Comparison

Why Polybush your Bus

A European bus manufacturer was looking for a link bush that would offer the ultimate performance and longevity. Using the Millbrook Proving Ground in Bedfordshire, they compared standard rubber bushes with Polybush The tests were repetitive +/- 80mm anti-roll bar movement cycles on a fixed test bed plus ride comparisons on a road vehicle. The results were: The rubber bushes failed after 5,000 to 15,000 cycles Our Polybushes lasted 55,000 cycles Our Polybushes were measured at 10 - 15 degrees celcius cooler than the rubber bush while operating on the test bed Our polybushes did not change the ride of the vehicle Bonaprene Products are now a supplier of a range of Polybush parts to European bus manufacturers.

 

Mercedes Buses

The Mercedes 309-814 and Vario range of buses are the workhorse of the First Bus, Stagecoach and Arriva bus fleets.

The constant stop-start regime, poor roads and speed bumps cause havoc to their van derived suspensions. High bush wear leads directly to the bus not being out earning money.

For over 10 years we have been supplying the after sales market with Polybush link, spring eye, anti-roll bar clamp and shock absorber bushes for this range of buses. Our specially designed link bush is shown below:

These link bushes trialed at Travel West Midlands and First Bus PMT exceeded 50,000 miles of 12 months and still did not need replacing. This compared exceptionally well with the 6 - 8 weeks and 6,000 miles that they used to get with rubber bushes.

Compression Deflection Tests A customer asked us to compare samples taken from a problem suspension bush with two possible Polybush alternatives. The customer's bush was permanently compressing under load and then splitting radially. The samles were compressed at 30mm per minute to 50% of their original thickness and relaxed at the same rate. This cycle was repeated without interruption over 20 cycles. The actual force and reduction in force between the first and last cycle were:   Max force 1st cycle Max force last cycle Force loss Polybush 65 °A 1644 N 1614 N 1.8% Polybush 75 °A 2756 N 2656 N 3.6% Original rubber bush65 °A 1912 N 1700 N 11.1% The table shows how quickly the rubber permanently compresses compared to the equivalent hardness of Polybush. Once in this state, the rubber's resilience and ability to flex is geatly reduced causing splitting and failure.