Neway Tri-Drive with Sisu hub reduction axles: Review

The Sisu axles in this Kenworth C509 originated half a world away in the cool climate of southern Finland, a far cry from where they operate today.

My WA journey begins at MLG's West Kalgoorlie depot. I'd arranged to catch up with owner Murray Leahy to discuss the advantages of specifying the Sisu hub-reduction final-drive axle for his operation.

Out in the heart of the Goldfields, one of Murray's Kenworth C509s is toiling hard in the intense summer heat.

Here today, if you can find a bit of shade anywhere, you'll quickly discover it is a tad over 45 degrees Celsius, or 113 degrees Fahrenheit in the old scale.

However, out on the side of the road, it's even hotter. So much so, I needed gloves to prevent burning my hands on the hot metal arms of my camera tripod. It's undoubtedly a good testament to the durability of the components in this road train combination, which hauls such enormous loads in this intense heat.

An hour or so later, the familiar deep reverberation of a Cummins engine brake signaled the arrival of Greg Loughlin. He was taking me for a run to collect a load of gold ore, so I could see how the Sisu rear axles performed first hand.

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Greg was heading for the Fairylands ore pit; it’s a part of the Lawlers mine project that also comprises the mine sites of Great Eastern, Hidden Secret, Golden Swan and New Holland.

The Lawlers mine is an underground mining operation located on the Norseman/Wiluna Greenstone Belt, approximately 900 kilometres northeast of Perth.

Today the once-bustling settlement of Lawlers is a ghost town, with very little left to mark its existence. The town derived its name from Patrick Lawler, who first discovered gold here in 1892. At one stage, the town's population was over 8000 – the third-largest in the state.

In recent times, though, the Lawlers mine operation has made the most of its abundant mineral reserves with an annual average production of 234,000 ounces of gold. To put that into a dollar value, at the time of writing the price of gold was around $A2300 per ounce, which loosely translates to an annual average turnover of $538m.

Greg swung the C509 around in a wide arc to get his three trailers arranged in a straight line, ready to load at the mine site. A sudden gust of wind swirled a thick blanket of dust over the truck.

"Those wind gusts are common out here," said Greg.

Dust is arguably the worst enemy of internal combustion engines and truck drivers alike. The fine dust particles quickly find their way into air cleaners and, in these conditions and over a relatively short period, can drastically reduce engine efficiency and economy.

When these big 625hp engines are working hard, they can gobble up over 45,000 litres of air per minute. That's as much air as a human breathes in four days.

With its twin raised air-cleaner intakes, Kenworth’s C509 is a great asset to have in these conditions and that’s why Murray Leahy specifies them.

Dust suppression around the mine site and on haul roads is vital for the health and safety of the workers and equipment. However, sourcing the crucial water required for dust suppression can often be as hard as extracting the precious gold ore.

The Lawlers mine, like many WA mining operations, is located in an arid area where the water is limited and the local supply may be of poor quality. Consequently, the mining companies build their storage and treatment plants to conserve local water supplies.

In addition, at most sites like this one, approximately 17 per cent of the water is recycled. However, Greg explained that as much as 70 per cent of the water is recycled at some mine sites.

Nevertheless, my assignment was to investigate the rear axles on this C509 – a heavy-duty Sisu FR3P-48 hub-reduction Tridem.

The main advantage of this type of planetary drive axle set-up in heavy haulage operations is their ability to reduce the burden on driveshafts under extreme loads. Sometimes this style of rear axle is referred to as a double reduction final drive, because it has one reduction in the differential centre and a second reduction out on the wheel hub. Consequently, they're also known as hub reduction axles.

Double reduction axles certainly have superior strength and durability because the gear down occurs in two stages, a tremendous asset when loads are over 200 tonnes or more.

Consequently, with extreme loads, during lift-off as the truck works up through the gears there is a wide fluctuation in torque through the driveline as the engine revs rise and fall. Torque is spread across a greater gear area in double reduction rear axles, significantly reducing the risk of sudden axle failure due to massive reverse torque.

There are three separate oil reservoirs: one around the crown and pinion and one in each wheel hub end. Accordingly, this means that on steep gradients, especially if the vehicle is facing the slope, the oil level remains at a level where it will continue to cool and lubricate bearings and meshing gears.

If there is a downside to hub reduction rear axles, it is that they are not as fuel-friendly as single reduction rear axles.

The Neway AD369/10 Tridem rear suspension is a good match for the Sisu FR3P-48 rear axles and incorporates a non-torque reactive parallelogram suspension geometry. The design of the Neway AD359/10 reduces driveline noise and vibration by maintaining a more constant driveline working angle during axle articulation and high torque input.

Furthermore, it minimises the effects of pinion angle change caused by high torque input that can exceed the maximum recommended driveline working angles, including acceleration with heavy loads and climbing steep grades.

Likewise, the parallelogram geometry reduces chassis frame rise due to suspension wind-up. The suspension assists the driveline in maintaining proper cancellation angles, which promotes extended universal joint life. It is crucial with short inter-axle shafts, such as with tandem and tridem drive-axle configurations.

With the C509 now loaded, Greg climbed back into the air-conditioned cabin, turned the fast idle off and began to fill out his paperwork.

Then it was down to the business side of the job. With a 155.2 tonne payload, the 625hp Cummins under the hood was undoubtedly in for a workout as it sent its torque down the driveline to the Sisu hub reduction axles. The cabin shuddered as the road train lifted off, and another monster load of gold ore rolled out of the mine site.

Engine: Cummins Signature
Power: 625hp (462kW) at 1600rpm
Torque: 2050lb/ft (2779Nm) at 1100rpm
Gearbox: Eaton RTLO22918B 18-speed
Clutch: Eaton 2250ftlb Easy Pedal Advantage
Front axle: Meritor FL941
Front suspension: 8.2T Slipper
Rear axles: SISU FR3P-48
Rear axle Ratio: 4.89
Rear suspension: Neway AD369/10 Tridem
Main driveline: Meritor RPL25
Inter-axle driveline: Meritor RPL20
Electrics: Power distribution box under sleeper
Brakes: WABCO ABS with traction control
Fuel: Alloy 4 x 450lt
Wheels: Ten-stud polished alloy
Bumper: Alloy bullbar
Extras: Twin CR Turbo 2000 air dryer with heater, chassis checker-plate, dolly pull to rear of chassis, freshwater tank