Finding the elusive creature

In Short Story May 2021, May 20217 MinutesBy Dave McCoidJune 28, 2021

Extracting log trucks from much of the nation’s forested areas in a manner not traumatic to either man or machine has always been a challenge. As we’re all well aware, New Zealand’s a mountainous country. And as payload size increased exponentially from the early 1970s, so did the level of difficulty encountered when exiting the bush, especially as shorter cut logs won increasing favour over the once-dominant long wood.

Before the 1987 increase in GCM to 44 tonnes for permitted trucks, the 6×4 configuration reigned supreme. However, the new regs showed an obvious payload favouritism for a 4-axle configuration truck and therein lay a problem for our log hauliers. Second-steer axles lift the weight off drive wheels, and lifting the weight off drive wheels is an issue in the bush.

When forests such as the Coromandel Peninsula’s rugged Whangapoua Plantation came on stream for the first time in 1992, traditional 8x4s (tandem steel/ double drive), bailey bridge combinations (a long-log semi) and B-trains were prohibited by the forest company Ernslaw One before operations started, due to issues those configurations were known to have in such environments.

Situations like this led to the rise of tri-drives. Operators could at last cash in on the advantages of the 4-axle truck in terms of payload, and leaving the forest boundaries was essentially no longer a problem… well, sort of. There were three main ‘cons’ with the tri-drives in their short reign. Firstly, they were heavier. Secondly, they had more moving bits; but their big downer was a reluctance to go where you pointed them, especially in wet conditions.

The concept that changed the trucking world in the early 1990s. ‘What goes down, can go back up, and visa-versa’. (Right) The in-cab controller: easy to use in a busy office.

Engaging traction aids or loading long wood also contributed to rising in-cab excitement when attempting to manage directional control. In the event all three of the above factors aligned – rain, driveline locking, and load type – it’s safe to say the steering wheel was often about as much use as a pruning saw at the Stihl timber sports. In short, with tri-drives, we’d progressed but hadn’t solved the issue. Back to the drawing board.

The pressures we ran in drive tyres had always been a case of ‘best compromise across the breadth of the vehicle’s workflow’. Lowering pressure to increase the footprint and grip was well known, and automated systems for doing just that had been used in the military since early World War II.

In one of the best examples of necessity being the mother of all invention, the development of a commercially viable central inflation system in the mid-1990s changed the face of truck operation, log trucking especially. Key to its affordability was the design, external hoses delivering air to an ingenious hub-mounted, sealed, rotating union, with no invasive requirement to the mechanics of the inner hub and axle assemblies. Almost overnight, the 8×4 tandem steer/double drive, as we know and love it, became a viable proposition in the bush, a configuration with which you could now load, steer, and exit the narrow, steep, winding trails.

Like anything, there were early teething and lessons learnt. Still, the advantages far outweighed the initial niggles, and it didn’t take long for operators in other disciplines to see the benefits. Stock cartage, road building, mining, lines maintenance, heavy haulage – all are disciplines where CTI has found a welcome home.

In 2021, CTI systems are as reliable as any component on a truck, and Bigfoot Central Tyre Inflation Systems based in Rotorua is one of the industry’s most respected suppliers. Since fitting its first system to an LW Kenworth belonging to Fearon Logging from Masterton in 1994, Bigfoot’s has been a story of continuous development. It was the first and remains the only CTI manufacturer in New Zealand to produce its own sealed rotating mechanical union. It was also the first to introduce a GPS speed signal taken from the CTI system.

In 2016, Bigfoot was bought from original owners Neil and Maree Wylie by Neil’s brother, Graham. Manufacturing for both local and export markets, Bigfoot produces a range of advanced products. These include multi-zone CTI systems that allow different regions of a combination – steering, drive, and trailer – to be managed from a single control unit, and low- height mechanical unions that allow fitment to hub reduction axles.

All manufacture and R&D is done in the company’s Rotorua base by a team dedicated to easing the burden on operators who need to extract increasingly valuable assets from difficult terrain. That dedication to our industry has been recognised, with Bigfoot winning the 2015 Westpac Rotorua Business Excellence Award. In 2017, a study on the benefits of Bigfoot’s CTI systems, accompanied by an international literature review, was undertaken by Dr Glenn Murphy.

“We are a small company with an ever-increasing footprint,” says Graham. “Central tyre inflation is all that we do, and we are really focussed on achieving the best possible outcome for our customers and industry alike. Our system is evolving to take advantage of the latest technology while maintaining our inherent Bigfoot practicality and reliability, which is second to none.”

Bigfoot is another superb example of a local business that forms part of the culture and modern history of the industry it serves.