The axis of the pendulum arm can rest on the bushings

or on rolling bearings. What to prefer?

Alexander BUDKIN

Beginning motorists - owners of the Lada will learn about the existence of the pendulum lever, as a rule, having felt an increased backlash in the steering. Its cause is often a clearance in the bushings of the swingarm arm of a conventional design (with plain bearings). How does it arise?

The forces acting in the steering trapezoid of the Zhiguli when the steering wheel rotates in place or in a collision with a small speed on an obstacle 5-6 cm high, as a rule, do not exceed 150-200 kgf. At the same time, a force that is two times smaller is acting on the axis of the pendulum lever. With such loads and sliding speeds of the bushings less than 1 m / s, the wear resistance of the sliding bearing should be more than sufficient. And given that such loads occur occasionally, and most of the time forces are several times smaller, the lever could survive the car. In actual operation, he rarely nurses more than 50-80 thousand km, and sometimes even less. The reason is offensively simple - abrasive wear, despite all attempts to make the unit airtight. The internal cavity of the lever housing is isolated from the external environment by two rubber rings 7 in the figure, the steel clamping washers 6 and 10 rub against their end surfaces. Even when immersed in water, the assembly must remain airtight, but …

Since there is enough dirt on the roads, it covers the joints of the sealing rings with steel washers during movement (indicated by arrows in the figure). And when the car drives into bumps, under the influence of vibrations, the dirt "pulls" into the lever. This happens as follows: the vibration of the lever makes it oscillate in the axial and radial directions and at the same time slightly rotate. As a result, each point of the metal washer moves in a spiral, capturing small particles of abrasive from the surface of the rubber ring and dragging them into the bowels of the assembly. The result is the inevitable, sooner or later, replacement of the lever bushings.

The way out of the situation was invented for a long time. Since 1994, pendulum arms with rolling bearings began to be installed in series with RAF minibuses. Their radial clearance is minimal, and closed-type modifications (with seals) are not subject to abrasive wear and do not require replenishment of grease.

Owners of even the latest rear-wheel drive VAZs in this sense were unlucky. To this day, they still have to buy and install a more durable pendulum lever on their own. Together with them we will go to the store and we.

Without much work in the capital's shops acquired four swingarm. Moscow - with rolling bearings without a through hole in the housing (photo 1), Vladimir - with rolling bearings having their own seal and a rubber cap (photo 2), Tolyatti - similar to its predecessor, with dirt washers, but without seals (photo 3), and, finally, the usual Togliatti - with sliding bearings (bushings), corresponding to the VAZ documentation. No product has factory marking, so their true origin is largely on the conscience of sellers.

The “lice” test conducted by NAMI specialists included two tasks. Initially, the radial displacement of the axis of the lever under the action of a bending load of 40 kgf at its end was measured. Then we checked the tightness of the products, placing them for four days in the water. For greater objectivity, the levers were periodically turned left and right by 180 °. The results were quite expected (see photo captions). Moscow and Tolyatti products were leakproof. Vladimirsky and another Togliatti (photo 3) nodes flooded the water. When checking the stiffness, there were no surprises either: the product with sliding bearings (bushings) showed a 0.12 mm displacement, the rest showed less than 0.02 mm, keeping within the error of the measuring stand.

CONCLUSIONS: Moscow leverage should serve faithfully as much as the car itself. "Vladimir" and "Togliatti" with rolling bearings have a chance to repeat the feat of the "Muscovite" provided they are lubricated. Well, the properties of an ordinary VAZ lever are already well known to everyone.

1. Made in Moscow

Price - 200 rubles.

Ball bearings with shields, there is no through hole in the housing, the bottom axis has a mechanical seal with a steel washer and rubber ring. The case is tight. Case material not specified.

2. Manufactured

in Vladimir

Price - 190 rubles.

Ball bearings with their own seal, on top of the housing is a rubber cap. The housing is leaky. Case material - AL35. A grease hole is not provided.

3. Made in Togliatti

Price - 180 rubles.

Open ball bearings, no seals, dirt protection - with steel washers - reflectors above and below. Has a plugged hole for lubrication. The housing is leaky. Case material not specified.

4. Made in Togliatti

Price - 160 rubles.

Corresponds to the documentation of VAZ, as sliding bearings - polymer bushings, mechanical seal with steel washers and rubber rings. The case is tight. Case material - AL9.