Hauling gross combination masses (GCM) of up to 240 tonnes up steep inclines requires axles and drivelines of Herculean proportions.
Under these conditions standard heavy-duty truck axles simply won’t cut the mustard and it’s necessary to employ hub-reduction units which feature a planetary gear set at each wheel end that significantly multiplies the torque delivered to the wheels by increasing the final drive ratio.
As a leader in the truck axle manufacturing sphere, Meritor is constantly developing and re-engineering its products to meet the ever-increasing demands of truck operators, particularly those at the ultra-heavy end of the heavy haulage spectrum.
One such operator is Goldsprings Heavy Haulage, a company based at Rutherford in the NSW Hunter Valley that has been in operation for more than 25 years.
The company’s Director, Mark Goldspring, explains that he was looking for a hub-reduction axle that would be more efficient at highway speeds while still providing the low-end grunt necessary for steep climbs at maximum GCM.
“We wanted to be able to maintain a higher road speed to enhance suitability for our application which involves moving oversize and ultra-heavy equipment all over Australia,” Mark says. “After looking into the new Meritor P610 axle we decided it was the most suitable for our operation.”
Meritor’s hub-reduction axles have been available globally for some time, however the company has now considerably broadened the product’s appeal by re-engineering it to suit the Australian market. The first to capitalise on these improvements has been Kenworth — a popular choice among heavy haulage operators.
According to Mark Goldspring, his 8×4 K200 which was delivered mid-2020 is the fifth Kenworth to be fitted with the P610 hub-reduction axles and while it’s early days and the truck is yet to cover 50,000km, it has shown fine fettle when hauling 100-tonne concrete beams up the mountain from Batemans Bay to Canberra.
Adapting the P610 axle to suit the Kenworth chassis wasn’t a simple exercise for Meritor.
That’s because it required a fabricated axle housing that is manufactured in the USA. In contrast, the P610 used in Volvo trucks has a cast iron housing.
According to Renzo Barone, Meritor’s Australian Territory Manager – Truck, the thick-walled fabricated steel axle housing is extremely strong and allows the suspension brackets to be welded on in different locations to suit a variety of truck brands of North American origin.
“The fabricated housing allows us to weld on localised suspension bracketry which you can’t do with the cast housings that the European trucks utilise,” Renzo says.
Another benefit of the P610, he explains, is that it has five planet gears in the wheel end instead of the usual four which provides additional tooth contact surface area, thus enhancing service life and durability under arduous conditions.
“This is also the reason why the P610 performs very well at highway cruising speeds of up to 100km/h and doesn’t experience high heat build-up under these conditions,” Renzo says.
“The design of the hub cap assembly has ample room to allow a good flow of oil which helps dissipate the heat.”
The hub-reduction ratio of the P610 is 3.46:1 and there is a broad spread of differential ratios available starting at 1:1 which provides a 3.46:1 final drive ratio through to7.20:1.
There are, in fact, a total of ten final drive ratio options encompassing 3.46, 3.6, 3.77, 4.12, 4.57, 4.67, 5.4, 5.47, 6.2, and 7.2.
Renzo is keen to point out that the differential carriers used in the P610 hub-reduction axle are common to other drive axles in the Meritor range, meaning that high levels of after-sales support and parts availability are assured.
On that point, Renzo adds that the planetary gear set is readily serviceable with the sun and planet gears being easily and individually replaceable if necessary.
He also adds that there is an array of magnets positioned inside the housing to contain any wear metals away from gear and bearing components.
Goldsprings’ K200 runs a 4.67 ratio which enables a cruising speed of 90km/h at 1,750 engine rpm in top gear. According to Renzo, this is the most popular and ideal ratio in the heavy haulage realm.
The unit also features the ultra heavy-duty Meritor Permalube RPL35 driveline which is a perfect match with the P610 axles in severe-duty applications. The tandem rides on Kenworth Six-Rod mechanical spring suspension.
The twin steer axles are also Meritor items known as MFS-66, featuring a 6.5 tonne rating which enables a combined steer axle mass of 13 tonnes, subject to taper-leaf spring capacity and legal mass requirements.
Goldsprings’ K200 8×4 represents something of an unusual configuration on the east coast, as opposed to the west coast where 8×4 prime movers are quite common.
For Mark Goldspring, it was an ideal way to enable more weight on the steer, with the prime mover featuring an adjustable turntable which can be moved in small increments fore and aft to ensure the optimum weight is exerted on the steer axles.
“The twin steer axles give us an extra four or five tonnes at the front compared with a single steer axle prime mover,” Mark says. “This means sometimes we don’t need to use a dolly which makes it quicker and easier to get into tight locations.”
All up, Mark says he is very pleased with the performance of the Meritor P610 axles to date.
“The axles stood up really well to the high weights and steep climbs out of Batemans Bay and we are looking forward to seeing how they perform on the longer hauls across Australia in mid-summer with big weights,” he says.
“In our heavy haulage operation, I think they are going to be a good thing for us.”