What is Suspension: Definition and 130 Discussions

Suspension is the system of tires, tire air, springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both road holding/handling and ride quality, which are at odds with each other. The tuning of suspensions involves finding the right compromise. It is important for the suspension to keep the road wheel in contact with the road surface as much as possible, because all the road or ground forces acting on the vehicle do so through the contact patches of the tires. The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of a car may be different.

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  1. B

    Maximize Performance: Benefits of Moving Rear Suspension Mounting Points Forward

    Hi , most rear suspension 4 link brackets mounted on the rear end housing are centered or slightly forward of the rear axle centerline . Why ? And what are the effects of moving the mounting points forward 2”,3”,4” forward ? Thanks for the help .
  2. S

    Automotive Calculation of the reduced stiffness of a simple suspension

    Hello, I have a problem with reducing a stiffness of a front suspension. Unfortunately I don't understand how to get the reduced stiffness on the right side in the picture. (k_f=k/cos^2E) Thanks in advance for your help. Many greetings, Semat10
  3. shivajikobardan

    Engineering Dynamic physical model - automobile wheel suspension confusion

    Been a long time I studied physics that had anything to do with mechanics, so I'm now in need of memorizing almost everything. So I am seeking for some guidance here. This is "system simulation/modeling/discrete event system simulation/etc" type of subject. The first thing that I didn't...
  4. Lord Doppler

    Engineering Solving Car Suspension Modeling: Understanding Input Forces and Movement Types

    Hello, I'm trying to solve this problem but I'm confused with some things, is correct that in the system there are two input forces, the torque and u(t)? I assumed that the system has two free levels, which are the z displacement and theta (rotational movement), so the system has a linear...
  5. A

    Differential Equations and Damper Curves

    Good evening, I have been wrestling with the following and thought I would ask for help. I am trying to come up with the equations of motion and energy stored in individual suspension components when a wheel is fired towards the car but, there is a twist! I am assuming a quarter car type...
  6. K

    I Difference between electrodynamic suspension (EDS) & quantum levitation?

    What is the difference between electrodynamic suspension (EDS) in maglev trains and quantum levitation? I'm having trouble distinguishing the difference between both.
  7. jack action

    In-wheel Suspension: A New Look

    This suspension within a wheel looks really nice (source):
  8. S

    Automotive Mechanism to drive a wheel from an internal motor allowing suspension?

    I'm brainstorming how to make an electric motorbike, making as much use of the available space as possible to allow for as many batteries to be fitted as possible. Batteries aren't relevant right now; my focus is on the final drive at the back of the bike. To maximise space, I want to fit the...
  9. S

    Why isn't the Pneumatic Tyre used for suspension?

    I've been contemplating the design of a motorcycle, and I've been reading up on the sprung & unsprung weight thing, how you want to minimise unsprung weight (IE, the part of the vehicle which moves with the road, the wheel and lower half of the suspension) to improve handling. This got me...
  10. Ash81

    Automotive Does adding accessories to the front of a vehicle affect its payload capacity?

    Please forgive me if I am wrong but I am having a bit of a debate regarding vehicle payloads and load distribution My argument is that the weight of the bullbar, lights and other forward mounted accessories on the front of a utility infront of the front axle has no interference with the weight...
  11. M

    Modeling torque on a half car model

    Imagine an half car model with the two suspension and two wheels. There is a torque applied to the rear wheels, that torque create the force between tire/asphalt that pull the car. How that torque react in the main body? I have two hypotesis: 1) It's only internal force that tend to bend the...
  12. B

    Suspension location for suspension pedestal

    For my thesis at the department of Industrial Design Engineering, I am developing a suspension pedestal. These kind of products are used regularly in boats (link) or truck seats and make use of two diagonal beams and a shock absorber. The vertical excitation can originates from waves or road...
  13. Charlie Cheap

    Rear leaf suspension modifications

    I am building a 1967 Sunbeam Alpine and installing a Ford Lima 2.3 modified 4-cylinder with an A4LD overdrive automatic. At 75 I still love to drive but this is for long trips. That sounds crazy for a car with an 89 in wheelbase, but it is what I am doing. The rear leaf suspension will be...
  14. J

    Torque about a pendulum's suspension point

    Homework Statement In the figure attached, what is the torque about the pendulum's suspension point produced by the weight of the bob, given that the mass is 40 cm to the right of the suspension point, measured horizontally, and m=0.50kg? Homework Equations tau = rFsin (theta) or tau = lF...
  15. F

    Magnetic Suspension Circuit: Troubleshooting Levitation

    I am building a magnetic suspension circuit. Basically to hold up a ball with a a piece of metal inside using a coil with an electromagnetic current. The circuit has already been set up. The ball is attracted to the coil but does not stay levitated. It should stay below the led sensor and the...
  16. Physics345

    Explaining Damping with a car's suspension

    Homework Statement Explain what is meant by damping. Choose a specific technology that requires a damping mechanism and describe how the damping takes place. Homework Equations none The Attempt at a Solution Damping is to reduce amount of friction being caused from oscillations, therefore...
  17. Tom Rauji

    Automotive Suspension interaction with car

    I need help or guidance at a physics level understanding suspension interaction with a vehicle chassis. Here is the problem. I have a very high horsepower car with small tires. The race tracks are prepped with a glue. It is very easy to go over 1500 HP with a pretty high gear ratio. For...
  18. O

    Vertical cables in a suspension bridge

    Homework Statement Problem 5 here: http://www.princeton.edu/~romalis/PHYS203/HW1.pdf Homework Equations N/A The Attempt at a Solution The part that really confuses me is where it says that the cable lengths are adjusted so there is no shear stress on the bridge. What exactly does this mean...
  19. Hareesh Venkatraan

    Best Suspension System for Bicycles | BE Student

    Hello, I need to know what is the best type of susension system for bicycles.And also rating of a motor to drive a 5 kg load.I am still studying B E .Please it is urgent. Thaks for helping.
  20. Peter Hessellund

    Bingham plastic that is not a suspension

    I am looking for a Bingham plastic that is not a suspension. It can either be in the form of an additive to water or a non conductive chemical. The liquid should have a yield stress of 150 Pa to 250 Pa. What liquid could be used here? Are there companies who tailor make these kind of liquids?
  21. mattyboson12

    Material selection for vehicle leaf spring

    Homework Statement I've gone though a material selection process to pick the optimum material for a rear leaf spring suspension for a vehicle (~700mm long) and I've selected the top 10 materials based on fatigue, fracture, toughness, cost, yield etc: -Stainless steel, martensitic, AISI 440B...
  22. H

    Auto/Motor Front suspension for DIY scooter

    Hi I am new to this forum and I was referred to it by a friend. I am building an electric scooter and want to know how to add suspension/shock absorbers to it. I know the terrain I want to go over. Bumps of about 1-2 inch. My wheel size will be pretty small about 7-8 inches. I was looking to...
  23. K

    Updating the suspension of a car

    Homework Statement A car driver updates the springs of a car by replacing the old springs with stiffer ones. The old springs give an amount of 8 cm when under the car, and their length when not under the car is 29 cm. The spring constant of the new springs is 30 % greater than that of the old...
  24. Pao44445

    Suspension: Spring Constant Calculation for 500 kg Car

    Homework Statement A guy is 60 kg and he gets in a car which is 500 kg. the center gravity of the car is 0.3 cm lower, find the spring constant of the suspension Homework Equations F = -kx F = mg The Attempt at a Solution I got the answer but it s very low valve, the springs of the car should...
  25. R

    Admissions Please look over my Academic Suspension appeal

    Please help. I am not confident about my academic suspension appeal. Please help me with my grammar, spelling, punctuation. And if there is something wrong with my letter, please address it but don't be rude about it. I am worried someone might criticize my letter and start making judgements, so...
  26. yunias

    Automotive How to find "equivalent stiffness" of the suspension system?

    Dude i have a problem to find the equivalent stiffness (k') and damping (c') of this equation ? thank youvery much physics forum
  27. E

    Tension of Suspended Cable

    Homework Statement A 50.0 kg 6.00m awning is held up by a wire in the middle. A 15kg sign hangs at the end. Calculate the tension in the massless wire and the magnitude of the net force from the wall acting on the awning. The cable forms a 40 degree angle with the awning at the bottom right...
  28. B

    Calculating suspension requirements for a cart?

    Hi, I am building a cart for my dog to pull around. I am going to put my child in it once they are about 1. Something like this. The paths we plan to go on though are not very smooth so I want to fit some suspension to the cart to make a smoother journey. Now the weight of the cart will be...
  29. Ben Reade

    Calculating the force in suspension as a car hits the brakes

    Hello, Firstly thank you for reading my post. This is an interesting question I was wondering if anyone here could teach me how to work out. Say if you had a large go-kart (FSAE/Formula Student if anyone knows of that) and you were driving at 120kph and hit the brakes and stopped in 3 seconds...
  30. A

    Help with Laplace Transform

    Homework Statement Diagram for a vehicle suspension is given. Displacement of wheel is given by 'x' and and displacement of body is 'y'. Spring constant, k = (7*10^4) Nm Damping coefficient, c = (3*10^3) N/m/s mass,m = 250kg a) Make a Laplace Transform of system and utilize it to predict 'y'...
  31. M

    Can someone look over my appeal letter for academic suspension

    I am writing to appeal my academic suspension from XX University. I was not surprised, but very upset to receive a letter earlier this week informing me of my suspension because of failure to maintain adequate GPA. I would like to urge you to reinstate me for next semester.The failing grades and...
  32. synMehdi

    Automotive Car front suspension design

    Hi, I have a question concerning car front suspension geometry/design like the macPherson suspension. I would like to know the influence of geometrical factors in the suspension behaviour. The factors in which I'm interested are : spring/damper angle, spring/damper position relative to the wheel...
  33. Leon666

    3D Static Analysis of a Automotive Suspension

    Hello, my name is Leon and I attend to a Mechanical Engineering College. (I'm sorry for any grammar mistakes, English is not my first language) I'm trying to calculate the reactions of a Formula SAE car's suspension to the chassis, but I'm getting some strange answers. I hope someone here can...
  34. A

    Force needed to support Suspension of a Vehicle

    Homework Statement A model for the suspension of a vehicle is shown where the spring has stiffness k = 178 N/mm and an unstreched length of 347 mm. http://imgur.com/1dTVs12 Determine the value P and the force supported by member AB so that the suspension has the equilibrium position shown...
  35. H

    Suspension bridge problem

    Homework Statement [/B] A simple suspension bridge consists of a uniform plane horizontal rectangular roadway of mass M, freely supported by two sets of four equally spaced light vertical cables. Each set of four cables lies in the same vertical plane and is attached to one edge of the roadway...
  36. S

    Tuning a 3 link rear suspension for aggressive exit on 1/2 mile track

    I have a Asphalt Super that has a 3 link rear suspension with coil overs. I run a flat 1/2 mile track and no matter what I do to it I can't get aggressive on exit. We are very fast and winning races but when I pick up throttle I have to roll it to a mat or it will blow the rear tires off. Entry...
  37. D

    Modeling a (very simple) vehicle suspension

    Hi, I am generating synthetic images from the perspective of a moving vehicle, i.e. a camera mounted on a vehicle driving through a computer generated scene. Now i want to simulate the motions of the vehicle body that result from road roughness (bumps, patches). I modeled my road roughness...
  38. H

    Height adjustable Shock absorber possible?

    Greetings, in my total distraction of designing the ultimate Off-road/Overland vehicle, I've been thinking about the following matter: Is it possible that a vehicle can be raised/lowered by pumping/removing extra oil into the shock absorber? And if so, would it affect the ride? Could it be...
  39. T

    Calculating steering rack axial forces?

    Hello I tried to calculate the minimum force needed to apply on the knuckle to make a turn. The important factor is the normal load (due to the weight of the vehicle) when the vehicle is not moving. I know the kingpin angle, scrub radius, knuckle arm, caster. But I am not sure how to proceed...
  40. S

    Center of Gravity and Suspension of Object

    Hello everyone, I am trying to understand a center of gravity question regarding an object that is being lifted. I have a part that has a lifting circle that is used to put a hook through to hoist. The part needs to slide onto another part's surface that is about 30 degrees above the...
  41. J

    Weight Transfer in Car Tires, and Suspension

    I've been looking up how weight transfers between car tires in various forms of acceleration, and I've found some formulas. For linear acceleration, I found this formula on Wikipedia: ΔWeight = (accel) * (height of center of mass) * (mass) / (wheelbase) en.wikipedia.org/wiki/Weight_transfer...
  42. BastianQuinn

    Ring Suspension Between Binary Masses

    I'm having trouble conceptualizing the variables involved with this system, and I was wondering if some expertise might make the problem much simpler than I believe it to be. Two massive spherical bodies (Osmium, minimum radius 900km, 5.08m/s^2 surface gravity) orbit each other with a solid or...
  43. M

    Impact force calculation of a Full Suspension Mountain Bike

    Hello Folks! I want to find the maximum applicable force on a full suspension mountain bike and i will use this force on a FEA software structural analysis for a uni design project. This bike has a rear suspension with 400 lbs/in spring rate.Also rear wheel vertical displacement(travel amount)...
  44. A

    Magnetic Suspension: Calculating I2

    Homework Statement [/B] A long horizontal wire carries a current of I1 = 48.1 A. A second wire, made of 2.5-mm-diameter copper wire and parallel to the first but a distance d = 14.9 cm below it, is held in suspension magnetically. What is the current I2 in the second wire? (Enter a positive...
  45. G

    Backyard suspension bridge calculations

    Hi there, I'm planning to build a suspension bridge in my backyard and i'd like some help with sag and force calculations. The bridge will span 18m across a stream (anchor to anchor) in my backyard. I'll have 2 x strands of wire rope (1 at either side of the walkway) to span the gap. I've...
  46. Z

    Finding theta for Coloumb's law suspension

    Homework Statement Two spheres are suspended on strings and repel each other. Using the graphing function of your calculator setup and solve a formula to find theta. The length of the rope is 3.0m, q = 1.0e4 and m = .2 kg. Homework Equations F=k*q1*q2/r^2 The Attempt at a Solution Using...
  47. G

    Push Rod Suspension Geometry Question Camber Change Wheels

    Hey, I've spent ages trying to solve what seems to be a pretty simple geometrical problem and I was wondering if anyone could help me solve it/give me some tips. I am trying to model how the suspension of a car behaves as a result of a displacement of the wheels. What the attachment shows is a...
  48. B

    Suspension system, linear differential equation

    Homework Statement In the limit as t→∞, the solution approaches x(t) =K \sin[ω(t − t_0)] where K and t0 depend on ω. A>0 and ω≥0. Show that K(ω) = \frac{A}{\sqrt{ω^4 + 2ω^2 + 1}} . Homework Equations Here is the differential equation...
  49. T

    Ultrasonic Standing Wave Suspension could the transducer support itself?

    Ultrasonic Standing Wave Suspension could the transducer support itself? Essentially looking at items that state a surface area of 1m2 could support 11.5kn at 16 Watts (Hemsel, 2013) could the transducer suspend itself from the reflector using the same theory even though the suspension point is...
  50. marellasunny

    Relation between suspension switching frequency and body eigefrequency

    'Slow-active suspensions realize small switching frequencies to control low-frequency body movements,such as roll pitch and lifting motions.Fully-active suspensions reach switching frequencies,like semi-active suspensions,greater than the natural eigen-frequencies of the vehicle.'- an excerpt...