Paul Matthei speaks with Wickham Freightlines Workshop Manager, Steve Lord, about a technical solution the company has developed to significantly improve the ride in its K200 prime movers and asks the question, is this the cure for the ‘K-Series Back’?
Kenworth’s immensely popular K-series has been a stalwart of the cab-over class for over half a century, and for good reason. Its propensity for reliability and longevity has enabled a multitude of operators to make a decent profit using it as a tool of the trade. The formula is simple, literally, in that Kenworth has stuck with a tried-and-true cab structure that has been gradually evolved rather than radically changed over the years.
The biggest change in the model’s history occurred when the K108 morphed into the K200 just over a decade ago. Kenworth engineers put a massive effort into improving cab ergonomics for the driver including raising the cab and fashioning a flat floor between the seats for easier bunk access and a safer, more user-friendly set of steps and side catwalk for improved cab entry and egress.
However, they stopped short of fully addressing the K-series Achilles Heel, which is ride quality. Sure, various measures such as parabolic front springs have been added which have made a dramatic improvement over earlier models. But the fact remains that the K-series ‘kick in the back’ is still evident on rough roads, of which, Australia has aplenty.
As a loyal Kenworth customer over five decades, Wickham Freightlines knows as well as any this shortcoming of the K200. But rather than simply accepting the fact, the company decided to design and build its own solution in the form of an airbag cab suspension system.
Interestingly, in addition to a kaleidoscope of Kenworths, the company also runs a smattering of Scanias which are widely regarded as among the most comfortable prime movers in the business.
According to Workshop Manager, Steve Lord, the goal was to replicate, as near as possible, the ride quality of the Scania in the K200 by installing a two-bag rear-of-cab air suspension system.
“Any cab-over Kenworth will whack you in the back on lumpy roads, so we wanted to design a cab suspension system to take that characteristic kick right out of them,” says Steve.
“We used as many Kenworth components as possible, including airbags, shocks and ride-height valves, so that replacement parts could be easily purchased from Brown and Hurley or Gilbert and Roach.”
Steve says the company has a number of talented fabricators who are able to construct just about anything, so the challenge of designing and building the necessary infrastructure for the cab suspension was met with relish by them.
Upon completion of the first iteration, the team installed an accelerometer to test its effectiveness and compared this with the results from one of the company’s Scanias.
“The results were actually quite similar, we were very happy with that,” Steve says, adding that the original K200 cab suspension project was started in 2018 after the company’s Operations Director Graham Keogh suggested he wouldn’t mind seeing some form of cab suspension on the K200s.
“He mentioned this just before he went on a trip with Kenworth to the USA,” says Steve. “So being a bit of a thinker myself and having been in the game a long time, it started me thinking about how we could execute this and everything sort of snowballed from there.”
