Suspension Spring for an Offroad Vehicle - Report Example

Suspension Spring for an Off-Road Vehicle (Retro Fit) Student’s Name: Institutional Affiliation: Summary Many four wheelers see truck suspension as an instrument of set what they strongly need in tire size under their track. These people only concentrate on the lift but not functions. On the other hand, engineers have much more to consider. What we should understand is that packaging is a critical factor. Engineers will consider the shocks, tire size, suspension travel needed as well as the CV joints working limits, spherical bearings and other hardware[Els07]. The laws of physics dictate the results of the final design once the limits of the hard parts being used have been factored in. Suspension refers to the system of tires, tire air, shock absorbers and linkages connecting a vehicle to its wheels in order to permit relative motion between the two wheels. The system serves a dual purpose of good braking for safety and driving pleasure and proper road holding and handling. The good suspension ensures quality ride and comfortability that is isolated from bumps, noise, and vibrations. Because these goals are odd, turning the suspension is all about coming up with the right compromise[Dem12]. Vehicle suspension should keep the road wheel in contact with the road surface. This is because all the forces from the ground and road surfaces acting on the vehicle are from contact patches of the tires. A good suspension will protect the cargo and the vehicle itself from unnecessary wear and damage. The rear and front suspension may be different in design[Kri13]. Table of Conten Running head: suspension spring 1 1 Summary 2 Introduction 4 Vehicle Suspension 4 Solid Axle with Coil Springs 5 Twin Traction Beam (TTB) 5 Radius Arm Setup 8 Parallel and Triangular Four Link 9 Conclusion 9 Figure 1: Caster Angle Figure 2: Tire Centerline 7 Figure 3: Radius Arm Setup 8 Figure 4: Parallel 4 Link 8 Introduction Factory springs and other aftermath springs are made from different parks in order to fit in with different factory perches. One can use two different springs as long as they are designed for the exact weight of the truck. The problem comes when the weight of the truck differs from the ideal weight of the springs, or when the springs have different spring rates. The truck leans to one side or the other because of the different spring rates of the truck. Identical springs on the right and the left side of the vehicle results to lifts that do not cause the vehicle to lean. In case you want to lift the vehicle for off-road purposes, several modifications will be required for the steering, shocks and drive shafts. The shocks will have to be replaced with longer units in the shock location, or the upper shock mount will be replaced with the long travel hooks and shocks. With lifted suspension system the drive shaft must be lengthened[Yin15]. Vehicle Suspension Vehicle suspension has three major jobs: keep tires touching the ground, maintain vehicle stability, and smooth out bumps. Springs absorbs the shock, energy and forces that act on the wheel. The most common types of springs are the coil and leaf springs. Both of them are good with energy absorption. However, shock absorbers are required to decrease and dampen the vibration after a vehicle has hit a bump. In a vehicle, every wheel has a spring and shock absorbers. The front suspension is however not the same with the rear suspension because the front wheels are made to turn right and left as it directs the vehicle. The front suspension also absorbs more braking torque. This makes the front suspension more complex than the rear suspension. The following are two reasons as to why the front suspension of off-road vehicles tends to be so complicated than the rear suspension. The terrain offers nastier bumps, and the wheels are always bigger. For a four wheel drive suspension often features a solid axle with leaf springs. This type of suspension is known as a dependent system because the wheels are literally connected so as they move together as a unit. The frame of the vehicles has leaf springs attached to it, then via U-bolts, to the axle housing[LiH14]. The body roll is controlled by a sway bolt mounted to each side of the axle. Generally, an off-road vehicle suspension includes the following: Independent front suspension system (IFS) In this type of suspension, the two front wheels move independently. In an IFS system, there is an upper and lower control arm connected to the wheel on one side. The torsion bar acting like a straightened coil spring accomplishes the springing. Springing can also be completed with coil struts, which combines shock absorbers and coil spring into a single unit[Che00]. Solid Axle with Coil Springs This is another dependent system which replaces multiple leaf spring with coil springs[Dov07]. Coil spring is preferred by many off road drivers because of their compact design. They are also preferred because they deliver a smoother and quieter ride. Twin Traction Beam (TTB) TTB is also referred to as I-beam, it is a suspension designed by Ford motors to blend the best of dependent and independent systems. A TTB system is characterized by two beams at the front of the vehicle. Each beam mounts on the pivot on one end, and on the wheel on the other. These beams overlaps a bit and they work in essence control like control arms. Independent movement in of both beams is facilitated by a U-joint[Koc14]. Most of 4 X 4 vehicles have a solid axle with leaf or coil springs on the rear. Shock absorbers are often mounted by off-road drivers on opposing sides of the axle. This is done in a way that one is in front and the other behind to reduce a rapid up and down motion of rear axle. Such notions are always cause by sudden acceleration[Paz12]. There are several ways to make your suspension keep the tires planted to the ground and hold the truck up. Factory suspension cannot be compared without mentioning caster and center. In order for the steering to be more stable and return to the center, caster angle are built into the center of front suspension. On the other hand, camber refers to the angle of the tire to the road. When the tire leans in at the top and in contrast, it is known as negative camber. Positive camber is a situation where the tire leans out of the top as illustrated by the diagrams below. Figure 1: Caster Angle Figure 2: Tire Centerline Looking at the solid axle once again, we find that it is an axle running from one side of the truck to the other. As the suspension cycles, the entire axle moves. Many manufacturers have used Solid axle/leaf spring configuration for decades because hardcore four-wheelers still cover it. This design has survived for a long time because of its ability to act as a duty leaf spring suspend to the truck and also locate the axle. This is a double duty. The leaf spring runs parallel to the frame and is attacked solidly to the axle with U-bolts. On one end the springs are attached to the solid perch, and on the other end the shackles that pivot. When the axle hits an obstacle, the leaf spring compresses; this compression makes it flatter and longer, and the axle allows the spring to move without binding. Most col springs have a linear spring rate according. On the other hand, leaf spring has a progressive spring rate because of their multi-leaf design. The spring rate arises more with compression of leaf spring, meaning, the more the leaf spring compress, the higher the spring rate rises. With their widths having been varied, their lengths, thickness and number of leaves, they can suspend anything from a small car like Suzuki Samurai to a large cement truck. Given shocks with necessary damping to control the springs in the rebound, they things work better. For this reason, they are extensively used for the rear and/or on large trucks. Smaller trucks and SUVs are more compact, and they do not have enough room for running leaf spring[LiH13]. Radius Arm Setup Coil springs are used in solid axle designs instead of leaf springs. This is because they are more compact than leaf springs but they only support the weight of the vehicle. Coils springs cannot locate the axle as the leaf springs do. It is important for the suspension members to locate the axle and at the same time allow it to move[Buc15]. Consider the radius arm design whose diagram appears below: Figure 3: Radius Arm Setup Figure 4: Parallel 4 Link The radius arm design has two arms running parallel to the frame and solidly to the axle housing. This gives room to the axle to pivot up and down. In order to the axle to be kept centered to the frame, a track bar runs from the frame to the radius arms. When the suspension cycles up and down, the caster angles changes; this is because the radius arms are fixed at the angled end. It is illustrated more by the diagram above. Dodge Motors and Ford are using this design among other Automobile manufacturers[Zuo13]. Parallel and Triangular Four Link The figure of parallel four-link is shown alongside the figure of radius arm setup above. There are kits that are being made by after-market manufacturers. These kits retrofit an existing suspension of parallel four link design. It also uses four-link design and coil spring as well as a track bar to center the axle springs. It uses upper and lower link on each side with pivots on both ends instead of radius arms with fixed amount on the axle. The links allow maintenance of the same relationship with the ground as the axle cycles up and down. However, the caster angle remains constant[Mah13]. Any time a pivot is added, a wear item is also added, and there is potentiality for deflection. As compared to the radius arms, the parallel four-link gives strength that makes better ride quality and handling. Triangulated four-link is also another four link design. Looking at the parallel four-link design, a track bar is needed to locate the axle side by side. A triangulated four-link design comes with these links mounted at great enough angles. The track bar is therefore not needed. With wider top links at the frame and narrow at the axle housing, the lower links will be mounted with angles that are opposing with greater angles. The links resist from side to side[Els13]. Conclusion The suspension of UTVs and ATVs are typically dependent systems. There are several other times of suspensions that have not been covered by this essay. Many manufacturers, however, use A-Arm suspensions on the front of the vehicles (Li, Jing, & Karimi, 2014). The upper and the lower control arms are A-shaped just as the name suggest. There is a strut positioned on the upper arm. However on the rear, there is always an independent system angled towards the rear for a smoother and safer ride. References Els07: , (Els, Theron, Uys, & Thoresson, 2007), Dem12: , (Demir, Keshin, & Cetin, 2012), Kri13: , (Krishnasamy, Jayaraj, & John, 2013), Yin15: , (Yin & Huang, 2015), LiH14: , (Li, Jing, Lam, & Shi, 2014), Che00: , (Cherry & Hicks, 2000), Dov07: , (Dove, 2007), Koc14: , (Koch & Kloiber, 2014), Paz12: , (Pazooki, Rakheja, & Cao, 2012), LiH13: , (Li, Yu, Hilton, & Liu, 2013), Buc15: , (Buckner, Schuetze, & Beno, 1999), Zuo13: , (Zuo & Zhang, 2013), Mah13: , (Mahmoodi-Keleibar, Javanshir, Asadi, Afkar, & Paykani, 2013), Els13: , (Els, et al., 2013), Read More