Suspension is one of the main mechanisms in the construction of any vehicle. Thanks to her, the car is able to move along uneven sections of the road, reducing impacts and vibrations. Also, the suspension is the link between the wheels and the body. The system provides an elastic bond between these elements. Today, there are several types of chassis. However, one of the most common is the MacPherson strut. The device, features, pros and cons, we will consider it in our today's article.
Characteristic
This system is the most popular for the front chassis of the car. It is used on all machines of the budget and middle class. A key feature of the McPherson type suspension is its compactness.
Due to this property, the system can be used on front-wheel drive cars and not interfere with the transverse placement of the engine with gearbox. Also, the characteristics of many include simplicity of design and ease of maintenance. The MacPherson strut suspension itself is a continuation of the classic suspension design with double wishbones. However, in this case, the upper arm is replaced by a shock absorber strut.
Device
The design of this system includes the following elements:
- Hub.
- Brake disc with protective cover.
- Spherical bearing.
- Swing arm.
- Coil spring.
- Lower and upper support cup.
- Pillow block bearing.
- Case Rack.
- Compression buffer with support.
- Stock.
- Rounded fist.
- Lower arm.
- Drive shaft (external joint of equal angular speeds).
- Hinge cover (is a rubber boot, which is connected by clamps).
Next, we consider the main structural components of an independent MacPherson strut.
Stretcher
This is the main bearing in the front chassis. The subframe is fixed by means of silent blocks to the car body. The use of such rubber-metal bearings can reduce noise and vibration during operation of the chassis. Some models require rigid subframe fasteners to the car body.
But regardless of the method of attachment, the support of the transverse lever, the steering gear and the anti-roll bar are also brought to this element.
Wishbones
These mechanisms are attached to the subframe on both sides. Distinguish the wishbone of the right and left wheels. The connection is made by means of rubber bushings, which also partially dampen vibrations and vibrations. The dual mounting method serves to achieve greater structural rigidity in the longitudinal direction. Also, the wishbone is connected to the steering knuckle (however, not directly, but through the ball bearing).
Rounded fist
There are only four of them. The fist stands on the right and on the left side, in the upper and lower parts. What is this part used for? It is necessary so that the wheel can make a turn. The fist in the upper part is fixed to the stand using a terminal connection.
At the bottom, the element is mounted with a wishbone (as we said earlier, by means of a ball joint). Also in the fist is the brake caliper and bearing assembly. The latter assumes the presence of a hub along with a needle bearing.
Shock absorber
It plays the role of an elastic element. It consists of two parts:
- Shock absorber.
- Helical spring.
The latter is coaxial with the shock absorber and is mounted on a rack. To change the spring characteristics of the spring, a compression buffer is also set here. At the bottom, the strut is connected to the steering knuckle. At the top, it is attached to one of the power parts of the body, namely to the mudguard of the engine.
Anti-roll bar
It is an integral part of the MacPherson strut front suspension. This element serves to reduce lateral rolls when cornering at speed. The stabilizer is made of elastic grades of steel and is fixed with two supports on a subframe. At the ends there are connecting rods with articulated tips.
Pros of McPherson Suspension
As we said earlier, this system has small dimensions. From this it is worth concluding that the mass of such a suspension is several times less than that of any other. Thus, it is ideal for small cars. The low weight of the system has a positive effect on reducing fuel consumption.
Another MacPherson strut suspension has a large margin of safety. She is pretty reliable. There are not so many connecting sections and structural elements. Thanks to the mount to the mud flaps and the presence of a stabilizer, the system reduces lateral and longitudinal rolls. The next plus is the low cost and ease of installation. In view of this, the price of the car itself is significantly reduced.
The indisputable advantage of such a suspension is a large resource of its elements. So, the most “tenacious” on our roads are leverage. They can walk up to 200 thousand kilometers. And you can replace only the silent block (although on some models the lever changes with the rubber sleeve). Wheel bearings and ball bearings have a resource of 80 thousand kilometers. The stand can walk up to 120 or more thousand. In terms of repair costs, this suspension is very cheap. Many parts can be replaced with your own hands.
Another plus is the possibility of self-diagnosis. By the characteristic rumble on the corners, it can be determined that the hub bearing is out of order. A crunch when turning indicates failure of the pillar support bearing. And the deaf knocks and the buildup of the body at speed indicates wear on the shock absorber. Backlash of parts can be checked independently with the help of a mount, having an inspection hole available.
Minuses
But not everything is as smooth as it seems at first glance. This suspension is not used on all cars without exception, and there are reasons for this. The first is kinematics. The strut has a large stroke and articulation. Because of this, the angle of inclination of the wheels relative to the vertical plane changes significantly. Because of this, MacPherson strut is not used on sports and premium cars. Large strokes lead to insufficient contact of the wheels with the road and loss of control at high speeds.
Also, all loads (shock and vibration) are transmitted directly to the body. These loads are especially intensified when driving on rough roads. Because of this, over time, the mounting of the rack with the body splash guard collapses. Cracks appear in certain places. The fact that most of the suspension struts are non-separable also spoils the picture. Therefore, in case of failure of the shock absorber, you need to buy a completely new rack.
But in most cases, manufacturers refuse such a suspension due to the fact that it does not have a high ride. No matter how soft the shock absorbers are, the MacPherson strut will always be stiffer than the multi-link. Also, this suspension is very noisy. Therefore, such a system can not be found on business class cars and above.
To summarize
So, we found out what the pros and cons of MacPherson strut have, and also examined its device. As you can see, this system is far from suitable for all cars. It has certain limitations, and therefore is used mainly on cheap front-wheel drive cars. At the same time, do not refuse to buy a car with such a chassis. After all, it will be much cheaper to maintain.