When you think of revolution you think of Fidel Castro, not Caterpillar, right? Well, grab your boots and hold your breath because they’re playing a new game in Peoria and they’re calling it “revolutionary motor grader.”

Really.

And it just may turn out to be all of that.

Just as Cat’s top-selling H-series motor graders seemed vulnerable to more technologically advanced new generations from Volvo and John Deere, the company has unveiled a new generation of motor graders that just may take the entire category in a new direction.

The new M-series sports a long list of new features, ranging from cutting edge innovations to catch-up technology. But what really sets the M-series apart — and what may make it a truly revolutionary line — is its joystick control system. The M-series graders are the first to adopt total joystick controls. In place of the traditional row of eight or more levers and a steering wheel, the new graders use two joysticks to control all blade functions as well as the steering.

The effect is dramatic. With the bank of levers and steering wheel gone, the cab opens up like a sun porch on a glass-bottom boat, delivering a view of the work area and key components that has never been possible before.

Equally dramatic is the ease and precision with which an operator can manipulate the blade and control the machine. For an inexperienced operator, the controls make it possible to attain rudimentary efficiency in a matter of hours, rather than weeks or months. For an experienced blademan, they provide an opportunity to work as effectively at the end of the day as at the beginning, free of stiffness and tension, and to attain an extra degree of precision thanks to the extra visibility and the precision controls.

That the joystick controls save wear and tear on the operator and dramatically reduce operator movements is a matter of scientific fact. Caterpillar commissioned a University of Wisconsin motion study that found the M-series joystick controls reduce elbow and wrist movement by 78% compared to the conventional controls in an H series grader.

Lower ownership cost

In addition to the control system, Cat used the M-series to bring several other new features and a host of catch-up improvement to market. For many grader owners, are a pair of the most important innovations in the M series is two design changes that remove thousands of dollars of labor from the maintenance of the drawbar, circle, and moldboard operation.

In the M-series, access to the drawbar wear inserts is on the top of the circle. An operator or technician simply removes two bolts and a protective steel plate to add or replace shims to keep the system tight. The previous design required dropping the circle shoes to make shim adjustments, making it a laborious, two-person job.

Cat has also introduced a patented new circle shoes retention system that eliminates the use of shims, using two slide rail wear inserts instead. The new bi-directional slide rail shoes allow adjustment up and down as well as fore and aft to eliminate moldboard chatter.

A county motor grader operator from Alberta, Canada who beta-tested an M-Series grader told Better Roads that these two design changes mean that circle moldboard adjustments now take less than an hour, versus three hours or more on previous designs. A Cat study estimates that circle moldboard adjustments on the M-Series require 78% less time than competing models.

All-wheel drive

Cat used the M-series to improve its all-wheel-drive package. The most basic change is going to two hydraulic pumps to power the front wheels — one pump for each wheel. The change adds 52% more torque than the single-pump H-series and the two pumps allow independent control of the hydraulic flow to each wheel. To compensate for hydraulic power demand when the machines operate in all wheel drive, the engine automatically delivers additional horsepower to provide constant power to the ground.

An electronic control module controls front wheel speeds automatically so that when the machine turns in front-wheel drive or all-wheel drive the inside wheel rotates slower than the outside wheel. This steering compensation feature gives the machine full torque through the entire turn and delivers a shorter turning radius.

Also new to the Caterpillar motor grader family is a front-wheel-drive-only hydrostatic mode for precision low-speed performance. In this mode, designed for working in tight spaces and other applications requiring enhanced control, machine speeds are infinitely variable from 0 to 5 miles per hour.
The all-wheel-drive option is available for the first time in the 120 model size (29,000 pounds, 125 horsepower), as well as in the 140 (32,500 pounds, 165 horsepower) and 160 (35,000 pounds, 195 horsepower).

Smooth downshifts

M-series graders feature Tier 3 engines, but Cat made several important changes to the drive train beyond meeting emissions requirements.

All models except the giant 24M feature direct-drive countershaft transmissions with electronic clutch for gear-to-gear and forward/reverse shifts. All models now feature a bolt-on rear axle module designed for reduced service time.

One of the most interesting new power train features is Cat’s new variable horsepower scheme. Standard on all models, the M-series VHP adds horsepower in 5-horsepower increments as the machine progresses to the next gear. The result, says Cat, is a smooth power curve that allows the machine to carry heavy loads while downshifting.

One upsmanship

For an equipment category that received very little attention through most of 1990s, motor graders have received an extraordinary dose of innovation over the past few years. Spurred to make changes for lower emissions engines, John Deere, then Volvo Construction Equipment, and now Caterpillar have taken turns trying to leapfrog in front of the pack by adding a variety of additional content.

Cat’s M-series is the latest case in point. The company claims it applied for more than 100 new patents in developing its new graders.

Most of Cat’s innovations and changes are practical, like the use of glare-reducing black paint on the top surfaces of the front frame, and the various improvements that make the machines easier and cheaper to service.

While veteran operators will appreciate the practical innovations, what seems certain to set the M-series apart from all other entries in the full-size grader category is the transition to joystick controls. And, of course, the big question is: Will veteran operators accept this radical change from the past?

Cat is betting they will and, as a conservative midwestern company, they have hedged their bets with extensive field trials. The veteran operators involved in those trials were enthusiastically positive about the changeover.

Cat further hedged its bets by developing an electronic training simulator that lets an operator adjust to the joystick controls before stepping into the actual machine.

The combination has a dramatic affect on inexperienced operators. At the press introduction of the M-series, a platoon of magazine editors who normally would reduce the demonstration area to something akin to a mine field actually operated the machines with modest success.

Reprinted from Better Roads Magazine
July 2006

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