Axle bearings, the fundamental ones are those on the rear axle

AXLE BEARINGS

TKART Staff

23 May 2016

Bearings have a key role in the functioning of the chassis, because they reduce friction and the wear of the components. The fundamental ones are those on the rear axle

WHAT IS IT?

HOW DOES IT WORK?

IN PRACTICE

Each component of the chassis, but also of the engine, which has to rotate with respect to the element it is connected to, is normally mounted on bearings. This allows, especially when the forces and speeds involved are high, a great reduction in friction, wear and the heat generated between the elements in contact. The example par excellence, in karting, are the rear axle bearings: usually two in the past, three are now increasingly used, one on the left axle and two on the right, also to compensate for the presence of the engine and its loads.
Basically, a bearing is made of two steel rings with rotating elements inside: spheres, cylinders, cones or rollers. These are held in position by a metallic or plastic cage which

keep the rotating bodies apart, preventing any contact between them, so as to minimise the friction and, therefore, the generation of heat.
The axle bearings are usually of a radial type with a single ring with spherical elements, which allow higher rotation speeds and lower friction compared to, for example, roller bearings.
Even the supports for the bearings vary in terms of the number of fixing screws to the chassis and form, determining more or less rigid structures depending on the manufacturer’s choices. Generally, the supports have a diameter adjustment system that allows the tightening or loosening of the bearing and the recovery of the play due to wear.

BALL BEARINGS ARE THE BEST KNOWN BEARINGS. HOWEVER THERE ARE MANY TYPES, DEPENDING ON THE FORCES THEY HAVE TO SUPPORT AND THE ROTATION SPEED

BEARING HOUSING CASES

Each manufacturer inserts the bearings in specific bearing housing “cases” of different shapes and with different characteristics. Here is an example of some of the most common ones.

WHAT IS IT?

HOW DOES IT WORK?

IN PRACTICE

BEARINGS

SPHERICAL ROLLER

CYLINDRICAL ROLLER

NEEDLE ROLLER

TAPERED ROLLER

There are many parameters that characterise bearings: firstly, the dimensions of the inner and outer ring, both the inner and outer diameters, as well as the width. The measures have been standardised by the ISO in order to achieve standard and coded values.
Another parameter that defines a bearing is the inner play, that is, the total possible displacement in the radial or axial direction. The radial ball bearings must have a play practically equal zero or with a slight preload. Bearings with internal play that is different from the standard are marked with suffixes C1 to C5.