Cats Decades of Development In Grader Design

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Updated: December 2, 2018

The modern motor grader is one of the most flexible and productive items of plant available. Here, Caterpillar Product Specialist, Darren Hodge explores the historical development of the machine and the latest technology available.

As the tough times of the great depression swept the world, Caterpillar continued development of a range of new products. One of its innovative developments was the road machinery division’s July 1938 launch of the Diesel No. 12 Auto Patrol – the first of the long line of products now more commonly known as the motor grader.

The Diesel No. 12 became one of the most recognised and longest running models of the Cat Motor Grader product line.

The 1938 launch was via a demonstration to a group of excited Cat dealers in Peoria, Illinois. The unique design of the Diesel No.12 featured many of the hallmarks of the modern motor grader seen today.

The stylish, heavy-duty self-propelled machine delivered efficient and economical road building and maintenance work at the height of a nationwide road building and infrastructure development program across America.

Featuring a range of useful blade positions that surpassed all competitors, it also featured high and low bank-cutting positions and allowed the blade to be turned completely around to face backwards meaning the operator could continue grade work while driving in reverse.

In short stretch grading, sub-grade work, or in shaping bad spots or areas where turning was difficult, it meant an operator could continue to work productively for longer.

With the blade now centre mounted on the blade beams, the new Auto Patrol also permitted a correct ditching position on either side, with the toe of the 12-foot blade directly behind the front ditch wheel and ample clearance to prevent clogging.

Power on the No. 12 was delivered via a six cylinder Cat diesel engine producing 66 brake horsepower mounted over the drive axle – the design taking advantage of the engine weight to limit wheel slippage.

A gasoline-starting engine made for easy starting in the widely varying North American weather conditions.

The transmission offered six forward speeds and two in reverse. A low speed provided both maximum pull for the heaviest jobs and precision control for fine grading. Second speed permitted faster operation for most ditching and other heavy work; while the higher gears provided an ample speed range for a mix of roadwork, snow removal and travel.

The Caterpillar Diesel No. 12 Auto Patrol was even equipped with two-speed powered mechanical blade controls. A simple shift of a lever gave the operator faster control for the longer blade movements required during coarse work. For close finishing work, a slower control setup provided extreme accuracy in blade settings. The No. 12 Auto Patrol was an early example of Caterpillar using innovative technology to provide customers with the solutions they demanded.

The “No. 12” model number designator has now adorned Caterpillar machines for more than 80 years – the longest of any model number in the company’s motor grader product line-up.

The focus on addressing customer demands has continued to this day with an expanded product line together with a range of service and support offerings. The current 12M Motor Grader model is an example of this.

The 12M series line-up features leading edge technology helping owners to achieve productivity advantages and assist operators to reach greater levels of control in grading applications.

All motor graders generally require multi-function operation for positioning of the steering, drawbar, circle and moldboard functions, making them one of the most complex machines to operate and master to achieve accuracy in final trim surface applications in a consistent and seamless manner.

However, the three axis joystick controls on the Cat M Series grader provide operators with superior control in achieving complex road building and finishing tasks.

And, the standard fitment electro over hydraulic joystick controls in the M Series have been the basis for further technology advances since their introduction.

Examples include the fully integrated factory-fitted Cat Grade Control Cross Slope system. This adds to job-site productivity and speed and is ideal for maintaining roads as it allows operators to reach the target grade with fewer passes.

The Cross Slope system will automatically maintain target slope and compensate for the blade movement and circle rotation as well as the road or surface changes by utilising the three machine sensors and control module.

With the addition of the new Advanced Control Joysticks to actuate Cross Slope functions, the operation of the motor grader using Grade Control technology has become even simpler.

The industry-exclusive Advanced Control Joysticks also allow operators to manage Grade Control Cross Slope automation tasks without the need to remove their hands from the joysticks. Additionally, recent software enhancements have added further functionality by allowing the storage and saving or favourite Cross Slope target settings.

When multiple slope angles are needed– which are common in typical road maintenance tasks – the operator can recall preset target slopes without stopping to adjust the initial set slope target, and all at the touch of a button.

This new level of functionality means the operator can complete the job easier and become more productive simply by reducing the number of actions and time required to change target slopes.

System flexibility also allows operators to refine accuracy by allowing on-the-go changes to the slope position using either the favourites setting or the Cross Slope Toggle function.

The toggle selection mirrors the original set target slope when the blade position is swapped from left/right during a machine turn around.

This means the desired slope on the return run is set with the push of a button – meaning perfect road crowns built quickly and easily.

There is also a higher level of automation with the addition of Auto Articulation with steering, which reduces the hand function typically required to complete multi-function operations.

When engaged the grader automatically articulates when steering, with the articulation range finely tuned to follow the angle of the front steer wheels.

Auto Articulation improves grader manoeuvrability in tight working spaces, simplifies operation and with one less function to perform, reduces the number of hand movements required helping to reduce the operator’s fatigue. Completing a three-point turnaround is also faster with Auto Articulation making it a genuine benefit for the operator.

The M Series engine and transmission design enables smooth shifting between gear speeds and directional shifts.

The Controlled Throttle and Shuttle Shifting Technology enables directional and gear changes without using the transmission disconnect pedal.

Due to this technology, the only time the pedal operation is used is in start-stop operations.

Transmission upshift and downshift gear changes can be completed under full engine load (1st to 4th gears) and consecutively Shuttle Shift from forward to reverse to forward (gears 1st through 3rd).

There is no need for the operator to stop in these manoeuvrers as the powertrain design adjusts engine speed for optimal shift points and to dampen the torque reaction between the engine and transmission.

These technologies assist in everyday operations such as when completing a road grading maintenance pass. For example, an unsealed gravel road is normally designed with different angles on the fore slope, shoulder and cross slope sections. On the first pass grading the fore slope angle is selected from the preset number via the Advanced Control Joystick. At the end of the pass, the operator can complete a three-point turnaround seamlessly with Auto Articulation and shuttle shift functions. Whilst approaching the return the operator can select Cross Slope Toggle to mirror the blade positioning from the first pass and select the new target slope for the shoulder pass.

On previous generation motor graders without this level of technology, this application would have only been possible with stop start operations.

Combined, many of the latest technology features in the M Series Motor Grader enhance multi-function capability, dramatically improve operational efficiency, boost productivity levels and provide greater operator comfort.