John Fraser has been running a business fuel hauling in the Northern Territory for over a decade. His transport operation has been working for IOR Petroleum for 12 years, starting with one truck and then going to two trailers.
The operation currently run two trucks and has another undergoing restoration. There are two trucks on fuel full time, plus one subcontractor. The trucks include a 700hp Volvo rigid with three trailers, and a Kenworth K200 tri-axle prime mover pulling three trailers.
It has a pusher axle so it gives the truck full loading on the drive. With the pusher John can get 22.5 tonnes on the drives in the Northern Territory. It’s not as expensive as the tri-drive and needs a bit less maintenance.
The tri-drive twin-steer Volvo has a completely Volvo driveline and runs at a GCM of 164 tonnes. The truck is actually rated up to 175 tonnes, but this kind of loading is only achievable if John upgrades the dollies’ suspensions.
Speccing for the Territory
To build a truck for use in the Territory, operators have to ensure durability at very high masses and a high number of kilometres on a lot of substandard roads. The company’s rolling stock uses all tri-axle trailers and all tri-axle dollies.
Trailers use air suspension, while dollies are on steel springs. Steel-sprung dollies are considerably cheaper than their air suspended equivalent and Frasers doesn’t need the extra mass available on air suspension. The set-up John uses is preferred by WA authorities, who seem to think steel suspension does not do as much damage to the road as it is reputed to do.
The Volvo has a 20,000 litre tank over the drive axles, which gives John plenty of traction to pull three trailers. John also prefers the set-up as it ensures he never has to pull a dolly out from under a fully loaded trailer. When delivering to remote cattle properties he often has to leave some of the trailers in a parking bay as he takes a tanker in to unload.
“The twin-steer tridrive is more about practicality for me,” says John. “I can leave the load on the prime mover as the last delivery – I can leave trailers anywhere. Nothing is left on its landing legs while it is loaded. It’s a safety thing for me.
“If there is an issue with this set-up, the second axle on the twin steer is pretty hard on tyres. I never put new tyres on there; I move tyres from the front axle to the second and put new on the front. It gets ribs across the tyres, especially on the passenger side.”
The drives’ tyres are rotated after 50,000km from the front to the centre or rear axle. The front drive gets more traction and, therefore, more wear. By the second rotation the tyres are well worn and all replaced.
After some issues with synthetic oil in the diffs, John has reverted to mineral oil. With the front drive axle taking the most punishment, the internal temperatures can get pretty high, especially when combined with high ambient temperatures out on the road.
Running at 92km/h
John runs the trucks at around 92km/h as a company policy. Running at higher speeds tends to be detrimental to longevity of items such as diffs, when temperatures start to rise. The Volvo uses double-reduction diffs and John has had no problems with them, although others in the Territory have.
Diff ratios are also an important component in speccing for the conditions. John has moved from a 3.93:1 ratio to the current truck’s 4.11:1 option. If the ratio were any shorter, the engine would be spending too much time at high rpm levels, creating different overheating issues. The gearbox in the Volvo is an I-shift, pulling 164 tonnes GCM on a regular basis, without any major issues.
“We are stopping and starting at seven sets of traffic lights in Darwin and then there’s a pretty big jump-up between here and Darwin, when loaded,” says John. “We get down to 17km/h on the hill and I have never had a problem with my low gears, but I think they could use a couple more gears, at the top of the box.
“At 92km/h the engine is at 1,550 rpm, right where the power and torque curves meet. The Volvo will still pull well down to 1,000rpm. If I could just get a couple of half-gear splits at the top of the box, I could hold onto the gears a bit better at the start of a climb. If the split were just 250rpm it would be easier to go up and down gears.
“With three loaded trailers on, I will go to manual on a climb, because the Volvo auto is very slow to change from high range to low range, from seventh to sixth. So I make that change earlier, otherwise it will go from seven straight to five. It’s more gentle on the drive line to force it to go to sixth.”