This is to certify that I am responsible for the work presented in this project, that the original work is my own, except as specified in the references and acknowledgments, and that the original work contained herein was not undertaken or done by unspecified sources or persons . PTO and telescopic drive shaft systems are used to transmit power from the engine to the outboard machinery. The PTO system used by the Light Fire Rescue Tender (LFRT) manufactured by CME Technologies Sdn Bhd is not the best because it is mounted by three telescopic drive shafts instead of one.
The goal of this project is to simulate and analyze the PTO and telescopic drive shafts on Light Fire Rescue Tender trucks to identify areas for improvement. Subsequently, this project also tries to propose a new design to improve the performance of this system. To achieve the objectives, simulation and analysis of the existing system will be carried out and a recommendation of a new system will be proposed which will improve the performance of the system.
It is hoped that the Design and Development Department of CME Technologies Sdn Bhd will refer to this research after the completion of the project. Zainal Ambri Abdul Karim: the supervisor, for his never-ending assistance and supervision till the completion of the project.
INTRODUCTION
- Problem Statement
- Significance of Study
- Objectives
- Scope of Study
The PTO shaft on LFRT is located on the side of the engine transmission case and the pump is located on the rear of the chassis. The pump was connected to the PTO shaft via an assembly of three telescopic drive shafts instead of one. This arrangement ensures that the angular movement of the drive shafts causes higher friction than if they were connected straight.
The findings of the project would be offered as an option to the Design and Development Department (DDD) of CME Technologies Sdn Bhd in their design implementation for future projects and optimization of water pump operations. The aim of the project is to propose a new design that will provide greater efficiency and performance, but still within the design and space constraints of the LFRT specifications. Simulate and analyze the power transfer from the prime mover to the pump of the existing system.
To design and simulate an improved system with higher PTO efficiency and performance. In the first semester, efforts focused on literature review, data collection, simulation and analysis of the existing system.
LITERATURE REVIEW
Introduction to shaft
- Theory of Designing Shaft . 6
Most shafts are subjected to fluctuating loads of combined bending and torsion with varying degrees of stress concentration. Many shafts are not subjected to shock or impact loads; however, some applications arise where such a load occurs. In the design of round slender shafts that transmit power at a certain speed, the material and cross-sectional dimensions are selected so that they do not exceed the permissible shear stress or the limit angle of rotation.
The equation below can be used to convert the power delivered to the shaft into a constant torque applied to it during rotation. After the torque to be transmitted is determined, the design of the circular shaft can be carried out to meet the strength requirements. A safety factor n is applied to tmax to determine the allowable voltage tall = Sys/n or tall = Sus / n.
Drive shafts as power transmission tubes are used in many applications including cooling towers, pump sets, aerospace, trucks and automobiles. In metallic shaft design, the size of the shaft cross-section can be determined by knowing the torque and allowable shear stress of the material. Composite drive shafts have solved many automotive and industrial problems accompanying the use of conventional metal ones, because performance is limited due to lower critical speed, weight, fatigue and vibration.
When the length of the steel drive shaft exceeds 1500 mm, it is made in two parts to increase the fundamental natural frequency, which is inversely proportional to the square of the length and proportional to the square root of the specific modulus.” (Badie, 2006). Effective composite driveshaft design can be achieved by selecting appropriate variables that can be identified for a fail-safe structure and to meet performance requirements. Since the length and outer radius of drive shafts in automotive applications are limited by clearance, design variables include inner radius, ply thickness, number of plies, fiber orientation angles, and ply stacking sequence.
In optimal drive shaft design, these variables are limited by the lateral natural frequency, torsional vibration, torsional strength and torsional buckling.
Material Selection
- Steel properties
- Composite properties
The nature of composites with their higher specific modulus (modulus to density), which in carbon/epoxy exceeds four times that of aluminum, makes it possible to replace the two-piece metal shaft with a composite in one piece, which resonates at higher speed and thus maintains a higher margin of safety. A composite driveshaft provides excellent vibration damping, cabin comfort, reduced wear on driveline components and increased traction. Polymer matrix composites such as carbon/epoxy or glass/epoxy provide better fatigue properties, as microcracks in the resin do not grow further like metals, but end at the holes of the fibers.
In general, composites are less susceptible to the effects of stress concentrations, such as those caused by notches and holes, than metals.
Torsional Analysis
METHODOLOGY
Model
Analysis
The models were meshed to the desired length and faces of the models that wanted to be analyzed were selected. Then the torque was applied at a selected point and the software simulated deformation, Von Mises Stress and displacement of the models.
Data Collection
The resulting torque estimate will be used in the analysis to simulate the effect on the shaft. This moment value will be added to the finite element analysis in CATIA software to see the Von Mises stress evolution. The shaft end is attached to one or both ends of the shaft depending on its location.
The telescopic part is the part where the total length of the shaft can be changed according to the equipment and the length of the chassis. The front and rear do not need to be attached because the front shaft is connected to the PTO and the rear to the pump. The telescopic one will be connected to the PTO shaft, and the universal joint will be connected to the intermediate drive shafts.
This center drive shaft will connect the front and rear drive shaft and the mounting parts will be mounted on the chassis. The telescope will be connected to the pump and the cross coupling will be connected to the center drive shafts. The torque is applied to each of the 3 axes to observe the outcome of the analysis.
From Figure 4.14 and Figure 4.15 above, it can be seen that the critical part in the shaft is the telescopic part and the universal joint, but it is shown that none of the above parts experience the plastic deformation. The value is relevant for all drive shaft components of the existing model. Figure 4.17 above shows that when installing the center shafts, the shaft tends to rotate out of the bearing ring.
So the inner diameter for new axles will be 49mm and the outer diameter will be 61.2mm. For the model, the diameter is reduced to the new dimension as calculated, but the length remains the same as before. From both calculations, it shows that the new system design is optimized in relation to 3 data, which are weight reduction, Von Misses Stress reduction and observation of the drive shafts, which can contribute to improving the existing system.
When comparing the existing and new system, the power-to-weight ratio has increased by 65% as the axle weight has been reduced from 50.931 kg to 30.713 kg. It is recommended that this research be continued using more variables such as materials, thickness ratio and safety factor to observe the outcome. Automotive Composite Drive Shafts: Investigating the Effects of Design Variables”, International Journal of Engineering and Technology, Vol.
Griffin, 1998, “Computer-Aided Design Programs for Torsional Analysis” Master's Thesis, Virginia Polytechnic Institute Faculty and State University.
Gantt Chart
Research Flow
![Figure 2.1: Major components of PTO system [4]](https://thumb-ap.123doks.com/thumbv2/azpdforg/10268459.0/13.892.253.708.724.899/figure-2-1-major-components-pto-4.webp)
