Plastic bearing solution resolves friction problem

Edited by the Engineeringtalk editorial team Jan 16, 2004

Two custom-designed moulded plastic parts form the mobile base of the new TracVision A5 ultra-low-profile satellite TV antenna.

Sarnatech BNL's partnership with the world's leading provider of mobile satellite communications and TV-based antennas, KVH Industries, goes from strength to strength with the production of two new custom-designed parts.

The moulded plastic parts - a bearing and giant thrust race - form the mobile base of the new TracVision A5 ultra-low-profile satellite TV antenna which is designed specifically for passenger vehicles.

Using KVH's revolutionary phased-array technology, it provides in-motion access to more than 300 live satellite TV and music channels via virtually all in-vehicle passenger entertainment systems in sport utility vehicles, mini-vans and cars.

Having already provided the perfect bearing solution for KVH's successful TracVision L2 and G6 mobile satellite antennas, Sarnatech BNL's expertise was called on once again for the ground-breaking TracVision A5 project when the bushing solution KVH was trialling failed due to high friction problems.

With the overall height of the antenna fixed at just 4.5in, Sarnatech BNL's design team had to come up with an ultrathin bearing in ultraquick time.

But, having worked closely with KVH before, the team understood the application and the potential problems.

The TracVision A5 project had been alive for 2 years, but in just 2 weeks, the bearing design had been approved and the first prototype produced 2 weeks later.

The bearing is very thin - just 0.375in high - with the pitch circle of the raceway designed as large as possible to offer maximum support.

Integrated features include belt drive teeth around the outer edge, brass inserts to fix it to the unit and moulded pads on one side to provide extra stability.

Being plastic, the Sarnatech BNL product is a much lighter weight solution - it is also more cost effective - an equivalent bearing in stainless steel would be many times more expensive.

"When the bushing system we were testing failed, Sarnatech BNL was the first call we placed as we knew they could provide the engineering support that was needed in a very short time period", said Gerry Maynard, Senior Mechanical Engineer at KVH.

"We had a problem and they solved it.

They told us what they could do, delivered what we needed on budget and in time for a successful launch".

As well as a bearing solution, KVH needed to find a way of supporting the perimeter of the 30.5in-wide antenna and asked Sarnatech BNL's design team for ideas.

The result is a giant thrust race with an outside diameter of 25in.

Manufacturing a plastic part of this size causes problems with tooling in terms of the expense due to wasted space in the tool.

The team overcame this by sectionalising the part in order to make it both cost effective and easy to manufacture with each part being moulded in one shot.

The finished part is made up of eight identical sections which fit together effortlessly by way of an integral connection clip design.

KVH is delighted with Sarnatech BNL's solutions for this very high profile project.

"Sarnatech BNL is a valued supplier and contributor to the initial success of our TracVision A5 programme", said Paula Conway, KVH's TracVision A5 Programme Manager.

"Their overall responsiveness to day-to-day changes has resulted in a smooth and timely product launch".