater supaya dapat menghasilkan panas yang maksimal dan kedua aliran di bantu dengan media pompa sehingga airnya bisa mengalir secara beraturan. Untuk metode yang digunakan adalah metode literature dan pengambilan data secara langsung di laboratorium universitas 17 agustus 1945 jakarta. Dari hasil analisa untuk kapasitas alat penukar kalor type pipa ganda. (A) laju aliran energy panas (watt) : uji coba pertama, kedua, ketiga dan ke empat (8368), (10041), (11715), (13388). (B) koefisien perpindahan kalor menyeluruh (watt): uji coba pertama, kedua, ketiga, dan keempat(93,77), (93,33), (92,60), (92,15). (C) efektivitas(%): uji coba pertama, kedua, ketiga,dan keempat (10% , (12% (14% ,(16% . Dimana dari keempat pengujian tersebut yang paling efektivias adalah pengujian keempat karna panas yang di keluarkan
meningkat dan menghasilkan konduktivitas termal yang besar.

Gears are a simple but extraordinary invention. They are not a recent attainment although it is difficult to date their discovery. The oldest finding containing gears (more than 30) is the Antikythera mechanism, made at the end of the second century BC. The Antikythera was an ancient Greek analog computer, capable to follow the sun's and the moon's astronomical positions and to predict eclipses [8]. Given the great complexity of the object it is reasonable to assume that the gears' theory and technique were already highly developed at the time. The first chapter of Mechanical Problems (school of Aristotle, ca 280 BC), which mentions gears, seems to confirm this supposition. It refers to a pair of connected wheels and notes that the direction of rotation is reversed when a wheel drives another wheel. Another ancient device is the Chinese South Pointing Chariot, a sophisticated tool using a similar mechanism to modern cars differential. Some legends date it as far back as 2600 BC although the first well-documented evidences of its existence are much more recent (after 200 AD) [4, 17]. Surprisingly Nature too, in its ceaseless experimentation, has discovered gears. The nymphs of a small insect, the Issus coleoptratus, have small gear-like structures with inter-meshing teeth that synchronize the movement of their hind legs when they jump. These insects are among the fastest-accelerating creatures, reaching an acceleration of almost 400 g. Their movement is so fast that the nervous system alone can not balance the force impressed to the two legs. The bug can control the trajectory of its jumps only thanks to those natural cogwheels [2]. Nowadays humans use gears on a daily basis. They are present in virtually every device with moving parts: engines, bicycles, analog clocks, kitchen mixers, mills, bottle openers, various types of toys and countless other examples. Gears are also used in kinetic art. It is worth mentioning Machine with Concrete, by Arthur Ganson: it is a kinetic sculpture driven by an electric engine turning at about 200 revolutions per minute. The sculpture has 12 pairs of gears that reduce

In this paper a simulation of the cam actuator of a robotized gearbox is presented. The actuator is a barrel cam which moves a pin according to a prescribed motion law. The model of contact, between cam and follower, is based on a finite elements approach of the theory of beam on continuous elastic foundation, modified by the authors to include the effect of shear on the deformation and dynamic effects. The foundation modulus is computed using Hertz theory taking also into account the change of principal curvature values during the relative motion between cam and follower. This model has been embodied in a complete gear shifting simulation in order to compare the effects on contact forces, wear actions and shifting time of different cam profiles.

Rzeppa pilot-lever joint represents a classical solution to the problem of transmitting torque between angularly misaligned shafts. Homokineticity is one of the most important requirement in industrial applications. The Myard's theorem gives the geometrical conditions which ensure the satisfaction of such requirement. In this paper, two different original proofs of this theorem are offered. An algorithm for the optimal kinematic synthesis of the pilot-lever mechanism is then proposed. The pilot-lever mechanism is designed to minimize the maximum angle between the transmission and the homokinetic plane. Finally, a multi-body dynamic analysis of the Rzeppa pilot-lever joint is made by means of a commercial software. The modelling of contact conditions between the balls and the guides is discussed in particular. Finally, the contact forces between spheres and guides for different angles between input and output shafts are computed.

1 Introduction This paper presents research in kinematic analysis of spatial higher pairs. Higher pairs are common in mechanical design. Gears and cams are used in all types of mechanical systems. Ratchets, indexers, and other specialized pairs are used in low-torque precision ...

The worm gears are useful where the transmission ratio and the self-locking are needed (for particular gears). In the automotive industry, the worm gears are used in worm-and-roller steering gears, drives of the windshield wipers, wind-down car windows, etc. These gears have various versions, as a helical worm-gear and a globoidal worm-gear. The globoidal worm-gear, with rotary teeth was presented. This is an innovative idea connected with this type of gears. In the gear, the globoidal worm gear was used, and the classical worm wheel was replaced by the wheel with rotary teeth in the shape of the frustum of cone. The frustum of cone shape is needed because of minimization of the slippage between the teeth and the surface of the worm gear. The gear teeth have the helical shape. Rotation of the teeth, having appropriate angle of the conical surface, helps to minimize the slippage. In addition, the teeth are able to displace axially. In use, the teeth are pressed against the worm surfa...

The design of efficient and reliable gearing mechanism is governed, among other factors, by its ability to withstand the frictional contact condition and high bending stresses experienced at the tooth root. One of the major impediments facing designers is the effective drafting of gears to required configuration. For involutes spur gears, the geometry is tedious and time-consuming; and the geometric complexity increases with helical, bevel and worm gears. This study presents a model developed by utilizing the integration of VBA technology built in AutoCAD for the drafting of spur gear to standard configuration. The design was based on full-depth involute gears of pressure angles 14½°, 20°, and 25°; with module ranging between 0.3 and 25 mm, and number of teeth varying between 12 and 60. The algorithm employed the conventional manual drafting techniques by navigating the IDE of VBA with AutoCAD objects, properties, methods, events, and application of errors handling techniques that w...

In the second part of paper the results from the first part are applied to the cam mechanisms with knife-edge translating follower. First, a method for characterizing the tangency points fulfilling the actual constraints of the problem is identified. Applying this criterion, a set of equidistant points is generated on the whole geometrical locus of tangency points and the characteristics of approximating circles are found. Considering all replacement solutions, the kinematical analysis for all cam mechanisms with approximate profiles is made, choosing amid them the one performing the closest kinematical behavior to the exact cam mechanism.

We present two geometric descriptions of the net frictional force and moment between a rigid body and a planar surface on which it slides. The limit surface, from classical plasticity theory, is the surface in load space which bounds the set of all possible frictional forces and moments that can be sustained by the frictional interface. Zhukovskii's moment function (N. E. Zhukovskii,

The paper shows an analysis of two mechanisms that are typically used as function generators. The former consists of a pair of non-circular gears, which drives a slider-crank mechanism, the latter is a cam-follower system. Both mechanisms are designed to obtain a specific motion law. In this paper the proposed application is to generate a pulsating blood flow during cardiopulmonary bypass for cardiac surgery. The prescribed motion law can be obtained by a volumetric pump, which can be used to modulate the blood flow in external circulation machines. The reciprocating motion consists of a quick forward stroke, corresponding to the Systolic phase, and a slow return stroke, corresponding to the Diastolic phase. The study has been focused on specific transmission characteristics that are related to a mechanical blood pumping design. In particular, experimental tests have been analyzed to understand benefits and drawbacks for using non-circular gears and polynomial cams in pure mechanical transmissions with limited motion regulation but with specific prescribed motion law. The contribution of the paper can be recognized in comparing numerically and experimentally a traditional cam transmission with a non-circular gear solution to show proper operation feasibility for both solutions without using complex control equipment, even for a robust/reliable demanding application like a blood pumping system.

This paper presents the design procedures and algorithm to design a new type roller drive. The geometrical design is obtained by the coordinate transformation, kinematics and envelope theory. Four examples are presented and using CAD constructs the solid modeling to demonstrate the feasibility of this approach. This design model can be a useful reference as a design case for other tooth profiles.

Gearing is one of the most important rolling nodes in a cycloidal planetary transmission. It consists of gears whose outlines are created according to cycloidal curves and the rollers cooperating with them. The epicycloidal and hypocycloidal gearing can be distinguished. There are power losses during the transmission operation, due to the transmitted load and friction in the gearing. The paper presents an analytical method for determining losses in cycloidal gearing, taking into account the manufacturing deviations of the elements making this gearing. The analysis allowed determining the distribution of intertooth clearances and forces at the points of contact between the profiles and the rollers, and consequently the distribution of power losses in gearing. The distribution of intertooth forces was verified by elastooptic tests of the gears set with cycloidal gearing. The results of the calculations indicate that the influence of eccentricity changes on the distribution of intertoo...

This paper presents preliminary analytical and numerical procedures for the analysis of the motion of extensible belt/pulley systems. These procedures can be used to accurately predict the change in the belt velocity, tension force, normal force, friction force and the cross section deformations along the belt length at the steady state condition. The methods used in this paper relax the assumption of constant shear and internal moment along the belt length, leading to more accurate results as compared to the results obtained using previous models. The analytical solution obtained in this paper is validated by comparing it with the solution obtained using absolute nodal coordinate formulation (ANCF) finite elements. It is shown that considering the effect of the internal moment and assuming that the contact between the belt and the pulley has three stages lead to more realistic prediction of the belt system variables and more accurate values for the angles in the belt/pulley sliding zones. The change in the angular velocity of the driven pulley with respect to the driving pulley, the change in the cross section dimensions, and the belt stretch are predicted. The results obtained in this study also demonstrate that formulations presented in this paper lead to more accurate prediction for the belt tension, friction and normal forces. ANCF structural finite elements provide more general kinematic description that can be used to predict the cross section deformation and its coupling with the extension and bending of the belts and rubber chains.

Diesel engine and gearbox lubrication systems are normally supplied by gear pumps which are independently driven for large slow speed engines and stand-by duties but usually shaft driven for medium and high speed engines. Gear pumps are also used for fuel and oil transfer, boiler combustion systems and other duties. Most often they are used in the field of small flow rate (before 10 m 3 /h) and medium and high pressure. The pump parameters are almost completely determined by the gear train parameters. Analysis of the known methods of increasing the gear pump flow rate showed that today almost all known methods should be classified as extensive. Increased flow rate is provided by a proportional increase in the geometric dimensions of the gears and the pump. Advances in the gear manufacturing technology have led to decrease in the amount of gears, manufactured through cutting. Modern machinery utilizes gears manufactured through casting, stamping and sintering. Thus, one may avoid the otherwise obligatory link between the tooth profile and the parameters of the cutting tool-rack cutter, gear-shaper cutter and gear hobbing cutter. The use of milling machines with CNC (computer numerical control) enables the manufacturing of a random tooth profile. Therefore, the technological limitations that have led to the general use of the involute tooth system vanish [1-3]. In this regard, the topic of using epicycloids and hypocycloids for tooth profiling is brought forth. Confirmation is obtained for increase of 20% of the fluid volume in the tooth space of the gear pump with combined involute-cycloid tooth profile compared to involute tooth profile [4-7]. A characteristic defect of the gear pump is an increase in the diametrical clearance between the housing and the tops of the gear teeth due to their wear. During the repair, bore the pump housing and install new gears with an increased outer