Types, Functions, And Operation Of Heavy Commercial Vehicle Steering And Suspension Systems

Environmental requirements for fluid disposal in steering and suspension systems

Q1. Explain the environmental requirements, including procedures for trapping, storing and disposing of fluids released from steering and suspension systems?

Ans 1. The fluids used in steering and suspension system needs to be disposed or recycled through trapping, storing and disposing techniques. The fluid needs to be locked and prevented from leaking. It should not be allowed to be mixed with any other chemical or fluid and stored in original containers. The ignition sources should be kept away from such fluids and other chemicals should be avoided. Disposal of the fluids needs to be done using fuel-soaked rags, used material for oil-spills, fuel line antifreeze, windshield fluids, antifreeze, battery acids, fluids and deicers, vehicle touch up paint, used oil and oily fluids (Jagtap, 2016). These fluids are harmful to the environment due to their toxicity, flammability, corrosivity and reactivity.

Q2. Name the types of complex faults relating to heavy commercial vehicle steering and suspension systems, including:?

Intermittent

Multi-system

Introduced as a result of system repair

Indirect, caused by the influence of external systems

Ans 2. A suspension system that is multi link usually is the suspension design for independent suspensions that is used for lateral arms as well as longitudinal arms. The arms are usually not of equal length and are angled away towards an obvious direction. The arms have spherical joint or rubber bushing at either ends. According to Jamali (2014), the vehicle suspension is used for the reduction of effect of the vibrations generated by the irregularities of road. The active suspension is able to add both the dissipated energy from system that results in capability of controlling vehicle attitude reducing the braking and rolling during maneuvers to increase rider comfort as well as handling.

Q3. Name the function and operation of heavy commercial vehicle steering and suspension systems, including:?

Manual steering systems

Power assisted steering systems, including:

Power steering pumps

Power steering boxes

Rack and pinion steering

Electronic and load sensing steering systems

Leaf spring suspension

Equalizer beam-leaf spring and solid rubber spring suspension

Rubber block and torsion bar suspension

Air spring suspension, including:

Pneumatic

Combination pneumatic and leaf spring

Axle alignment

Ans 3. Adjustment nuts and plugs are usually provided for adjustment of endplay of the worm gear. Different types of manual steering systems are present such as worm and sector, worm and rotter, cam and lever, worm and nut, rack and pinion systems. Larger and heavier engines have a trend of having tires that have increased requirements of steering effort (Johnson, 2013).

Electro hydraulic power steering systems are also known as hybrid system due to the hydraulic pressure that comes from the pump driven through an electric motor instead of a conventional electric motor that is driven by a belt at engine. Kiselis (2015) stated that the hydraulic power steering system augments the steering effort with help of an actuator along with a hydraulic cylinder that usually forms a part of a servo system.

The hydraulic pressure in the electro hydraulic power steering systems comes from the rotary vane pump that is usually driven by the engine of the vehicle. The valves for controlling flow to the cylinder operate the steering wheels. The hydraulic power steering pumps are usually positive displacement type and the flow rate delivered by them is usually directly proportional to the engine speed.

Power steering box is also known as the gear box that helps in translating the wheel movement of the steering into front wheels movement. High performance vehicles are categorized as vehicles having low ratio of steering that is even lesser input into steering wheels has a large effect on output of the wheel. With either of the system, pump’s fluid pressure flows from one side to another side as the piston moves (Koulocheris, 2016). The piston is usually attached to the gears of the steering. Hydraulic pressure usually performs the work that enables the driver in controlling the direction of steering wheel by turning it.

Complex faults in steering and suspension systems of heavy commercial vehicles

Rack and pinion steering is usually a linear actuator that is generally comprised of gear pairs that helps in to rotational motion to linear motion. The circular gear also known as the pinion helps in engaging the teeth on a gear bar that is linear also known as the rack. The rotational motion that is applied to the pinion causes the rack in moving relative to the pinion thus helping to translate the rotational motion into linear motion.

According to Li (2014), electronic and load sensing steering system ensures that the flow and pressure is usually adjusted according to the actual demand. The adjustment helps in increasing the efficiency of the hydraulic system as well as reduces the emission increasing the lifetime of system.

Leaf spring suspension is usually the simple spring that is commonly used for the overall suspension in heavy vehicles. They are also known as the carriage and laminated springs and is referred to as semi-elliptical spring or casted spring and is one of the oldest springing forms.

Equalizer beam-leaf spring is usually steel lead springs that is connected through balance beam for equalization of the loads. The spring helps in improved equalization of axles on the semi-trailer. Solid rubber spring suspension helps in absorption of the impact efficiently compared to a solid rubber bump stop.

Hilton (2013) stated that one end of the long metal bar is usually attached firmly to the chassis of the vehicle and the opposite end is terminated into a lever. The torsion key is usually mounted perpendicular to the bar and is attached to the arm of suspension, a spindle or the axle.

Air suspension is the vehicle suspension that is provided and is usually powered with the help of an electric or engine driven compressor or air pump. The compressor helps in pumping the air into bellows that is flexible. The air pressure helps in inflation of the bellows and rubber made from textile reinforcement. The chassis is raised from the axle in the process.

Pneumatic suspension is usually the type of motor vehicle suspension system in which torque multiplication is used as well as pneumatic systems based on the compressibility of gas to protect the equipment from accidental shock or damage. The gas absorbs excessive force and the fluid helps in transfer of force directly.

Leaf spring combined with pneumatic suspension helps in transferring loads as well as shocks from the leaf spring towards the lever. Further, the end of the spring has a shock and load-transmitting lever.  

Functions and operation of various steering and suspension systems

The axle alignment helps in correction of the adjustable hanger bracket for exhausting the air from suspension of trailer (Javanshir, 2014).  

Q4. What are the testing procedures for heavy commercial vehicle steering and suspension systems, including procedure for:?

Vehicle dynamic and static testing, including hydraulic tests of power assisted steering systems component inspection

Abnormal noise analysis

Component failure analysis

Ans 4. Vehicle static testing is usually performed within laboratories that involve the vehicle parameter measurement like height of center of gravity as well as track width (Zhu, 2014). These parameters are combined with yield static metrics that is related to static stability factor (SSF). The static tests for entire vehicles like tilt table and side pull test that is performed for data correlated to the vehicle rollover propensity. Further dynamic testing is executed on track test that involves driving maneuvers, is usually potentially helpful in understanding events immediately for preceding rollovers, is quite expensive, and requires precautions of safety for test drivers. As per Nieto (2016), abnormal noise analysis is evaluated using Dytran three-phase accelerometer, DASP test analysis software, notebook computers are also used for the analysis. Hammer excitation is usually achieved through force hammer structure of percussion of the force sensor as well as excitation generated through signal through pact hammer. The device modal test usually uses system of free bearing as well as excitation of single point pickup method of response measurement.

The automotive industry faces new challenges that are demanded as inexpensive as well as high quality increase of components. Extreme diligence is imparted that ensures components are manufactured and designed through sufficient quality with various service environments (Ramsey, 2015). During component failure, root cause of the failure is usually quickly determined with high accuracy and proper corrective measure is taken for preventing the future failures. Systematic analysis is usually conducted for finding the failure’s root cause.           

Q5. Types, functions, operation and limitations of diagnostic testing equipment required to diagnose complex faults in heavy commercial vehicle steering and suspension systems.

Ans 5. The types, functions, operation and limitations of diagnostic testing equipments required for diagnosis of faults that are complex in heavy commercial vehicle steering and suspension systems have been described. Shafie (2015) stated that the different types of diagnostic testing equipments required for diagnosing complex faults in heavy commercial vehicle steering and suspension systems are Multimeter, Vacuum-pressure gauge and fuel- pressure gauge. Xie (2015) commented that multimeter is used for checking the output voltage of the vehicle. Vacuum-pressure gauge is used for tracking cracked tubes and fuel-pressure gauge is used for checking the fuel pressure on engine. Sensors on car usually convert temperature as well as other readings in voltage that is only understood by the computer of heavy commercial vehicles. Advanced computer systems installed within the vehicle helps in checking output sensor voltage for verification of any kind of faulty wiring and creating bad part out of spec signals, which can cause trouble for the vehicle. During poor performance of car engine due to spark, fuel or air, vacuum pressure gauge is used for covering the air department for working through the maze of lines of vacuum under hood for tracking down cracked tube, which can be throwing things off (Samin, 2015). Fuel pressure gauge is used for checking the fuel pressure within carbureted engine however, modern system of fuel injection usually requires dedicated fuel pressure gauge. Fuel is the major step in troubleshooting for heavy automotive engines. Once the complex faults within the heavy commercial vehicles are detected, confirmed and tested. Few of the alternative default signal values are usually used by the ECU within ‘limp-home’ mode in which the vehicle can be driven towards nearest service centre (Sun, 2015). Diagnostic processor helps in providing warning drivers for logging DTCs as well as additional environment parameters like timestamp and temperature that is noted for no actual processors in deployment. 

Diagnostic testing equipment required to diagnose complex faults in these systems

References

Jagtap, K., Rathod, Y., Shedge, A., Gramopadhye, M., & Diware, V. (2016). SUSPENSION SYSTEM FOR AN ALL-TERRAIN VEHICLE: A REVIEW. International Journal of Engineering Research and General Science, 4(3), 14-25.

Jamali, A., Shams, H., & Fasihozaman, M. (2014). Pareto multi-objective optimum design of vehicle-suspension system under random road excitations. Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics, 228(3), 282-293.

Johnson, M., Molitor, M., Galla, J. M., Klein, J., Roe, D., & Dykstra, D. R. (2013). U.S. Patent No. 8,371,596. Washington, DC: U.S. Patent and Trademark Office.

Kiselis, G. P., & Brown, M. A. (2015). U.S. Patent No. 9,010,782. Washington, DC: U.S. Patent and Trademark Office.

Koulocheris, D. V., Papaioannou, G. D., & Christodoulou, D. (2016). Assessment of the optimization procedure for the nonlinear suspension system of a heavy vehicle. Mobility and Vehicle Mechanics, 42, 17-35.

Li, H., Jing, X., Lam, H. K., & Shi, P. (2014). Fuzzy sampled-data control for uncertain vehicle suspension systems. IEEE Transactions on Cybernetics, 44(7), 1111-1126.

Li, H., Yu, J., Hilton, C., & Liu, H. (2013). Adaptive sliding-mode control for nonlinear active suspension vehicle systems using T–S fuzzy approach. IEEE Transactions on Industrial Electronics, 60(8), 3328-3338.

Mahmoodi-Kaleibar, M., Javanshir, I., Asadi, K., Afkar, A., & Paykani, A. (2013). Optimization of suspension system of off-road vehicle for vehicle performance improvement. Journal of Central South University, 20(4), 902-910.

Nieto, A. J., Morales, A. L., Chicharro, J. M., & Pintado, P. (2016). An adaptive pneumatic suspension system for improving ride comfort and handling. Journal of Vibration and Control, 22(6), 1492-1503.

Ramsey, J. E. (2015). U.S. Patent No. 9,150,072. Washington, DC: U.S. Patent and Trademark Office.

Shafie, A. A., Bello, M. M., & Khan, R. M. (2015). Active vehicle suspension control using electro hydraulic actuator on rough road terrain. Journal of Advanced Research, 9(1), 15-30.

Sulaiman, S., Samin, P. M., Jamaluddin, H., Rahman, R. A., & Bakar, S. A. A. (2015). Tyre force control strategy for semi-active magnetorheological damper suspension system for light-heavy duty truck. International Journal of Vehicle Autonomous Systems, 13(1), 65-90.

Sun, S. S., Yang, J., Deng, H. X., Du, H., Li, W. H., Alici, G., & Nakano, M. (2015). Horizontal vibration reduction of a seat suspension using negative changing stiffness magnetorheological elastomer isolators. International Journal of Vehicle Design, 68(1-3), 104-118.

Xie, Z., Wong, P. K., Zhao, J., & Xu, T. (2015). 1561. Design of a denoising hybrid fuzzy-pid controller for active suspension systems of heavy vehicles based on model adaptive wheelbase preview strategy. Journal of Vibroengineering, 17(2), 12-23.

Zhu, Y., Wang, Y., & Huang, Y. (2014). Failure analysis of a helical compression spring for a heavy vehicle's suspension system. Case Studies in Engineering Failure Analysis, 2(2), 169-173.