Product category:
Bearings
News Release from: SKF UK | Subject: CARB bearings
Edited by the Engineeringtalk Editorial
Team on 12 October 2001
Volvo engineers improve on plain
bushings
In the new Volvo A35 hauler, the two hydraulic cylinders within the steering mechanism are fitted with low profile, sealed for life, CARB bearings from SKF
Heavy hauling trucks, used in the mining and earth moving industry, are subjected to wet and dirty conditions with repeated shock loads As a result, engineers at Volvo Articulated Haulers, part of the Volvo Construction Equipment Group, selected SKF's CARB toroidal roller bearings for the steering mechanisms of their vehicles
This article was originally published on Engineeringtalk on 14 Jul 2004 at 8.00am (UK)
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In the new Volvo A35 hauler, the two hydraulic cylinders within the steering mechanism are fitted with low profile, sealed for life, CARB bearings (type C6912-2NSV).
The cylinders, one mounted on either side of a central pivot joint, swing the front tractor unit and separate the rear trailer about the pivot by synchronised extension and retraction.
The bearings are subjected to very high shock loads in combination with small oscillating movements and deflections.
Traditionally, the hydraulic cylinders would have been fitted with plain bushings, which are prone to damage under these conditions.
Moreover, the plain bushings rely on a large sliding bearing surface which is very difficult to lubricate for long lasting protection.
CARB overcomes these problems by employing a large number of long, small diameter rollers that are fully surrounded by high quality grease.
These rollers only need to rotate through a very small angle for the load carrying contact to be made between the lubricated surfaces.
Volvo subjected the CARB bearings to extensive and rigorous testing, both in the laboratory and in long term field service.
The findings confirmed that CARB's wear rate is negligible, even under oscillating shock loads, and that bearing friction is low compared with plain bushings.
Using CARB provides a number of other advantages such as no relubrication requirements, which reduces service costs.
Furthermore, no grease can escape which means there is no environmental impact - a factor Volvo insisted upon.
The accuracy of the steering motion is also assured, as the radial clearance in the bearing is very small and does not increase over the life of the machine. Request a free brochure from SKF UK ...
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