Precise plain bearings in steering rod: even on bumpy track without clearance

Profile

• What was needed: iglidur J​​​​​​​ plain bearings
• Requirements: No play to the steering rod, easy integration into the existing installation space, low friction, vibration damping, wear-resistant, self-lubricating, environmentally friendly, durable, lightweight, dirt-resistant, maintenance-free, and usable at temperatures from -40 to 120°C
• Industry: Automotive
• Success for the customer: The new iglidur J bearings reduce the BSR score (noise indicator) from 800 to 8 (the smaller, the better the performance); the drive quality improves noticeably, and the car manufacturer makes great financial savings by eliminating warranty claims; all in all, the solution is effective and low-cost

Problem

One of the automotive industry's great challenges is stabilising components on uneven terrain so that they generate no BSR (buzz, squeak and rattle) noise. Noise in cars is one of the most irritating issues for customers and costs OEMs a great deal of money in warranty claims. Squeaking is a noise caused by friction between two mating surfaces, while a rattling is caused by impact resulting from momentary loss of contact between surfaces. The main causes of these noises are low tolerances, incompatible material pairs and structural deficiencies. 
TATA Motors faced these exact problems with the supporting structures for its steering rods, which initially consisted of a polyacetal ball bearing.
The manufacturer studied the problem thoroughly and compiled a list of requirements for a new solution. A requirement was that the bearing should have no play towards the steering rod, but at the same time enough play for quick and easy mounting. The solution must also be integrated quickly into the existing installation space without modification. The bearing material must also be low-friction, vibration-damping, wear-resistant, self-lubricating and environmentally friendly. It must be durable, lightweight, and resistant to dirt and require no maintenance. Finally, the bearing products had to operate without problems at working temperatures of -40 to 120°C.

Solution

The stringent requirements on the bearing solution demanded a well-thought-out material. TATA Motors finally found the answer in our iglidur bearing solutions, specifically the iglidur JVSM bearings.
These bearings are equipped with springs that allow radial preload and thus tolerance-free travel. The iglidur J material also offer several other advantages that this application demanded.
The material was originally intended for clutch and brake pedal applications but the company tried it with the existing structure in the steering rod. This greatly improved BSR (buzz, squeak, rattle) performance. The carmaker documented the performance in its own testing procedures and scored the new solution. While the old solution's BSR score was 800, the iglidur J bearings achieved 8 (the smaller the score, the better the performance).
The improvements had a very positive impact on the overall ride quality. High costs in the form of warranty claims for the steering system were also eliminated. All this was achieved with a simple design at minimal cost. Once the carmaker was satisfied with the test results, it implemented the solution in the production process.