Old Dog, New Trick

It was an ‘old dog, new trick’ type situation when Queensland livestock operator Mark Johnstone was on a bit of an AMT learning curve with his latest truck. The prime mover the Surat-based business runs is a Mack Titan with a 685hp MP10 engine, driving through the M-drive automated manual transmission.

Old Dog, New Trick

Queensland livestock operator Mark Johnstone.

This is not the standard Titan model. Mark has had a 72-inch sleeper fitted to the truck, much bigger than the factory-fitted option. There’s 2,100 litres of painted fuel tanks on the chassis along with 260 litres of Adblue, but under the trailers there’s another 800 litres of fuel in the belly tanks.

Mark’s comment is “you can never get enough horsepower,” but he has found the truck capable of handling the work he does.

“It was a bit of a learning curve on the M-drive AMT,” says Mark. “At first, I just jumped into the truck and went with it. I simply left it in the heavy-duty mode and sometimes used the manual mode. Then after three weeks, I had some trouble coming in from Epsilon Station.

“It had rained out there so we couldn’t use the road. Instead we detoured around through Innamincka, but there’s a big jump-up across there. Most of the fellas will drop their third trailer and then go back down to bring it up afterwards. I thought, if ever there was a chance to try this thing out, it was then, because I had another truck with me who could pull me over if there was a problem.

 

Old Dog, New Trick

 

“There’s probably a kilometre of heavy pulling, then you hit the really steep bit at the top. As I came up to the climb, I hit the button to go into manual. However, when it got up to the top and it started dying, I hit the button to go down a gear and it wouldn’t. So, I had to just sit there and see what it would do. In fact, it hadn’t selected manual at all, it was still in auto.

“On the steep section, with me at around 148 tonnes, it was in fifth and it came back to about 1,050rpm. I thought there was not a chance in the world it would change without stopping. Anyway, just like that, she just changed from fifth to third and when she did, the wheels started spinning. I thought I was going to lose traction, but I just lifted my foot off the accelerator a fraction. Then it just settled down and pulled away.”

Mark learned later the gearbox has an inclinometer, which tells the gearbox what kind of grade it is climbing. Unfortunately, when the prime mover levels off at the top and the AMT thinks it’s on level ground, it can try and change a gear with three trailers still hanging down the hill. The strategy, which Mark learned when he did ask for training, is to select manual at the top of the climb to hold onto the gear until all of the trailers are over the top.

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Author: Tim Giles

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