Cummins and International have been solid partners in the vocational market for years, and the pairing of the 5600i and a 335-hp ISM in this concrete mixer chassis is another good example of the engineering synergies between the two companies.

The 5600i-series chassis is designed for severe-service on/off highway applications like dumps, loggers, and of course mixers. The setback tandem-steer configuration used by Lafarge Canada maximizes front-axle loading capacity, while the Sheppard M100/M80 dual steering boxes make the wheels as easy to turn as my Taurus.

The exact wheel cut depends on the tires and axles used, but International says it’s capable of a 40-degree cut, making it tremendously easy to wheel around a job site — even with the big Bridgestone M844s and the tiny little 20-in. steering wheel.

The 5600i chassis is built with a mixer in mind. Due to the bridge laws in Ontario, there’s not enough room between the transmission and the rear differentials for a rear PTO to drive the barrel. This one has a front-mounted PTO, sitting between the rails of a 27-in frame extension. The rad is mounted high up and out of the way of the PTO driveshaft. The hood tilts forward, but the grille stays behind so it won’t whack the PTO in the open position.

With the hood open, the daily maintenance checks weren’t difficult at all, but a bigger guy might have a little difficulty wedging himself in between the large tires and the frame.

The rest of the chassis, I have to say, was open and easy to access, making for an easier job for the shop crew. Naturally, I stopped short of actually attempting a brake adjustment or an oil change, but visually there didn’t appear to be any major issues down below.

I confess to being pleasantly surprised by the driver’s work environment. Not only was the cab much the same as the Class 8 highway trucks, it was nearly as well appointed. It’s even equipped with an auxiliary brake valve — the guys call it a ‘spike’. In this case, it’s connected to the drive wheels only, and helps the driver control the vehicle speed while pouring.

The EatonFuller RTO(F)-14909ALL 11-speed features a 26.08:1 reduction in low-low gear, and a 20.85:1 reduction in low reverse. And even with 4.89:1 rears, at times it’s still a little fast.

Driver Doug Field, having 37 years in the concrete business, says it’s one of the better trucks he’s driven at Lafarge.

Cummins Power:

This chassis is equipped with a Cummins ISM 350V engine rated at 335 hp at 2,100 rpm. The brochure says it’ll produce 1,350 or 1,450 lb ft of torque — the line sheet didn’t specify. For Lafarge’s application, it’s ideal. The 335 ponies were more than enough to keep the truck pulling at its loaded weight of 79,500 lb.

At 11 litres, the ISM isn’t a big engine by any means, though it delivers admirably in this application. There was, however, a lot of fan-on time involved in the daily routine. Immediately after loading, the driver spins the mixer up to 13-14 rpm for about 10 minutes. That requires some flat-out time from the ISM, and of course the fan runs flat out too. It’s a big, aggressive 10-blade job mounted behind a 941 sq-in rad. There’s no mistaking when it’s on.

Cummins says the 2002 EPA emissions standards requiring 10-to-15 percent blend of cooled exhaust gas recirculation adds considerably to the workload of the cooling system. The ISM, by the way, is fully EPA certified. It does not rely on emissions credits to attain certification.

In terms of pull, the ISM mated to the drivetrain outlined above would be hard to beat. Concrete mixers do not run highway gears, so operating rpm tends to be high. Field ran the engine upwards of 1,700-1,800 rpm all the time, even when shifting. When I got behind the wheel, using my highway-driver sensibilities, I didn’t fare as well as Field.

Especially when the fan cut in, I found it was like throwing on a Jake. It really grabbed at the revs, and more than once I got caught mid-shift by a fan engagement. Needless to say that had me scrambling to stuff it back into gear.

In addition, I could really feel the engine working through its power curve, and noticed a pronounced surge in power as the revs passed through 1,400 — where the full 335 hp comes on. That too, made for a few difficult shifts. So, like most freshly chastened know-it-alls, I deferred to Field’s way of driving the engine and it worked like a dream. Never mind the engineers, ask a guy who does it for a living.

Overall impressions of the truck and engine combination are darned good. Despite the fan-on time, the engine was pretty quiet. It certainly pulled its weight on the job, what with turning the drum and moving the truck down the road. There’s no vibration to speak of, as the photo of the cab interior clearly shows. The chap on the ground spreading the concrete can be easily seen in the mirror. The cab of the truck is a step up from older International models, which tended to be a little sparse. And in terms of maneuverability and visibility, high marks there too, which is critical in some places.