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Black Contracting Cat 555D Skidder

The temptation when you've got a bigger, faster and hungrier machine is to go flat out and increase production. And Warren Black would dearly love to unleash all the awesome potential from his new range-topping Caterpillar 555D grapple skidder. But it would soon eat the guts out of the Herbert Forest, on the north Otago coast, and leave very little wood for the future.

So, in the name of sustainable harvesting, Warren has dialled his working shifts back to four days a week. And even on those days it’s still gentleman’s hours, with the bulk of the Black Contracting crew starting around 7am and gone by 3.30pm. It does, however, mean they can continue to work at a good pace on those four days and enjoy a three-day weekend while the opportunity allows.

“It is what it is,” says Warren, philosophically. “It’s all about sustainability, not over-cutting. At least I know what I am doing for the next 40 years if I stay here!”

He’s grateful that forest owner Blakely Pacific has such a long-term view of its estate and is prepared to work with its harvesting crews to ensure they are not penalised in the name of sustainability.

“They look after us pretty well,” he adds.

There is an opportunity to move into bigger production forests when this block of Radiata Pines is completed and Warren licks his lips with anticipation at the prospect. And looking even further ahead, a lot of Douglas-fir will be reaching harvest age within the decade, which he’d love to be involved in, too.

Taking into account the equipment Warren has at his disposal, his Black Contracting crew would have no trouble shifting up a couple of gears and still have capacity to spare. The skid site is dominated by a Cat 568 and Waratah 625C processor, which needs a constant, high-paced supply of wood that the crew’s previous Cat 545C was only just managing to keep up with.

To get a bigger skidder, Warren could have swapped to a brand with a slightly different shade of yellow, where he would also have got six driving wheels instead of four, but he has Caterpillar blood coursing through his veins and he also knew that another option was on its way, in the shape of a revamped D-series, featuring the 555D as its new flagship.

“I knew that the Cat 555 was coming out a while ago and when we (a group of contractors on a Gough Cat trip) went to the factory I was chasing them about it,” says Warren.

“They sat us down and asked us everything we wanted in a skidder and on my list was ‘hydraulics’, ‘weight’, ‘horsepower’ ‘where the handbrake is’ and the ‘door handles’. And it’s all been fixed, apart from the door handles, which aren’t really an issue, just a pet hate – they use the same door handle on each side so that one locks at the top and the other one locks at the bottom. It’s a pain in the arse so we just keep one door locked all the time.”

Door handles aside, Warren says the new 555D has not only met his expectations since it started with his crew in February, it’s surpassed them.

“It’s been everything, and more, than we expected,” he says. “It’s a real good skidder. Like, we pull 20-tonne drags to the processor. It’s probably not supposed to do that much, but it will. When they say it’s designed to do such-and-such, then I want to take it to its limit.”

That statement is accompanied by a naughty boy grin from Warren, as if he was expecting to be told off, but the sentiment would be familiar to many New Zealand contractors, who are not afraid to work their machinery to obtain maximum bang for bucks. There’s a lot of bang and plenty of bucks involved with the new Cat 555D.

When Warren’s machine arrived, it was the first of this big, new model to go to work in New Zealand.

It doesn’t actually replace the 545, which continues in the new D-series line-up with a number of its own upgrades, as well as a new 535D and 525D. All boast more grunt and improved performances.

Their predecessors, the C-series skidders, have done a sterling job for Caterpillar over the past decade, but the competition has become fierce in recent times, particularly at the top of the range.

The new 555D answers much of the demand from people like Warren for a premium skidder that will tough it out at the top.

It’s got a little bit more of everything when compared to the new 545D and significantly more when set alongside the old 545C.

At 9007mm from blade to grapple, it’s 180mm longer than the 545D, which itself has grown some 800mm over the old 545C. And it’s got the mass, tipping the scales at 21,540kg, making it 350kg heavier than the 545D, which is now a couple of tonnes heavier than the 545C.

With the move to the new 7-litre C7.1 ACERT engine, which has a longer stroke and narrower bore than the old C7, the power stakes have also grown – impressively so in the 555D, now boasting a peak output of 205kW. That’s up 28% against the 163kW in the old 545C (the new 545D now boasts 186kW) and translates to around 20% more power at the rim.

Significantly, the new Cat 555D engine is the first Tier 4 environmentally friendlier power plant to enter service in a forestry machine in New Zealand, requiring the use of AdBlue, like modern trucks and it hasn’t fazed Warren one bit.

“We are adding AdBlue around every two tank fulls or maybe one-and-three-quarters – it’s nothing to worry about,” he says. “We just carry a 20-litre pack and pour around 15 litres in. We have packs on hand for when we refuel, it’s no hassle. You just walk around to fill up the AdBlue while it’s

refuelling and then walk back, no extra time involved.

“It has to go that way, trucks have been doing it for ages.”

The new Tier 4 technology is very dependable, Caterpillar Production Applications Specialist Matt McDonald told NZ Logger in a recent interview, and there are many positives to its introduction, which he explains in the separate article on page 33.

One of the keys to making Tier 4 technology work is in the design of the cooling system, points out Mr McDonald. “To meet higher emissions regulations and the different engine installations we didn’t want to be restricted on our overall cooling package size, so that’s why we went to a cross-flow configuration because we could design it to the specs we wanted, versus designing it to a spec just to sit inside a frame,” he says.

“We reduced the core density, which is a pretty big deal in forestry – previously we were 9 fins per inch and it’s been reduced to 6 fins per inch. That means it is much coarser and has bigger gaps, to allow debris to pass through. Then we also added an oversized hydraulic (auto reverse) fan so it only spins as fast as it needs for maximum efficiency, fuel economy and power to the ground.

“One of the unique features we have with the cooling package is really great service access. We have hinged panels so we can get to all different sides of the cooling cores. We have a ducted shrouding as well that encases the fan and forces all the hot air coming through the cooling system out of the machine, versus allowing it to be blown in and around the engine compartment.

“It keeps the heat out and allows us to compartmentalise the machine. From a debris standpoint, this keeps the machine much cleaner because we’re not sucking in everything from the woods into the engine compartment. That’s important as these machines run in high debris applications and dusty areas, such as light, powdery sand and they’ve had no issues with having to clean out their cooling cores. The temperatures don’t change much during operation, because the hydraulic fan keeps everything running at an optimum level for efficiency, it’s just that we have the capability to control that now and keep it at a good temperature so when it’s cool outside the fan will not spin as fast and it allows the systems to run at the right temperature. And it brings them up to temperature quicker.”

That’s a comfort for Warren, given the extreme weather conditions experienced in the Otago region. He is equally happy that Cat skidders continue to make full use of powershift transmissions, instead of adopting the constantly variable hydrostatic system.

He prefers the more direct drive from a powershift and the fact that it has defined gear ratios. In the 555D, the improvements have seen a six-speed powershift replacing the previous five-speed unit, which is claimed to deliver more evenly distributed changes in the working range – there’s not a huge gap in the ratios to fifth gear as there was before, and the step up to sixth is equally short. In reverse you still have a choice of three gears. There’s also the Electronic Clutch Pressure Control, which helps with smoother, faster and more efficient gear changes. This works nicely with the lock-up torque converter to achieve fast travel speeds (up to 20km/h in top) with less of a fuel penalty.

Interestingly, the torque is reduced through the transmission and drivelines by about 14%, even  though performance is up, which lowers the stress through the powertrain, so there is an expectation of longer life from these components.

When the going gets tough, the 555D can still call on the hydraulically-activated locks on the independent front and rear differentials, which can be engaged on the move, to help retain traction.

Changes to the hydraulic system, which were also on Warren’s wish-list, include a 16% increase in pump output, to 220L/min. The result is faster cycle times and no delays when using a lot of functions together. It delivers more lift power in the boom (up by 23%) and the auto-grab has higher pressure, ensuring trees are held tightly in the grapple, which is especially important given the big increase in the grapple size and the amount it can hold.

Boasting a capacity of 2.04m2, the grapple is 33% bigger than on the old 545C and the boom has been enlarged and reinforced to cope with the extra weight and forces. In fact, the whole structure of the new 555D has undergone a heavy-duty make-over, from the frame to the centre pivot and blade mountings, as well as the boom. Bottom guards over the axles are bigger, too, just in case the 611mm ground clearance isn’t enough to clear an object.

A late addition specified by Warren is a lightweight retrieval winch, tucked in between the arch/boom and cab, to drag trees off the slope when required (line capacity is 59m of ¾” rope).

Atop that big frame is an all-new cab, with improved vision, particularly to the rear, where it is now shaped instead of being squared off.

Warren likes the new cab, adding that there is no pre cleaner on the bonnet to spoil forward vision, either. It’s a bitof a climb to get up there, but once in the cab it feels roomier, especially with the previous bulky dashboard replaced by a large, flat digital display that now sits directly under the windscreen instead of sticking out towards the operator.

Deep windows stretching down to the floor on either side of the steering column allow the operator a much clearer view of the front wheels.

The seat still swivels 30-degrees to the right, so the operator doesn’t have to crane his neck too far when looking back to grab the trees. The seat itself is much improved, with a higher backrest and more lateral support, plus it now incorporates the joystick controls for the grapple at the end of the right armrest. You can read more about the controls and the whole operation in Stan Barlow’s Iron Test column.

One thing that both Warren and his brother Arden, who’s the regular operator, both agree on is how quiet the cabin is, compared to their old skidder. That’s because it is pressurised when all the windows and doors are closed and it also benefits from better soundproofing. It’s not only quiet inside, but outside, too.

“That’s the biggest thing we’ve had to get our heads around,” Warren says. “You can’t hear it coming when the Waratah’s going, but we could always hear the 545, especially when it was running on chains. We haven’t had to put this on chains yet, only because we are doing a lot of downhill pulling at the moment and it’s not that wet. Chains dig the tracks up, so we’d rather keep it on the tyres.”

Servicing is a lot easier with the new D-series skidders, with access to all main areas from the ground, mostly through hinged side panels, including the AdBlue fill point. The hydraulics and transmission can be accessed by tilting the cab.

With the sun now up over the horizon it’s time to experience some skidder action. Arden has taken a break from running up the hill to bring down trees from an area some 800 metres away, so Stan is given his riding instructions for the test drive and gets into it straight away – the controls are very intuitive, so the briefing is over quickly.

That gives me a chance to talk to Arden about his experiences with the new skidder, compared to the 545C. He’s been working with his brother nearly four years in this current stint, having first joined him in Southland 20-something years ago, when Warren started out, before taking a break to go roofing and most of Arden’s time is spent in the cab of the skidder.

“There’s way more power in this, compared to the 545C,” he says as we watch Stan race up the hill. “You can carry bigger loads – I was bringing in eight or nine trees in each drag yesterday, though you don’t really want to overload it, especially when you get on the soft clays. It wants to do it, but there’s no point struggling and it doesn’t like turning in those conditions with a lot of weight on the back. You’ll just end up going slower.

“It’s definitely quicker with that extra gear in the transmission. The return speeds are way faster. You can hold the gears coming down the hill with big loads in the grapple – I try not to go over 2000 revs. I use all the gears, it’s got them, so why not. And you can go back up a slight grade like this one in fifth or even sixth gear when empty, whereas in the 545C you’d be in third.

“I guess that’s why we use less fuel because we’re not working the engine so hard.”

Another reason is the 35.5 larger wheels and tyres that are optional to the standard 30.5s, so the skidder covers more ground for the same effort. On this particular job, the 555D only needs to be refuelled once every two days, instead of almost daily with the 545C, but that will change on tougher terrain.

Arden says it feels similar to drive as the old 545C, although it’s obviously more responsive to the controls and he much prefers the grapple joystick being attached to the seat, instead of on a panel to the side. The overall view to the outside and the extra seat comfort also get big ticks.

Stan returns with his first load and uses the blade to push the half-dozen big trees closer to the processor without breaking into a sweat – Warren had the blade extended a good 10cm on either side, along with building up the top of the blade, to improve pushing capability. Then it’s back up the hill for another load, with Warren and myself following on foot.

Warren usually arrives a little earlier at the site each day so he can take a few turns in the new skidder himself to help Dan in the processor cut enough logs for the early trucks. Even though the harvesting numbers are restrained, Black Contracting still manages to ship out 14 truck loads a day. Nice going.

Much of that is down to the increased appetite of the skidder. Warren says: “The increased power in the 555D is very noticeable, when compared to the old 545C and the hydraulic speed is a lot faster.”

Warren points out another bonus, which has more to do with the increased size of the 555D on these hilly blocks: “It’s good on gradients, you’ve got a bit of extra length and extra width and a lot more of your weight is down lower, compared to the older skidders. That makes it more stable, as well as helping to get the extra power and traction onto the ground.”

When all those attributes are combined with the larger grapple, which can fit more logs, he says it “makes a big difference to productivity”.

Up at the top of the hill we’re able to witness just how many trees that big new grapple can grab in one go, as Stan backs the 555D into a roadside stack for his third load in just halfan- hour. Good articulation from the centre joint makes such manoeuvres much easier, given the extra overall length of the machine and its longer wheelbase, especially when trying to make sure the trees are well supported in the grapple. The dual function boom has plenty of grunt from the four pistons to raise the grapple and trees off the ground, almost to the top of the tyres – the higher the better, so the trees aren’t dragging on the dirt too much.

Stan makes good use of the sturdy frame that supports the boom in order to reverse the butts securely into the grapple, before taking off again with another seven-to-eight in tow, which it seems to cope with easily.

The comments about quietness come to mind as the Cat drives past. Even though it’s just a few metres away, there’s probably more noise coming from the trees dragging on the ground than from the machine itself.

It’s now fully daylight, but one of the items we’d been  discussing when Stan and I arrived earlier in the dark was the good lighting on all of Black Contracting’s machines, including the 555D, which lit up the area around each piece of equipment very effectively, adding to the safety. The 555D’s cab has 12 lights festooned around the top of the cab.

“I’ve spent about $3000 on each machine putting LED lights on them,” says Warren. “It’s important to have good lighting working those early hours in the morning. Makes a big difference to the operator, cuts down the fatigue and stress when you can see everything.”

It’s the sort of investment that pays off in many ways. Just like buying machines such as the Cat 555D. As Stan continues his test, it’s easy to see how the new 555D is helping Black Contracting churn out so many truck loads each day so easily. Imagine what could be achieved if it was let off the leash.