Rigid Axle Research Articles

Metodologija za izbor elektromotora za pogon mini traktora zasnovana na efikasnosti

This article deals with the research and analysis of electric motors and their matched transmission systems within the context of a versatile electric mini-tractor designed for tasks such as street cleaning, urban park maintenance, and transportation of small loads. The primary objective of the research is to assess the strengths and weaknesses of several electric motor and transmission combinations designed to meet the specific operational demands of the tractor. As the driveline has to provide substantial torque while maintaining optimal operating conditions and avoiding overheating, a series of experiments were conducted, covering various electric motor configurations operating within the 60V range, with power outputs ranging from 1000 to 1500 watts and including multiple gearbox variations. A comparative analysis was performed to assess the advantages and disadvantages of direct chain drive transmission solutions without a differential on a rigid axle, in contrast to a sealed motor-gearbox unit featuring differential and semi-axles. The results of this research were used for mathematical comparison of the driveline solutions, enabling the detection of optimally matched transmission and motor solutions. The experiments also covered the identification of energy-efficient solutions and optimal design parameters for an electric tractor explicitly designed for continuous operation exceeding 10 hours, with cargo capacity exceeding 500 kg, high off-road maneuverability, and a service life exceeding 5000 hours. The dynamic tests carried out during the research have provided valuable insight into the relation of the overall power efficiency of the vehicle to the weight and transmission ratio variations.

A rigid-axle-based molecular rotaxane channel facilitates K+/Cl- co-transport across a lipid membrane.

Inspired by the design criteria of heteroditopic receptors for ion-pair binding, we herein describe a new strategy to construct a rotaxane transporter (RR[2]) for K+/Cl- co-transport. The use of a rigid axle improves the transport activity with an EC50 value of 0.58 μM, presenting a significant step toward developing rotaxane artificial channels.

Set-Based Design Method for Rigid Axle Suspension using Bayesian Active Learning

Set-Based Design Method for Rigid Axle Suspension using Bayesian Active Learning

Numerical Determination of the Accuracy of Gravity Center Coordinates and Stability of a Model Concept of Harvester with the Rigid Frame

The paper deals with the verification of the stability of a new design concept of a hybrid harvester intended for thinning and with the determination of deviation between two methods of measuring the machine’s center of gravity, i.e., between the methods of determining the center of gravity using the SolidWorks software made by Dassault Systems and using portable vehicle scales with the function of gravity center calculation. The machine was measured in five different positions from going up or down the slope or driving along the contour line. The new prototype of a harvester with a non-conventional rigid frame and both axles steered was found to be unstable at the maximum reach of hydraulic boom if it is situated at a right angle (±90°) to the machine longitudinal axis. A comparison of the two methods of determining the center of gravity resulted in a total deviation of 8.41%, with the deviation for x being on average 14.36% and for y only 3.08%.

Simulation of a vehicle movement on a roadway with stochastic irregularities prescribed by the power spectral density

A vehicle represents a mechanical system, which consists of bodies interconnected by joints, force elements, constraints and other coupling elements. When a vehicle moves on a roadway, it is excited due to roadway surface irregularities. It results to vibration of the vehicle mainly in the vertical direction. These vertical movements are known as a vertical dynamics of vehicles. The level of vibrations characterized by their frequency and amplitudes considerably effects two main phenomena, i.e. driving safety and ride comfort for passengers. Therefore, it is necessary to investigate and analyse response of vehicles to the vertical excitations. This article is aimed at evaluation and research of driving properties of a vehicle by means of simulation computations. In case of analysing vehicle’s mechanical system using a virtual model, it is necessary to define in a proper way not only parameters of an investigated vehicle, but also parameters of the excitations due to a roadway surface irregularities. In the reality, roadway surface irregularities have a stochastic behaviour. These fact is processed using statistical methods and it results to the power spectral density of the roadway surface irregularities. A presented research is focused on evaluation of selected output quantities of a vehicle, which moves on the road at various speeds and on various road qualities. An evaluated vehicle uses independent front wheels suspension, which design comes from the utility model. The rear axle is a rigid axle. Dynamic analyses and assessment of the resulting parameters were performed in the Simpack multibody software package. Based on reached results it is obvious, that vertical dynamics of the vehicle is affected by road quality and driving speed. Moreover, the performed analyses have proven, that the used independent front wheels suspension improves driving properties of the vehicle, contributes to better ride comfort and ensures required driving safety.

Model reference adaptive LQT control for anti-jerk utilizing tire-road interaction characteristics

Sudden vehicle propulsion torque change under tip-in/out maneuver often leads to low-frequency longitudinal vibration due to the flexibility in the half-shaft and tire slip, which greatly affects vehicle drivability. Note that the vibration frequency is between 1 and 10 Hz and is difficult to be absorbed by the vehicle mechanical system. To optimize the vehicle drivability under tip-in maneuver, an Adaptive Linear Quadratic Tracking (ALQT) anti-jerk traction controller is proposed in this paper. Based on the experimental data, a Carsim-Simulink co-simulation model is developed for assessing control performance. A control-oriented model, considering the nonlinear characteristics of the tire-road friction coefficient and slip ratio, is then proposed. A reference model with rigid axle is used to provide the equilibrium points and reference velocity trajectory. Jacobi linearization method is then used to linearize the model along the desired trajectory and a linear deviation model based on equilibrium points is obtained. Finally, the deviation compensation receding horizon LQT controller is designed along with the Kalman state estimation. The effectiveness of the designed controller is assessed via simulation studies under different road surfaces and compared with PID and LQR controllers. The LQT controller is able to track the desired velocity profile with minimum jerk while increasing road safety. Furthermore, the effect of LQT weighting coefficients under different road surfaces are discussed. Simulation results show that the ALQT controller is able to optimize vehicle drivability under different road surfaces and the weighting matrices shall be selected based on the road condition for optimal drivability.

Modelling the dynamics of an unconventional rail vehicle bogie with independently rotating wheels with the use of Boltzmann-Hamel equations

ABSTRACT The development of new technologies in public passenger transport in urban agglomerations has forced the institutions responsible for organising such transport to engage in unconventional initiatives in order to improve it and make more available, especially for elderly and disabled people. One of such initiatives consists in striving for putting into operation an increasing number of tram vehicles featuring low floors allowing people with various dysfunctions to move freely inside it and significantly facilitating entering and leaving the tram at stops. The design of such vehicles excludes the use of traditional chassis solutions since it is impossible to use wheelsets in which the wheels are connected by a rigid axle. Simulation analyses of such wheelsets come down to creating mathematical models featuring non-holonomic constraints in their description, whereas this prevents using classical equations of technical mechanics, such as Newton's equations in the construction of such models. The article describes the process of building a physical and mathematical model of an unconventional bogie with fully independent wheels with the use of Boltzmann-Hamel equations as well as exemplary results of simulation analyses of a model of such system. A design solution for this type of bogie will also be discussed.

Experimental study of the coefficient of rolling friction of the axle of a Maxwell's wheel on a soft horizontal surface

We have studied the rolling motion of a specially designed Maxwell’s wheel. The rigid axle of the wheel rolls on a pair of horizontal tracks. The central disc of the wheel rotates in the air symmetrically betweeen the tracks. Soft nitrile foam sheets have been pasted on the metallic tracks. We attach a pair of identical metal sleeves on the axle on two sides which allows us to change the effective rolling diameter of the axle. By this arrangement we can change the ratio of the rotational energy of the wheel over its translational energy. The soft surface undergoes deformation as a result of which the surface reaction force acts at a point on the axle slightly in front of the ideal contact point between the two. This offset distance has been related to the deceleration of the wheel as well as its loss of energy. From the deceleration we determine the offset distance. The coefficient of rolling friction determined from the offset distance shows a power law dependence on the dimensionless energy ratio.

Light Triggers Molecular Shuttling in Rotaxanes

In this work on rotaxanes comprising a strapped-porphyrin as a ring molecule and a dumbbell bearing one fullerene stopper, coordination forces are crucial for the excited state behavior. Distinct differences in the lifetime of the charge-separated state and the presence of more than a single lifetime were observed. Here, the coordinating properties and the polarity of the solvent have the strongest impact. For example, in apolar, non-coordinating toluene, a single lifetime was found for the charge-separated state, whereas in polar, coordinating PhCN, a short-lived and a long-lived charge-separated state evolved. In toluene and PhCl, these effects were also induced when a coordinating species, such as pyridine, was added. Depending on the solvent polarity, the shuttling is either directional or random. In apolar toluene and in the presence of pyridine, Coulombic interactions in the ZnP•+-C60 •-radical ion pair dominate and, in turn, force a close proximity between the oxidized porphyrin and the reduced fullerene. This sets up the means for a directional molecular shuttling, which results in a drastically reduced lifetime of the charge-separated state. In highly polar benzonitrile, shuttling is random and allows the fullerene anion to move further away from the porphyrin cation. This enables the system to overcome the barrier of Coulombic attractions. As such, larger porphyrin-to-fullerene distances go hand-in-hand with a longer lifetime of the charge-separated state in a high-polarity coordinating solvent; longer relative to that in either non-coordinating solvents or low-polarity solvents. Independent confirmation for our hypothesis came from the absence of a longer and/or a shorter-lived charge-separated state in the presence of a coordinating solvent in analogous experiments with a system, which features a strapped free-base porphyrin rather than a zinc porphyrin. Our results emphasize the importance of coordination interactions. To gain further insight, rotaxanes with longer, more rigid axles, which should enhance the effects on the distribution of lifetimes, are currently being designed and studied in our laboratories. Finally, a porphyrin with a metal center that binds pyridine more strongly than zinc, such as ruthenium, could exhibit interesting behavior.

Study and Simulation of a Hydropneumatic Suspension for Telescopic Handler Vehicles

The article shows the study and simulation of a hydropneumatic suspension to be adopted for a telescopic handler vehicle. The hydropneumatic suspension system with independent wheels and with quadrilateral architecture has been studied to improve the comfort and the productivity of the existing vehicle, which has a suspended rigid axle on the front and a rigid axle on the rear, which limits the comfort and the grip. After the choice of the architecture and the kind of suspension, the article shows the design of the suspension kinematics. The optimization of the characteristic angle of the suspension has been performed by means of Adams/Car and Adams/Insight. The kinematic model optimized is subsequently reproduced in Adams/View to simulate the dynamics of the complete vehicle. The simulation results are used to evaluate the vehicle performances in terms of comfort and stability according to the methods proposed by the standards.

Dynamic of Friction Coupling Independently Rotating Wheels for High Speed

A new lateral coupling structure with independently rotating wheels (IRW) is proposed, and longitudinal creepage is obtained by replacing the gear pair with the friction pair to synchronize the rotation speed of left and right wheels. The auxiliary wheelset made up of two friction wheels can be placed either under the primary suspension or on the frame. Vehicles dynamics models with three different kinds of bogies are developed, including friction coupling bogie with independently rotating wheels (FCIRW-bogie), bogie with independently rotating wheels (IRW-bogie), and bogie with rigid wheelsets, and their guiding and resetting capability when negotiating large-radius curves are compared and analyzed. Results show that FCIRW has the advantages of both IRW and rigid wheelset. On the straight track, FCIRW has sufficient wheel-rail longitudinal creep force to assist the reset; its critical speed is much higher than that of the rigid wheelset. On the curved track, the whole vehicle wear power of FCIRW-bogie vehicle is about 2/3 of the rigid axle level.

Influence of axle length on the rate and mechanism of shuttling in rigid H-shaped [2]rotaxanes.

A series of [2]rotaxane molecular shuttles was prepared containing a dibenzo[24]crown-8 (DB24C8) wheel and a rigid H-shaped axle with varying track lengths between recognition sites; from 7.4 to 20.3 Å as defined by 1-4 phenyl rings or a naphthyl group. The rate of shuttling was measured by variable temperature 1H NMR spectroscopy for neutral compounds and EXSY experiments for dicationic species. The rates were found to be independent of the length of the axle, except when the distance between the two recognition sites might be short enough (n = 1) to allow the crown ether to simultaneously interact with both recognition sites providing a short-cut mechanism which could lower the energy barrier. This notion is supported by DFT calculations and solid-state characterization of model compounds that mimic possible transition states.

Rational Design for Rotaxane Synthesis through Intramolecular Slippage: Control of Activation Energy by Rigid Axle Length.

We describe a new concept for rotaxane synthesis through intramolecular slippage using π-conjugated molecules as rigid axles linked with organic soluble and flexible permethylated α-cyclodextrins (PM α-CDs) as macrocycles. Through hydrophilic-hydrophobic interactions and flipping of PM α-CDs, successful quantitative conversion into rotaxanes was achieved without covalent bond formation. The rotaxanes had high activation barrier for their de-threading, so that they were kinetically isolated and derivatized even under conditions unfavorable for maintaining the rotaxane structures. (1) H NMR spectroscopy experiments clearly revealed that the restricted motion of the linked macrocycle with the rigid axle made it possible to control the kinetic stability by adjusting the length of the rigid axle in the precursor structure rather than the steric bulkiness of the stopper unit.

Design Approach for the Vehicle's Steering Linkage Fitted on Rigid Axle

The steering system of a vehicle consists of two subsystems: the steering linkage, which correlates the steering angles of all the steerable road-wheels, and the actuation subsystem, which connects the driver's steering-wheel with one mobile element of the steering linkage. In the case of the vehicles with rigid steering axles, the most used steering linkage is a simple mechanism, composed of four bars (one being the base) connected with four joints. However, the design of the steering linkage isn't an easy task, mainly because the wanted correlation function is difficult to specify and because the packaging restrictions are very important. The present paper shows a possible approach to define the optimization function and the dimensions of the correlation steering mechanism.

A molecular shuttle that operates inside a metal-organic framework.

A 'molecular shuttle' is an interlocked molecular assembly in which a macrocyclic ring is able to move back and forth between two recognition sites. This large-amplitude translational motion was first characterized in solution in 1991. Since that report, many mechanically interlocked molecules (MIMs) have been designed, synthesized and shown to mimic the complex functions of macroscopic switches and machines. Here, we show that this fundamental concept-the translational motion of a molecular shuttle-can be organized, initiated and made to operate inside a crystalline, solid-state material. A metal-organic framework (MOF) designated UWDM-4 was prepared that contains a rigid linker that is a molecular shuttle. It was demonstrated by variable-temperature (1)H-(13)C cross-polarization/magic-angle spinning (CP/MAS) and (13)C 2D exchange correlation spectroscopy (EXSY) solid-state NMR at 21.1 T on a (13)C-enriched sample that the macrocyclic ring undergoes rapid shuttling along the rigid axle built between struts of the framework.

후륜 구동 차량의 급가속 시 구동계 진동 저감

A torsional vibration at driveline happens seriously at rapid vehicle acceleration. The torsional vibration at driveline can be reduced by optimization of joint angle and yoke phase angle of driveline. But, the joint angle of driveline is changed according to vehicle driving condition as acceleration, deceleration, forward and backward driving, so that excessive vibration is transmitted to vehicle body at specific driving condition. Especially under rapid acceleration condition, vibration transmitted to body could be maximized because excitation force at rapid acceleration is bigger than that at normal driving condition due to changed joint angle. The torsional vibration of driveline can be kept at low level by controlling suspension parameter to minimize rigid axle displacement as well as optimizing joint angles considering the vehicle acceleration condition.

A 2,2′-bis(benzimidazolium)-dibenzo[24]crown[8] rigid pseudorotaxane system

Pseudorotaxanes from the self-assembly of simple 2,2′-bis(benzimidazolium) dications and DB24C8 is a first of its kind when a protonated bis(benzimidazole) without a methylene spacer between the two benzimidazolium units (a very rigid axle without flexibility) thread DB24C8 as a result of H-bonding interactions. The formation of these pseudorotaxanes was first ascertained from 1H NMR spectroscopy and later corroborated by HRMS, 2D NMR and finally supported by rigorous DFT calculations.

Increased Halide Recognition Strength by Enhanced Intercomponent Preorganisation in Triazolium Containing [2]Rotaxanes

Three triazolium-based [2]rotaxanes containing different sized axle and macrocycle components were synthesised in good yields (40-57%) through chloride anion templation. The anion recognition properties of the interlocked receptor systems were investigated using (1)H NMR titration experiments: all three rotaxanes display impressive selectivities for halide anions over the more basic oxoanion acetate. The rotaxanes incorporating shorter, more rigid axle components with aryl-substituted triazolium groups display substantially higher anion binding affinities than those with longer, bis-alkyl-substituted heterocycles, which is attributed to the increased intercomponent preorganisation afforded by the smaller axle component. Computational DFT and molecular dynamics simulations composed of unconstrained and umbrella sampling simulations corroborate the experimental observations.

Kinematic and dynamic analysis of a heavy truck with individual front suspension

The main focus of this work is on the characteristics of a commercial vehicle with individual front suspension (IFS). Both kinematic and dynamic properties of the vehicle are investigated through simulations and analytical expressions. Moreover, employing the model of the tractor semitrailer combination, the study presents the results of comparison between the trucks with IFS and rigid front axle with respect to comfort and handling. This is done by analysing the responses of the vehicles to different road and steering inputs. The obtained results show enhanced comfort and steering feeling for the truck with IFS.

A Flexible Copper(I)‐Complexed [4]Rotaxane Containing Two Face‐to‐Face Porphyrinic Plates that Behaves as a Distensible Receptor

A new cyclic [4]rotaxane composed of two flexible bis-macrocycles and two rigid axles is described. Each bis-macrocycle consists of two rings attached to antipodal meso positions of a central Zn porphyrin through single C-C bonds. Each ring incorporates a 2,9-diphenyl-1,10-phenanthroline chelation site. The axles contain two coplanar bidentate sites derived from the 2,2'-bipyridine motif. The building blocks were assembled by using a one-pot threading-and-stoppering reaction, which afforded the [4]rotaxane in 50% yield. The "gathering-and-threading" effect of copper(I) was utilised in the formation of a [4]pseudorotaxane, which was immediately converted to the corresponding [4]rotaxane by a quadruple CuAAC stoppering reaction. The rotaxane contains two face-to-face zinc porphyrins, which allowed the coordination of ditopic guest substrates. The rotaxane host showed remarkable flexibility and was able to adjust its conformation to the guest size. It can be distended and accommodate rod-like guests of 2.6 to 15.8 Å in length.