Steering system and suspension design for 2005 formula saea racer car a dissertation submitted by cristina elena popa in fulfilment of the requirements of courses eng4111 and 4112 research project towards the degree of bachelor of engineering mechanical submitted. After pointing out the limits of a fourbar steering mechanism, this article inves. This makes it difficult to make a rapid change in vehicle direction. Value of the gear ratio depends on the number of teeth on the driver, idler and driven gear. If you immerse yourself in this you will be confused with terms and formulas that make the situation very complex. The steering system in edvsm includes the steering gear ratio steer angle at the steering wheel divided by the steer angle at the axle.
On the other hand, replacing a worn, stock steering box with a new quick ratio steering box is much more affordable and delivers far better steering response. Mark the sidewall of a front and rear tyre at the contact point between tyre and ground. Finding gear ratios nyu tandon school of engineering. Typical steering systems differential steer trapezoidal tierod arrangement. Implementation of four wheels steering using 3way worm. Thppcf steering gear service manual trw automotive. Steering system and suspension design for 2005 formula. Steering ratio is the amount of rotation given to steering. Steering design for a formula saea open wheel race car a dissertation submitted by leslie rayner in ful. Steering systems steering gear system by varying the efficiency, the degree of reversibility a reversible gear transmits motion from steering.
A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Steering design for a formula saea open wheel race car. What is a steering ratio and how do you calculate it. The steering ratio can be equated to steering wheel travel to the rack travel steering ratiosteering wheel travel rack travel 6. The smallest number of teeth on a spur pinion and gear, onetoone gear ratio, which can exist without interference is np. Most of the steering ratio is developed in the steering mechanism. In order to implement the ratios used in the couplers shown in figure 6. Steering ratio is the ratio of the number of degrees turned at the steering wheel vs. Oct 25, 2017 understanding the terms like steering ratio and gear ratio. A higher steering ratio means that you have to turn the steering wheel more, to get the wheels turning, but it will be easier to turn the steering wheel. Gear ratio chart if you put on a set of tires that are 12 bigger in circumference that is the same as taking off 1 tooth from the axle adding one tooth to a 2 cycle should give 200 rpm more adding one tooth to a 4 cycle should give 100 rpm more if you add a tooth and gain less than that, the gear.
Dec 12, 2012 while a rackandpinion steering system provides a giant leap in steering precision, it is also a very expensive upgrade. Steering actuator drives the motor using the output current from the steering control ecu to. Although ackerman can be achieved by having different steer arm lengths on each side, i do not think this is optimum for cars running longer tracks. Steering and suspension systems must constrain the wheel if it is to stay, say, in the plane oa.
To sum up, gear ratio is used to calculate the resulting gear speed and torque. Oct 12, 20 ive been trying to figure out the relationship between steering ratio and the cfactor but have not figured it out yet. The gear ratio is the ratio of the number of teeth on each gear. Measure the distance from the end of the rack to an arbitrary point, turn the pinion one full revolution and then measure the distance again. Redesign of an fsae race cars steering and suspension. The belt runs from the drive pulley to a driven pulley. Relationship between the involute elements determination of base tooth thickness from a known thickness and viceversa. What is a steering ratio, gear ratio and variable gear ratio. To determine gear ratio of a gear train with 2 gears, start by identifying your gears. Variableratio rack and pinion can be made to improve both manual and. Since, in practice, the applications are very diverse, it is important to consider the given conditions by using appropriate factors s b, k a, l kh.
The values of steering effort, gear ratio, steering ratio for different predefined pinion sized are shown below, the table shows that the change in pinion size is directly proportional to the steering effort applied by the driver and the steering ratio. Gearing ratio definition, formula how to calculate. Also, take a look at some of our top rated mechanical engineering courses. The torque transmission ratio from steered wheel to steering wheel will change with steering angle. Steering ratio is an inherent design consideration. Show students how the gear ratio can be expressed as a fraction. Calculate a rack and pinion drive, how do you do that. The main objective of the gear box is to change the steering ratio of the vehicle between two settings one for higher ratio and one for lower. That is why we try to explain to you in this article how you can do such calculation the easiest. This ratio is used when the at steering wheel steer table option is selected.
For case study the high steering ratio is taken as 22. A variable ratio steering, is a system that uses different ratios on the rack, in a steering system. Rack and pinion drive calculation and selection the values given in the load table are based upon uniform, smooth operation, k h. Edvsm also incorporates an extended version of hvosms steer degree of freedom model. There are different types of steering systems front wheel steering system rare wheel steering system four wheel steering system four wheel steering system is arranged so that the front wheels roll without any lateral slip in this system, the front wheels are supported on front axle so that they can swing. Calculates the steering gear ratio based on tire angle signals and vehicle speed signals. Steering ratio the steering ratio is the ratio of how much the steering wheel turns in degrees to how much the wheel turns in degrees. Design and simulation of manual rack and pinion steering system. To determine the turns of the wheel, normally youd count the turns all the way from lock to lock. The specs for a standard gearbox is different with a variable ratio which makes it slower off of center and speeds up the more you turn. The number of teeth for spur gears is given by where k 1f fll1 for fulld tht th08f tbt th d ldepth teeth, 0. For most modern cars, the steering ratio is between 12.
It is the responsibility of the mechanic performing the maintenance, repairs or service on a particular thppcf steering gear to a inspect the steering gear for abnormal wear and damage, b choose a repair procedure which will not endanger hisher safety, the safety of others. Another key element of the steering rack design is the custom round rack gear. If you have a ws6 steering gear, its a constant ratio of 14. Analysis of vehicle static steering torque based on tireroad. Understanding the terms like steering ratio and gear ratio. Steering calculations trigonometric functions triangle scribd.
Drives the steering actuator based on calculation results of steering cooperative control received from the skid control ecu, and of steering gear ratio control. Steering ratio gives mechanical advantage to the driver, allowing them to turn the tyres with the weight of the whole car sitting on them, but. To test the system, you can test drive th e vehicle or use a scan tool to enter false vehicle speed inputs to check if the system is changing the amount of. Rodrigues institute of technology, vashi abstract this project aims at studying the designing of. The gear attached to the motor shaft is considered the first gear, or the drive gear, and the other gear, whose teeth are meshed with the drive gear, is considered the second gear, or driven gear. Design and optimization of the steering system of a formula. The principle is the same, but rather than number of rotations, the ratio determines the linear distance traveled by the rack with each rotation of the pinion. The second gear is called the secondary gear or follower gear.
Save yourself the headache and let us figure out your ringandpinion gear ratio. Gear ratio you can think of gear ratio as a multiplier on speedand a divider on torque. How to measure steering gear ratio cr4 discussion thread. Gear ratio calculator calculate the gear ratio you need. The ratio of your power steering gearbox will determine how quickly your vehicle reacts to your steering input. This relationship between the tooth ratio and the gear ratio is very important. Steering ratio is the ratio of input from the steering wheel in degrees to the output on the wheels in degrees. We can find the ratio of any two gears if we know the number of teeth on each of the gears. Use our simple gear ratio calculator to quickly find the correct gear ratio for your ring and pinion gear set.
The ratio is due to the angle or pitch of the teeth on the worm gear to the angle or pitch on the sector gear. The speed of a gear is number of revolutions it makes per minute rpm. The formula for calculating speed in feet per second is. The actual effort it takes to turn the wheel and engage the power assist. Through the calculations we can find out that for a turn of maximum radius 4. The steering ratio is the relationship between how far you turn a steering wheel and how far the actual wheels turn as a result. How to calculate steering system parameters like steering. Design methodology of steering system for allterrain vehicles. How do we know what the speed of our drive train is. Formulas for gear calculation external gears contents.
To understand gear ratio we suggest you first read this article on gear terminology various terms used in gears and various types of gears. In this short video, we will be understanding the concept called steering ratio. The steering ratio is the ratio of how far you turn the steering wheel to how far the wheels turn. You can calculate the gear ratio by using the number of teeth of the driving gear a. And similarly pinion size is inversely proportional to total steering lock to lock angle. To find the total ratio, use the pulley ratio formula.
Designing ackerman into your steering system allows the steering system to produce increasing amounts of toeout as the front wheels are steered, producing the toeout you need at the time you need it. Steering ratio is also determined somewhat by the effective length and shape of the teeth on the sector gear. Design and optimization of the steering system of a. A rackandpinion gear system consists of a round gear known as the pinion and a flat, toothed component known as the rack. Steering ratio refers to the ratio between the turn of the steering wheel in degrees or handlebars and the turn of the wheels in degrees the steering ratio is the ratio of the number of degrees of turn of the steering wheel to the number of degrees the wheels turn as a result.
A handcrank is attached to a drive pulley of 2 inches in radius. The two wheel steering system takes large radius of turning and requires more space. Redesign of an fsae race cars steering and suspension system. In order to determine both the speed and force of rotating axles, we need to calculate the gear ratio. In this section, the steering torque transmission ratio is investigated on the basis of the kinematic analysis. I am trying to find the gear ratio of my 83 cj5 because i swapped out the 258, 4 speed with a 304, 3 speed and now i am having issues with the it. To calculate the group of curves a given steering angle range h must be assumed. The steering wheel must be turned one revolution to turn the front wheels one sixteenth of a turn, the steering ratio is 1 to 116. All vehicles today have a fixed or set steering ratio for their steering mechanism depending upon the type and. At the start of a vehicle dynamics study the steering ratio can be a model design parameter.
Pdf design and fabrication of variable steering ratio. The size of the pinion gear and the number of teeth on the gear determine the rackandpinion steering ratio. What is a steering ratio, gear ratio and variable gear. Some of the exceptions were the 1969 camaro and some full size pontiacs that had the popular 16. Steering wheel lock to lock angle is the total rotating capacity of the steering wheel i. Determining gear ratio, rolling circumference and front. Unit one steering system design 47 a4u1l3 figure 5 speed controlled variable power steering gear the system provides full assist for evasive maneuvers at higher speeds. A variableratio steering, is a system that uses different ratios on the rack, in a. For the tire field, enter your tire diameter in inches. Selection, modification and analysis of steering mechanism. A lower steering ratio means that you have to turn the steering wheel less, to get the wheels turning, but it. In racing events such as baja sae, formula racing where a driver is required to. Cylindrical spur gears with standard profile cylindrical spur gears with corrected profile without centre distance variation with centre distance variation. As the ratio is raised, a large number of turns are required to move the wheel from lock to lock.
This calculation helps in determining how leveraged is the firm is and how stable is the firm in repaying their debts and also continue with their expansion plans without affecting its profitability as well. Heres an illustrative calculation the ackermann principle as applied to steering automobile 2. In the low to mediumspeed range, which is used when driving on city streets or on a winding road, this system changes the steering gear ratio to an optimal level in accordance with the vehicle speed. We gear up when we increase velocity and decrease torque. Calculating rackandpinion gear ratio instead of counting the number of teeth in each gear, measure the distance the rack moves in inches. Mechanically variable steering ratio gear box devanjan mishra1 corresponding author. Steering system the steering system in edvsm includes the steering gear ratio steer angle at the steering wheel divided by the steer angle at the axle. Pdf design and fabrication of variable steering ratio mechanism.
Design methodology of steering system for allterrain. Because, it can give two benefits, reduced steering angle rotation with larger angular rotation of tires. Variable steering ratio, continuous meshing gear box, active steering, manually. Steering calculations for a rack and pinion steering system used in baja. The motor turns this gear and it makes the second gear turn in the opposite direction. Us7278512b2 variable gear ratio hydraulic power steering. Pdf the steering effort is an important characteristic of vehicles because it influences driver comfort directly. It allows us to find a gear ratio without actually having to build a gear train and turn the gears. Steering system calculation method revised 5312000 4 3. Steering rack and pinion calculation stepbystep plans.352 264 300 616 989 57 524 1267 133 605 373 1295 942 730 368 957 1090 893 49 650 667 159 211 300 1363 410 1157 347 411 883 1274