We put the Allison TC10 transmission in a Kenworth T359 from Prix Car vehicle transport through its paces
The fact that some people are more buoyant than others seems completely unfair to me. While some glide through the water with grace and poise, others sink like a stone with bubbles drifting from their ear holes. I unfortunately, fall into the latter category.
As far as I know, I’m the only person that can turn a pool pony into a submarine. Apparently this is down to bone density, so maybe I’ve got the skeleton of a Terminator … or not.
So it’s probably not surprising I’m a little jealous of people who can swim properly.
Watching swimmers glide effortlessly through a pool and tumble turn at the end of the lane makes me green with envy.
Goes swimmingly
This may seem a little bizarre but I was thinking of those swimming pool tumble turns not so long ago while I was driving a Kenworth T359.
Thinking about going for a swim while driving a truck may make perfect sense to me, if nobody else. But this truck is the first in Australia to have been fitted with the Allison TC10 transmission.
The TC10 is a twin countershaft 10-speed transmission that is also equipped with a torque converter. Hence the TC bit in the name.
The theory is that this transmission provides the best of both worlds — the benefits of a torque converter and the efficiency and performance of a countershaft ’box.
That’s about when the swimming pool popped into my mind. Just as someone who knows how to swim kicks off the end of the pool when turning in their lane, the TC10’s torque converter does
a splendid job of giving the rig a good shove in the butt when starting off from a standstill.
Many of us old-school types may envisage a torque converter that keeps spinning on the front of a transmission and draining torque from the engine, Allison’s torque converter locks up virtually straight after launch.
Navistar partnership
Allison buddied up with Navistar in the United States to develop and test the new tranny which can be found behind MaxxForce engines stateside.
It is now an offering in the International ProStar. The idea is that this ’box takes the Allison name out of its vocational and bus heartland and into local and regional distribution roles.
Considering the engine down speeding trends currently underway in the US as OEM’s pursue fuel economy the TC10 should be a good fit.
The American market is rapidly embracing lower capacity engines and diff ratios that are so tall they almost defy belief in the Australian context. And incoming greenhouse gas legislation is the driving force behind it.
At this point in time the TC10 is rated to deal with the American national weight limit of 36 tonnes gross.
Which as it happens is working weight of your average Australian car carrier.
Car park hauler
The T359 that graces these pages belongs to PrixCar who run a 160 strong fleet of trucks distributing cars between capital cities and to regional areas.
The little Kenworth is actually based in Adelaide and regularly runs into regional areas as well as to Melbourne.
As the 359 was barely three weeks old, PrixCar national equipment manager Kevin Rodda wasn’t able to give me any definite fuel figures but did go as far to say that anecdotally the TC10-equipped Kenworth was already saving fuel.
Some American operators are claiming a 5 per cent improvement in fuel economy since adopting the Ally self-shifter.
A car park is not the most aerodynamic combination at the best of times, loaded or empty, and while fuel economy may not be the target; it’s nice if you can get it.
For a company, such as PrixCar that uses 15 million litres of diesel a year even a 1 per cent saving is a huge gain in profit.
A different direction
The motivation to give the transmission a go came after a couple of clutch failures with the fleet’s current transmission choice.
Initially, the company considered using the heavy-duty full-auto 4500 RDS Allison transmission but given the amount of highway running involved it was decided to give the TC10 a whirl.
“We started talking among ourselves with the workshop guys,” Rodda says.
“And we thought why don’t we try an Allison.”
Allison’s Robert Cavagnino joins in saying: “We quickly realised that the transmission we should be centring on and looking at is the TC10”.
The T359 only had 15,000km on the clock when we caught up with it and was barely three weeks old. But the curtain lowering on Australian auto manufacturing over the next 18 months also played a part in the transmission choice for PrixCar.
Changing roles
As the Australian automotive industry moves towards an import-only model, many of the company’s trucks will spend time in metro traffic running to portsand to holding yards as well as line-haul duties.
“The TC10 is the best of both worlds, being a line-haul transmission as well as being able to deal with the high stop-start capability of the converter; it seemed like the perfect fit,” Cavagnino says.
Standard spec for the PrixCar fleet is Cummins ISMe5 at 435hp (324.4kW) with an Eaton UltraShift Plus automated manual transmission (AMT) taking care of shuffling the cogs.
However, in this case the TC10 was retrofitted before the T359 went into service.
Another surprising addition to the Kenworth was the extremely tall 3.08 final drive ratio, replacing the factory-fitted 4.33 ratio.
The torque multiplying characteristics of the Allison torque converter means that the Kenny should still leap off the line without bogging down.
Another advantage touted by Allison is that the ’box uses full power gear shifts to keep that tail shaft twisting at its best.
Virtually all AMTs on the market with perhaps the exception of some Euro 6 based dual clutch examples need to break torque when shifting up or down a ratio or two.
This truck has two regular drivers who rotate through it.
Adelaide-based driver Martin Eales has had three weeks to come to grips with the new transmission.
“I do find the truck gets going faster and smoother with this ’box,” Eales says.
“And it works well with the Jake brake when coming down a decent hill.”
Behind the wheel
So I climbed behind the wheel of the loaded Kenny to have a go at this tranny myself.
Our short route was going to take in plenty of metro traffic roundabouts and intersections.
I was interested to see if the TC10 would live up to the hype.
The Allison selector pad installs neatly in the 359’s cockpit and looks pretty much like any other Allison selector.
But ‘D’ for drive and a push of the go pedal saw the little car park move off strongly and smoothly.
Some of that Allison driveline sound is still there but I was too busy noting just how strongly the truck pulled away.
The ’box has a relatively tall first gear ratio of 7.4:1 and with the tall rear-end expected there to be a bit of a shudder as the truck pulled away.
Instead, the Kenworth just hauled.
Intersecting shifts
The first intersection was interesting as it was an uncontrolled right-hand turn without traffic lights.
The temptation here is to plant the foot to get the truck out onto the road as quick as possible.
Every day, somewhere in the world at any given moment, there are truck drivers swearing at their AMT-equipped steed as they try to clear an intersection in a hurry.
The more you press the go pedal, the more gears an AMT will use to accelerate and hold onto them for longer.
The cab starts to lift as the tacho climbs and the engine wails but you are actually going nowhere fast. Instinct wants you to go faster; the result is actually slower.
A change in camber mid-intersection can also confuse an AMT. The truck all of
a sudden thinks it’s climbing a hill and grabs a lower gear, then thinks it’s going down a hill and changes up a gear. In the meantime, you are halfway through the intersection raising the ire of your fellow road users as the AMT ’box jumps up and down gears.
Not so with the Allison.
I was wanted to see how the TC10 would behave and it was impressive.
The acceleration rate management of the ’box keeps the launch smooth even if you do floor the right pedal.
Full power shifts also mean that there’s no pause as the Kenworth hauls through the gears.
The change in road camber didn’t faze the Allison either as it dragged the loaded trailer through the intersection.
There is a ‘Performance’ mode to change the shift pattern if more gears and more rpm are needed but I left this alone.
I wanted to see how the tranny would behave just left alone with no manual intervention.
Neutral Idle
The Allison neutralises at idle but pops straight back into gear with almost instantaneously when throttle is applied.
But where I was really impressed was when rolling through an intersection, like a roundabout.
A decent driver is always going to anticipate the traffic ahead and keep the rig rolling if possible.
It’s always harder and slower to get a loaded truck rolling again from a dead stop, especially at a busy roundabout where you have to pick a gap and go for it.
With the tranny neutralised and the wheels turning slowly, I
approached one roundabout until a gap presented itself.
I hit the go pedal and the TC10 picked the right gear straight away.
The 359 was given a shove into the intersection and away we went with no indecision on the ‘box’s part.
It may lack the quiet precision of a European AMT in operation but on the other hand it doesn’t have a clutch to engage or to maintain.
Gear ratios in top box are reasonably close together yet it is essentially an overdrive ‘box with ninth gear having a direct 1:1 ratio.
There’s only a 17 per cent jump to the 10th gear overdrive and its 0.86:1 ratio.
For the sake of the exercise I decided to be very politically incorrect and see what effect the Jake brake had on the Allison.
From 10th the TC10 will drop two gears at a time under engine braking and the Cummins seems to talk to the Allison just fine to bring speed down smoothly.
Gear changes can also be pre-selected by the driver if needed.
I tried on a few occasions to confuse the Allison yet it proved to be very hard to unsettle, even clumsy footwork failed to get any indecision from the tranny.
Impressive performer
The TC10 is an impressive performer that works well behind the Cummins ISM.
However I reckon it would really shine behind an engine with a lower flatter torque curve such as Paccar’s MX-13.
Which is no surprise given the TC10 was developed behind Navistar’s MaxxForce 13 engine in the US which also has similar torque characteristics to the MX and shares its Euro heritage.
Daimler’s Heavy-Duty Engine Platform (HDEP) engine family would also be a nice fit, though with the company moving towards an integrated driveline in its home market Freightliner offerings, I’m not sure that there’d be a lot of interest from that quarter.
Clearly this isn’t a line-haul transmission, especially in a market with high gross weights such as ours.
At the moment, the TC10 is still at the 36,290kg GCM mark though Allison is working on lifting the GCM of the cog box.
If it could be rated to 50-tonnes, for example, I reckon it would excel in tipper and dog roles and even pocket B-double roles where heavy traffic is a given and low speed tractability is needed.
It is, however, a premium product and priced accordingly, which may affect operator acceptance to a degree.
It remains to be seen whether the TC10 will sink or swim on the Australian market; however in the right application I reckon it deserves a closer look.