By: Matt Wood

Even though it may not become available here in New Zealand, we thought a look at the engineering prototype, the Cat CT630S, would be of great interest to readers.

A new Cat truck model is on the horizon and will land in Australia in 2014. The CT630 S will be the company's B-double contender.

Cat -CT630S

Though the S model first appeared in public more than 18 months ago at the International Truck, Trailer and Equipment Show (ITTES) in Melbourne and is expected to emerge on the market in the first half of 2014. There are two design certification trucks currently plying the Australian highways and I managed to snaffle one of them for a few days.

These trucks are in the first stage of a four-stage engineering certification process seeing the vehicles' data logged and their performance analysed during the lead up to full production.

The CT630 S is NC2's much-anticipated, bonneted 26m/34 pallet B-double prime mover. The S fills a gap in the current Cat heavy-duty line up and finally gives the company a worthy contender for B-double local and line-haul duties.

The 90,000kg gross combination mass (GCM) CT630 S is really the most Australian of the Cat line up. It does, like the rest of the Cat range, use the Navistar ProStar as a basis, however the S is something a little different — about 80 percent of the design and engineering work has been done in Australia.

Cat -CT630S-3The ProStar cab has been moved forward 225mm and raised 50mm in an effort to reduce the Navistar conventional prime mover's 'bumper to back of cab' (BBC) measurements. The day-cab version will have a BBC of 2855mm, while the extended-cab version will come in with a BBC of 3515mm.

Under the swoopy Cat family bonnet resides the ADR80/03 (Euro 5) compliant C15 ACERT engine. The result is a uniquely Australian truck. The 550hp (410kW), 1850ft/lb (2508Nm) C15 is the source of motorvation for the rest of the 630 range up to the long wheelbase LS. The lower GCM CT610 uses the recently-released 475hp (354kW) CT13 exhaust gas recirculation (EGR) engine for power.


There's no denying the slippery shape of the Cat range and even the infernally ugly party hat serves a valuable purpose in terms of reducing drag and saving fuel. It's light, too. While weights on the S haven't been finalised, it's bound to be not too far from the extended-cab 630's 8200kg tare weight.


This extended-cab S has a pretty low roofline, which also makes for a bit of in-cabin stooping. This evaluation unit is currently in service with Claire Transport, based in Seaford, Victoria, and by the time I clambered aboard it had already notched up 82,000km.

There's an ease to driving the Cat that the whole range shares. The C15 has a way of chugging down and pulling from low rpm easily, which makes for quite a lazy approach to driving, even with the tall 3.9 final-drive ratio.

For a new Euro 5 engine, there's still nothing else on the market I know of these days that quite sounds like the C15 barking in anger through its twin chimneys.


The drooping bonnet, large expanses of glass in the right spots, and big mirrors all contribute towards keeping all corners of the combination in sight. The only drawback of the big mirrors is of course the amount of window space they take up, and you do find yourself looking around themb — a common issue on many other brands as well. The wide cab dimensions and seating position also make it easier to locate yourself in your lane on the road.

Rear suspension

The S model will only be available with the one choice of rear suspension — Hendrickson's Primaax Ex four-bag setup. This Cat has the shortest wheelbase of the model range, so I was expecting a bit of choppiness in the ride. But I did find the roll stiffness of the Primaax suspension gave it quite a bit of lateral kick in the rear end on rough surfaces.Cat -CT630S-4

The light, air-assisted clutch makes for easy gear changes and a few stabs of the brake pedal on the way down kept things nice before heading into town to play with the early-morning traffic. And in the traffic, the CT really shines. Visibility for a bonneted truck is excellent and those curvy edges help keep the furthest extremities of the prime mover in sight.


The set-back steer axle and short wheelbase of the S makes for a very agile combination indeed for a bonneted prime mover. There was no hanging out of the driver's door or standing on fuel tanks to keep the back trailer in sight, as I manoeuvred the B-double combination backwards down the driveway.


A lack of locker boxes was also an issue on this engineering truck. Dirty items, such as gloves and load binder bars, end up on the cabin floor beside the seat for storage. There's nowhere for spare coolant, oil, or tools that can be accessed from outside the truck.

To date, some dealers have had their own local aftermarket solutions for other models in the range, however, word is from NC2 the production S will also be available with locker boxes on the sleeper versions. For my part, after loading a nice heavy mixed-bag load of glues, plasters, and adhesives, it was time to get some rest before heading for home.


The CT630 S will be marching into the market and standing toe to toe against the likes of the Freightliner Coronado 114, the Western Star 4800, Mack Trident, and Kenworth T409SAR among others.

While some competitors may have set forward steer axles for some specialised applications, the Cat will be bringing a light tare weight, an engine without EGR or selective catalytic reduction (SCR) emissions controls, and aerodynamics to the fight. The news that a walk-in integrated sleeper and locker boxes will be available on the production truck will also raise the S models' competitive standing.

Cat -CT630S-2


Considering the tall 3.9:1 final drive that is standard fitment on most Cat trucks, the S did a mighty job of cresting the grade. However its charge was slowed down somewhat by a truck from a certain Swedish brand near the final pinch.

A consequence of the cab becoming more intimate with the engine is the firewall now intrudes quite a way into the cab — this truck had very little left-foot room near the clutch pedal. According to Cat, this will be addressed in production models as a different-shaped bulkhead around the engine is on the way.

The Gramag leather seat fitted to this vehicle was reasonably comfortable, though the padding in the base felt a bit firm for my delicate posterior. The downside of leather trim is that you may lose a couple of layers of skin off the back of your legs when you jump into the driver's seat wearing shorts on a hot sunny day.

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