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Product Report: A matter of control

August 06, 2006 |

Learning to proficiently operate a grader is a daunting task, with operators facing as many as 15 control levers and a steering wheel. Add to that the fact these highly prized operators are usually seasoned veterans – and fast approaching retirement age.

It was time, according to Caterpillar, to find ways to get new operators quickly up to speed on these precision machines. And so the company embarked on a design process that became one of the most intensive efforts it has conducted to date.

Operator input, always key during design, became the lynchpin of the M-Series effort. Operators were surveyed, both face to face and over the phone. They viewed early mockups and machine prototypes. At a middle-of-nowhere test site in the Texas desert they got behind the controls and were intensely questioned.

Early in the design process Caterpillar conducted a worldwide survey of 500 operators that asked, “What would you like to see in a motor grader?” In return, the company got a detailed wish list that included increased cab visibility and easier maintenance of the drawbar, moldboard and circle.

Oh, and something else: please give us joystick controls. “We didn’t even have joystick controls listed as an option on the survey,” says Wade Porter, commercial supervisor, motor graders, Caterpillar, “and they were specifically asking for it.”

Would they make the switch?
Cat decided to go with joysticks – without offering conventional levers as a choice – and set up an extensive field test with a prototype design to better understand operators’ likes and dislikes. Based on that one-day experience, would they switch from the old to the new? Cat was delighted with the response. All the operators accepted the joystick controls from a design standpoint and said they wanted Cat to continue developing it. And even given the rough design at such an early stage of development, 50 percent of highly experienced operators said they would be willing to exchange their current controls right away. Another telling point: 100 percent of novice operators and 83 percent of those with limited experience said they would switch.

All this testing led to the creation of three-axis joysticks that feature a logical control pattern. “Operators have memorized the old controls,” Porter says. “With the joysticks, we wanted to make them more intuitive.” The joysticks have full modulation, so the more you move the joystick, the quicker the hydraulic cylinder reacts. (See sidebar below for further information on how the joysticks function.)

A simulating experience
Caterpillar wanted a way for operators to ease into such a radical change, so the company decided to use simulator training modules. Operators sit before a large computer screen and run the joysticks from an actual M-Series seat. “We felt simulator training would be the key to dispelling the fear of joysticks and getting everyone up to speed,” Porter says. To date, more than 350 customers have used the simulators.

But Cat also found operators who were more than willing to make the leap without a lot of time spent on the simulator. Take Gary Longhe, oiling fuel coordinator for Flagstaff County in Alberta, Canada, an operator who tested the M-Series prototype.

Cat first put Longhe on the simulator, which he says interested him for about five minutes. “I wanted to run the real thing,” says the 45-year-old, who describes himself as “basically born on a grader.”

“Like anything new, you have to get used to it, but in no time I was cruising down the road,” reports the veteran.

Longhe, who just trained a new operator, wishes he had had an M-Series machine on hand for the job. “It’s the machine for any new operator to learn on,” he says. “They’d catch on a lot quicker.”

During field tests, Cat partnered with the University of Wisconsin to film operators using both the former controls and the M-Series joysticks. In the resulting motion capture study, researchers discovered a 78 percent reduction in overall movement with the joysticks compared to the H-Series controls. In addition, there was a 50-percent-plus reduction in flexing in certain muscle groups.

Beyond the controls
Joystick controls weren’t the only request Cat acted on – in fact, the seven-model lineup of M-Series graders will have about 35 percent new content. Visibility improved on several fronts, including the use of an anti-glare black surface on the top of the front frame, lift cylinders and engine.

The joysticks also led to visibility improvements since cab width used to be dictated by the width of the bank of control levers. With the joysticks, designers could put in tapered windows, doors and floors and move the cab support posts out of the sight line.

Drawbar wear strips can now be adjusted from the top, a function that required two people with the H-Series. By removing the access plates located on top of the drawbar, a mechanic can maintain the circle by adding shims for wear strip adjustment or by replacing the wear strips when they are worn out. “The name of the game is to keep the drawbar-moldboard-circle area tight,” Porter says.

The moldboard slide rail wear strips are now shimless and bi-directional. The slide rail shoes allow adjustment up and down as well as fore and aft, eliminating moldboard chatter. The adjustment of these two areas has gone from a 136-minute job in the H-Series to a 31-minute task in the M-Series.

Hydraulics take on oomph
The M-Series two-pump, all-wheel-drive system uses dedicated left and right pumps, which allow independent control of hydraulic flow to each front wheel hydrostatic motor and deliver 52 percent more torque than the H-Series.

Through an electronic control module, front wheel speeds are controlled automatically, allowing full torque through the entire turn. The all-wheel-drive system also has a front-wheel-only hydrostatic mode for precise low-speed performance.

In the fall of 2005, Cat started putting what it calls “field follow” pre-production units on jobsites. “By this fall, these machines will have close to 80,000 hours on them,” says Porter. “It’s been Cat’s most aggressive field follow program.” The first production M-Series appear this fall, with the full lineup introduced by July 2007.

Side to side, fore to aft and twist
So exactly how was Cat able to condense all the functions of a grader into two joysticks? Here’s an overview:

Left joystick
Side to side – steering
Twist – articulation
Right yellow button – auto articulation return to center
Top black buttons – wheel lean
Trigger switch – transmission direction
Left yellow buttons (top and bottom) – gear selection
Fore/aft – left blade lift
Detent – left blade float

Right joystick
Fore/aft – right blade lift
Detent – right blade float
Side to side – blade shift left and right
Twist – circle turn
Hat switch (large yellow button) fore/aft – blade tip
Hat switch left/right – drawbar shift
Differential lock/unlock
Electronic throttle resume/decrement

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Product Report: A matter of control