REVIEW: Cat 627H scraper
Cat has simplified tractor scraper operation with the introduction of Sequence Assist and Load Assist on its H-series scrapers. Geoff Ashcroft reports from the cab of 627H.
Cat's latest generation has changed the way tractor-scrapers look, run and ride, while putting operator comfort and convenience at the top of the list. Models now get increased power and capacity, plus new structures, electronic controls and an ergonomic cab design – all geared towards moving material at the lowest cost per tonne.
The H-series line-up includes the single engined 621H open bowl and 623H elevator models, plus the twin-engined open bowl 627H. Where push-pull configuration has previously been the domain of twin-engined models, it can now be specified on the 621H, avoiding the need for a dozer to push-load.
Larger 637 and 657 models are yet to be upgraded.
CAT 627H (H-SERIES) SCRAPER POWER
Our test machine is the twin-engine 627H, which gets a more powerful engine in the tractor, and a more powerful engine in the scraper. Up front, the Cat C13 now produces 407hp, an increase of 18% on the G-series.
Bringing up the rear, the scraper’s C9.3 delivers 290hp, representing 19% more power than its predecessor. And with a new torque converter coupled to the scraper engine, this beast can put more power to the ground.
New software delivers a much more integrated performance between engine and transmission. The tractor’s eight-speed planetary powershift transmission benefits from new controls and software to manage torque converter and transmission operation, resulting in smoother operation to extend component life.
Performance on grades and coming out of the cut is said to be noticeably better according to Cat and on flatter hauls, shift points are now optimised rather than always being at maximum power, giving a balance between fuel economy and performance.
CAT 627H (H-SERIES) SCRAPER MAIN FEATURES
Complimenting the new power train and higher capacity are wet disc service brakes that are similar to the firm’s off-highway truck brakes and deliver predictable and durable stopping power. The H-series tractor scrapers also get an engine compression retardation system to replace the hydraulic retarder.
This machine is now much more aesthetically pleasing, with generous use of plastics for the fuel tank and mudguards, while the tractor’s upper frame is much more rounded to help the machine to flow through deep cuts.
While the machines backbone is unchanged – the gooseneck and articulated frame is said to be good for around 60,000 hours – the cushion hitch now gets a double accumulator system to dampen shock loads.
A low-pressure nitrogen accumulator handles unladen/part load comfort, while the high pressure accumulator softens the ride when fully loaded. Both contribute to greater ride comfort all the time.
There are cameras located around the scraper too; one looks directly at the cutting edge; one gives a view down the right-hand side of the chassis to compliment the wide-angle mirrors, with the third camera providing a view of the rear end, making it very easy to see a dozer when being pushed, or to improve push-pull performance without the need for hand signals.
Banks of grease nipples are grouped at ground level, there is a fast-fill point accessed from ground level to fill the mammoth 1,272 litre fuel tank and the scraper bowl capacity has been tweaked by one cubic metre to improve material flow and boost fill factors.
CAT 627H (H-SERIES) SCRAPER TECH FEATURES
Cat offers three new integrated technologies for the H-series and the tech is aimed at reducing operating costs and simplifying operation. These include Sequence Assist, Load Assist and Cat Grade Control. While the latter two are optional, Sequence Assist is part of the standard specification.
Sequence Assist uses integrated software with position sensing hydraulic cylinders to automate many of the tasks an operator is required to perform when loading, hauling and dumping.
The only potential drawback of this system is that you still need to manually adjust the bowl when going into and during the cut, to determine the fill rate and the depth of cut being made. But this is where the optional Load Assist comes into play, which can automatically load the bowl with the push of a button.
As the machine enters the cut, the operator activates the Load Assist program so the machine then takes over control of the cutting edge height, limiting tyre spin based on integrated sensors and GPS technology, to ensure consistently full bowls without shortening tyre life.
It is an elementary form of traction control, though it does mean that once the Load Assist process has been activated, the operator only needs to make throttle and steering inputs.
Importantly, the combination of Sequence Assist and Load Assist helps to shorten the time it takes to train operators, and should help less experienced operators to become more productive very quickly.
The third integrated technology is Cat Grade Control, which has been engineered to work seamlessly with Sequence Assist and Load Assist. Using satellite positioning technology, the system ensures cut protection by limiting how deep the scraper will cut.
Cat Grade Control is not on our test machine, but is factory fitted and puts the site plan in front of the operator for greater efficiency.
CAT 627H (H-SERIES) SCRAPER OPERATOR COMFORT AND CONTROLS
Operator comfort in this new series has jumped into the 21st century. The cab is no longer a close associate to a medieval torture chamber, but a scraper-specific environment that really does elevate comfort levels. The cab is 21% larger with 28% more glass than its predecessor, making it feel open, modern and better suited to the job.
As part of improving ergonomics, the steering column and pedals now align with the cab’s right-hand A-post. This puts the operator in a much more comfortable driving position when the seat is turned 30 degrees.
A deeper front window is complimented by a generously sized rear window, which makes it very easy and comfortable to look down at the cutting edge without having to book a week’s therapy with a neck and back specialist.
Elsewhere in the cab, the right-hand console neatly groups a camera monitor, banks of switches and main instrument display, still leaving space to install a grade control screen.
Below the console is a panel that houses push buttons for the sequence and load assist functions, adjacent to which is the main joystick. In the interests of operator comfort, the joystick is now aligned with the seat armrest. The seat itself is an all-singing, all-dancing affair that creates yet another Cat acronym – CARMS (Cat Advanced Ride Management System. It is a seat suspension system that dampens vibration and prevents end-stroke shock loads.
There is no denying it is a comfy perch and its development compliments the many other improvements on the H-series to drastically reduce NVH.
CAT 627H (H-SERIES) SCRAPER VISIBILITY AND PERFORMANCE
I climb into the cab, taking full advantage of the optional powered access ladder that tucks into the chassis below the door, soaking up the 627H’s modern, spacious cab environment.
However, I was surprised to see an airline-style lap belt rather than a retractable seat belt fitted to other types of kit, but there is still a need to be held firmly in the seat despite all the improvements to ride quality and comfort.
Grossing nearly 70 tonnes and pushing speeds in excess of 50kph with little more than an air suspension seat, a cushion hitch and large tyres for suspension, you’ll be glad to fasten such a decent means of restraint.
Keeping an eye on the instruments, I turn the ignition key and fire the front engine. I push the engine start button to fire the scraper engine and without smoke from its exhaust stack, I’m relying on the rev counter’s display.
I raise the bowl, release the electric parking brake and slot the transmission into D before balancing both throttles with my right foot and heading into the dirt.
The offset controls and a 30-degree spin on the seat means I’m surprisingly comfortable, effortlessly glancing forwards and backwards. It is a much more relaxed working environment.
Not only does the cab offer some decent visibility for a tractor scraper, but it also has an impressively low in-cab noise level too.
A crash-course on the multi-function joystick brings my previous experience flooding back. It opens and closes the front apron to manage soil flow into the bowl; it raises and lowers the cutting edge and affords progressive control of the ejector plate for unloading.
There are thumb-operated buttons on the face of the joystick that are needed to hold the transmission in gear, with the second button switching the cushion hitch on/off.
There are two additional yellow buttons tucked almost under the joystick, but easily reached using my thumb. They control the sequence and load assist functions.
I feel the pressure of extreme multi-tasking and after making a few cuts operating the scraper manually, I’m anxious to try the automated functions to see just how much simpler the 627H could be. A sequence has already been loaded into the machine and it just needs activating with the yellow button nearest to the joystick.
This sets the scraper as ‘ready to load’ and the bowl height, apron height, cushion hitch lock and transmission hold are all engaged. I play with the throttles and gently lower the cutting edge to fill the bowl.
As the bowl nears its capacity, I push the button a second time to activate ‘ready to haul’. The sequence raises the bowl, lowers the apron unlocks the cushion hitch and disengages the transmission hold.
I turn the 627H out of the cut and head for the unloading area. A third push of the same button activates ‘ready to dump’ and this repositions the bowl height, sets the apron height and moves the ejector plate forward.
Once emptied, a final push selects ‘ready to return’ which tweaks the bowl height, closes the apron and resets the ejector to the back of the bowl.
As I point the 627H towards the cut, I only need to tap the button again as I enter the cut, to start the sequence all over again.
Every stage of the sequence is shown with LED lights on the push-button pad, illustrating just where you are within the sequence. It is a brilliantly simplistic set of functions that streamlines operation. But the best is yet to come.
With sequence assist at its ‘ready to load’ stage, I push the yellow button to its left and commence the Load Assist program. I no longer need to adjust the cutting height in work, as the GPS takes over to limit tyre spin while making the most of the bowl’s fill factor. I just steer and throttle the 627H.
I can’t see the tyres to know if there is spin or not, but progress through the cut now feels much smoother, more progressive and more capable. It feels as though the 627H is spending less time in the cut, while achieving a greater fill capacity. And each time I return to the cut, these automated sequences deliver a level of repeatable accuracy that even the most experienced operators will struggle to maintain on a daily basis.
And the reduction in tyre wear and their extended tyre life will be impressive.
When the bowl is full, I push the load assist button a second time to switch it off and this simultaneously activates sequence assist in the ‘ready to haul’ mode and makes it easy to pick up the dump and return modes.
Streamlining 14 functions into four successive presses of one button has removed massive amounts of pressure – and focus – from the cab. It still remains a machine that requires a particular level of concentration and a diploma in mechanical sympathy to get the best out of it.
But after my brief spell at the controls, I am left in no doubt that this machine, with its adoption of 21st century technology, is well-placed to extend scraper operation to a far wider group of less experienced operators.
It is by no means a simple machine to operate. But with Sequence Assist it is much easier and far less complex to operate than its predecessor. And the clever integration of Load Assist should comfortably extend its productivity gap over any other muck-shifting system currently available.
CAT 627H (H-SERIES) SCRAPER SPECIFICATIONS
Tractor engine: 407hp C13 Acert 6-cyl
Scraper engine: 290hp C9.3 Acert 6cyl
Tractor power: 407hp @ 1,700rpm
Scraper power: 290hp @ 1,900rpm
Scraper bowl capacity: 18.3 cu m
Rated load: 26,127kg
Gross weight: 68,295kg
Maximum speed: 53.9kph
Fuel tank capacity: 1,272 litres
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