In short, the essence of the improvement is this: the wheels are attached to the MacPherson struts through the steering knuckles. Structurally, the performance of such a suspension may vary somewhat, but the principle of dividing the classic rack into swinging and swivel parts remains unchanged. The names for their versions of the "fist" MacPherson manufacturers invent each in its own way. For example, the French from Renault, perhaps the first to apply such a scheme, call it pseudo-MacPherson. Fordovtsy for the suspension of the “evil” Focus RS came up with a more authentic: RevoKnuckle - that is, a swivel (or maybe revolutionary - understand how you want) hinge. GM called a similar suspension HiPerStrut - Hi Performance Strut. At first, she appeared on the 325-horsepower Opel Insignia OPC, and then migrated to other models of the concern, in particular, the Opel Astra GTC, Buick LaCrosse CXS and Buick Regal GS.
Opel Astra GTC
Opel Astra GTC
Fists and shoulders
So what do these very individual knuckles give? To appreciate the benefits of an improved design, you have to remember what the “running-in shoulder” and “power steering” (torque steering) are. The first one is easy to understand according to the figures, and the second, as you know, is a front drive wheel pull under one-way traction. In other words, when you press the accelerator pedal, the car tends to the right or to the left, and the steering wheel tries to “escape from the hands”. This effect is more pronounced on powerful front-wheel drive cars, although on some quiet family “sneeze” it is also noticeable with a sharp start or acceleration in lower gears.
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One of the first to use the improved suspension was the French on the Renault Megane Sport, mounting the steering knuckle (1) on an almost standard strut (2). And in order to avoid the rotation of the rack, it was fixed with an additional rod (4), fastened with the second end to the wishbone (3). One of the first to use the improved suspension was the French on the Renault Megane Sport, mounting the steering knuckle (1) on an almost standard rack (2). And in order to avoid turning the rack, it was fixed with an additional rod (4), fastened with the second end to the wishbone (3)
One of the ways to reduce power steering is to reduce the running-in shoulder, that is, the shoulder, on which the forces creating a parasitic moment act. The steering knuckles attached to the swinging rack, just allow you to solve this problem. In addition, the upper mounting point of the rack no longer needs a thrust bearing, because the column itself now does not rotate, but only sways in the transverse direction.
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The HiPerStrut racks (1) that appeared later, developed by GM engineers, are connected to the wishbones (2) via the silent block (3), rather than the ball joint and cannot rotate. The steering knuckle (4) is attached to the bottom of the strut on the ball bearings (5) The later-developed struts (1) HiPerStrut, developed by GM engineers, are connected to the wishbones (2) via the silent block (3), and not the ball bearing and not can rotate. The steering knuckle (4) is attached to the bottom of the rack on ball bearings (5)
Matter in price
These are the pluses. But there are also disadvantages. In addition to the obvious complication and appreciation of the suspension and its subsequent repair, the appearance of knuckles leads to an increase in unsprung masses. And this, in turn, negatively affects the ride. That is why the "fist" MacPherson is so far mainly distributed on charged front-wheel drive cars, in which handling is given an absolute priority over comfort, and the increase in the cost of the suspension is dissolved in a rather big price. And most importantly - the effect of the use of "hyperstands" is much more noticeable.
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The Ford RevoKnuckle racks are basically the same as the HiPerStrut. The only difference is the design of the steering knuckle (1), the lower part of the strut (2) and the interface (3) of the strut with the wishbone (4). Ford RevoKnuckle struts are basically the same as HiPerStrut. The only difference is the design of the steering knuckle (1), the lower part of the strut (2) and the interface (3) of the strut with the wishbone (4)
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Here, using the example of the Ford RevoKnuckle suspension, it is clearly seen how the use of steering knuckles reduces the so-called break-in shoulder, the value of which is equal to the distance between the line formed by the intersection of the plane of symmetry of the wheel with the road and the point of intersection of the axis of rotation of the wheel Here, using the example of the Ford RevoKnuckle suspension it can be seen how the use of knuckles can reduce the so-called running-in shoulder, the value of which is equal to the distance between the line formed by the intersection of the plane s metry wheel to the road, and the intersection point with her wheel rotation axis
