teshimaryokan.info Fiction FOUR WHEEL STEERING SYSTEM PDF

Four wheel steering system pdf

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steering vehicle is proven to be low compared to the four wheel steering vehicles. Four wheel steering system can be employed in some vehicles to improve. Four Wheel Steering System. 1,2,3&4 U.G. Students, Department of Mechanical Engineering, IMS Engineering College, Ghaziabad. 5 Assistant Professor. The 3MI 4WS system assists driver by controlling the steering angle of a vehicle's four wheels as the requirement of driver, for making the parking and handling.


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PDF | Nowadays, the every vehicle existed mostly still using the two wheel steering system to control the movement of the vehicle whether it is front wheel drive. Four-wheel steering is a serious effort on the part of automotive design engineers to provide near-neutral steering. Also in situations four wheel steering systems, where the rear wheels turn .. l_papers/jpdf, Retrived on 20th Oct This paper is all about 4-wheel steering system rather than 2-wheel steering as in conventional vehicles running in INDIA. A 4-wheel steering is completely.

The transfer rod is connected to the knuckle arm of steering gear using a steering knuckle. There is also less sway when the wheels are turned back to a straight-ahead position. The tires are subjected to road grip and slip angle. There is also less sway when the wheels are turned back to a straight-ahead position. Suspensions in rear wheels demands considerable changes for proper working of the vehicle with varying load. The steering gear box is fitted to the end of this column.

After welding ring with the spokes is ebonite moulded on it. One end of the pipe is fixed on the steering box, while the other end is usually held with the help of bracket under the instrument panel.

One end is fixed in the steering wheel with the help of splines or key and kept tight by nut. The other end with worm is secured firmly in the steering box with the help of bearing placed both on top and bottom. Sometimes, instead of one shaft, two pieces of shaft are also used. Its one side is provided with splines which match the spline sector shaft and held on sector shaft by nut.

The other end has a tapered hole in which ball end is held tight with the help of nut. The steering gear box is fitted to the end of this column. Therefore, when the wheel is rotated, the cross shaft in the gear box oscillates. The cross shaft is connected to drop arm. This arm is linked by means of a drag link to the steering arm. The steering arms on both wheels are connected by tie rod to the drag link.

When the steering wheel is operated, the knuckle moves to and fro, moving the wheels to the right or left. One end of the drag link is connected to the tie rod.

The other end is connected to the end of drop arm. A ball and socket joint gives the required movement to the joints between the tie rod, drag link and drop arm.

When the vehicle is moving, the drop arm develops the vibration. Shock springs are used in ball and socket system to absorb this vibration. But this may be difficult to arrange in practice with simple linkages. Hence, modern cars do not use pure Ackermann steering, partly because it ignores important dynamic and compliant effects, but the principle is sound for low speed manoeuvres.

The steering ratios generally used with present day steering gears vary from about An average overall ratio usually gives about one and half complete turns of the steering wheel each side of mid position to apply a full lock of 45 degrees each way on the wheels.

Wheel system four pdf steering

There is no hard and fast formula to calculate the turning circle but an approximate value can be obtained using the formula: This can be achieved if the axis of all four wheels intersects at one point. This point will be the centre about which the vehicle will be turning at that instant. Figure shows the steering geometry of the four wheels of a vehicle. The rear wheels rotate along two circles. The centres of both these circles are at O.

The front wheels 1 and 2 have different axes. They rotate along two other circles with the same centre point. For correct functioning of any steering system, the centre of the wheels of the rear axles and of wheels 1, 2 should coincide.

A wheel is said to have directional stability or control if it can: Run straight down a road Enter and leave a turn easily Resist road shocks Factors pertaining to steering geometry are: The angle between the vertical line and centre of the king pin or steering axle, when viewed from the front of the vehicle is known as king pin inclination or steering axle inclination.

It helps the car to have steering stability It makes the operation of the steering quite easy particularly when the vehicle is stationary. It helps in reducing the wear on tyre Fig.

The combined camber and king pin inclination is called included angle. It determines the point of intersection of the wheel and king pin centre lines. This in turn determines whether the wheel will tends to toe-in or toe-out If the point of intersection above the ground, the wheel tends to toe-in If it is below the ground, the wheel tends to toe-out If it is at ground, the wheel keeps its straight position without any tendency to toe-in or toe-out.

In this position the steering is called centre point steering. In addition to being tilted inward toward the centre of the vehicle, the king pin axis may also be tilted forward or backward from the vertical line. This tilt is known as caster.

Thus the angle between the vertical line and the king pin centre line in the plane of the wheel when viewed from the side is called caster angle. Positive caster: If the king-pin centre line meets the ground at point ahead of the vertical centre line.

Negative caster: If the king-pin centre line meets the ground at point behind the vertical centre line. The purpose of the caster is to give a trailing effect to the front wheels. When the wheel trails the line of weight that moves in the same direction as the vehicle it is easy to steer a straight course.

Positive caster in wheels results in a natural tendency in wheels to toe-in. When both the front and rear wheels steer toward the same direction, they are said to be in-phase and this produces a kind of sideways movement of the car at low speeds. When the front and rear wheels are steered in opposite direction, this is called anti-phase, counter-phase or opposite-phase and it produces a sharper, tighter turn.

To understand the advantages of four-wheel steering, it is wise to review the dynamics of typical steering maneuvers with a conventional front -steered vehicle. The tires are subject to the forces of grip, momentum, and steering input when making a movement other than straight-ahead driving. These forces compete with each other during steering maneuvers. This causes the vehicle to sway.

Each of these must be balanced against the others. The tires are subjected to road grip and slip angle.

Steering input causes the front wheels to turn. The car momentarily resists the turning motion, causing a tire slip angle to form. Once the vehicle begins to respond to the steering input, cornering forces are generated.

The vehicle sways as the rear wheels attempt to keep up with the cornering forces already generated by the front tires. This is referred to as rear-end lag, because there is a time delay between steering input and vehicle reaction. When the front wheels are turned back to a straight -ahead position, the vehicle must again try to adjust by reversing the same forces developed by the turn. As the steering is turned, the vehicle body sways as the rear wheels again try to keep up with the cornering forces generated by the front wheels.

The idea behind four-wheel steering is that a vehicle requires less driver input for any steering maneuver if all four wheels are steering the vehicle. As with two-wheel steer vehicles, tire grip holds the four wheels on the road. However, when the driver turns the wheel slightly, all four wheels react to the steering input, causing slip angles to form at all four wheels.

Four Wheel Steering report

The entire vehicle moves in one direction rather than the rear half attempting to catch up to the front. There is also less sway when the wheels are turned back to a straight-ahead position. When both the front and rear wheels steer toward the same direction, they are said to be in-phase and this produces a kind of sideways movement of the car at low speeds.

When the front and rear wheels are steered in opposite direction, this is called anti-phase, counter-phase or opposite-phase and it produces a sharper, tighter turn. Easier to construct, more reliable, less components. Easier to design, identical geometry and components for subsystems. And a bevel gear arrangement is made just after the steering and power is transmitted through the transfer shaft to the gear box assembly.

Four-Wheel Steering System | Seminar Report, PPT, PDF for Mechanical

Then power is transmitted to the rear wheels. Two subsystems: Rack and pinion for front and rear, identical geometry and components. Steering column is fitted with 3 bevel gears meshes and transmits power to front and rear rack and pinion. As steering wheel is turned the entire rotation is transferred to front rack and pinion and only half of the rotation is transferred to rear rack and pinion.

To understand the advantages of four-wheel steering, it is wise to review the Page6. These forces compete with each other during steering maneuvers. With a front-steered vehicle, the rear end is always trying to catch up to the di- rectional changes of the front wheels. This causes the vehicle to sway. As a normal part of operating a vehicle, the driver learns to adjust to these forces without thinking about them.

When turning, the driver is putting into motion a complex series of forces. Each of these must be balanced against the others.

Pdf system four steering wheel

The tires are subjected to road grip and slip angle. Grip holds the car's wheels to the road, and momentum moves the car straight ahead. Steering input causes the front wheels to turn. The car momentarily resists the turning motion, causing a tire slip angle to form.

Once the vehicle begins to respond to the steering input, cornering forces are generated. The vehicle sways as the rear wheels attempt to keep up with the cornering forces already generated by the front tires. This is referred to as rear- end lag, because there is a time delay between steering input and vehicle reaction.

When the front wheels are turned back to a straight -ahead position, the vehicle must again try to adjust by reversing the same forces developed by the turn. As the steering is turned, the vehicle body sways as the rear wheels again try to keep up with the cornering forces generated by the front wheels.

The idea behind four-wheel steering is that a vehicle requires less driver input for any steering maneuver if all four wheels are steering the vehicle.

As with two-wheel steer vehicles, tire grip holds the four wheels on the road. However, when the driver turns the wheel slightly, all four wheels react to the steering input, causing slip angles to form at all four wheels.

The entire vehicle moves in one direction rather than the rear half attempting to catch up to the front. There is also less sway when the wheels are turned back to a straight-ahead position. The vehicle responds more quickly to steering input because rear wheel lag is eliminated.

All 4WS systems have fail-safe measures. For example, with the electro- hydraulic setup, the system automatically counteracts possible causes of failure: Specifically, if a hydraulic defect should reduce pressure level by a movement malfunction or a broken driving belt , the rear-wheel-steering mechanism is automatically locked in a neutral position, activating a low-level warning light. In the event of an electrical failure, it would be detected by a self-diagnostic circuit integrated in the four wheel-steering control unit.