Cat intros PM820, PM822, PM825 cold planers with grade control integration
Wayne Grayson | November 13, 2017

Caterpillar has introduced three new cold planer models that the company says are capable of controlled, full-depth removal of asphalt and concrete pavements in a single pass.

The new PM820, PM 822 and PM825 are each powered by a Cat C18 engine producing 755 horsepower. The turbocharged C18 features an air-to-air after-cooling system with a variable-speed fan. Cat says the engine “responds quickly to operating demands while keeping exhaust temperatures low and maintaining needed airflow.”

The half-lane milling machines weigh between 79,630 to 82,650 pounds and offer cutting widths between 79 and 98.6 inches.

Cutting

Each machine features three cutting settings controlled from a keypad. Cat says these settings match rotor speed/torque to the operating conditions at hand.

The rotor meanwhile is equipped with three-piece quick-release tool holders and carbide-tipped cutting bits arranged in a chevron pattern. Other rotor systems are available options along with Cat Diamond Bits which the company says are sharper and last up to 80 times longer than conventional carbide bits.

Here’s Cat’s full explanation of the cutting system process:

Chamber side plates move via independent hydraulic cylinders equipped with position sensors, ensuring that the side plates float at the proper level and eliminate binding. The hydraulically operated anti-slab device protects the collecting conveyor and ensures an optimum discharge opening to the rotor chamber. The chamber also features a right-side hinged door that provides access to the rotor. The moldboard, side plates, and anti-slab device all feature raise, lower, float, and hold functions. The system eliminates the need for a wire sensor by enabling the entire length of the side plate to function as an averaging ski for grade matching…

…The seamless collecting-conveyor belt, with 32-mm (1.25-in.) high cleats and a width of 850 mm (33.5 in.), is driven by a high-torque, variable-speed hydraulic motor that provides adjustable control of the loading conveyor to ensure proper discharge. A large chamber-discharge opening clears out the cutter box quickly and effectively controls fine particles. An optional system uses a grease cylinder to adjust belt tension and tracking (facilitating adjustment and reducing crew exposure to the spinning belt), but a conventional adjusting-screw system also is available.

A standard water-spray system lubricates the conveyor belt and assists with control dust. A centrifugal pump supplies water to the cutting chamber via spray nozzles, which spray in a flat-fan pattern to cool cutting bits. Nozzles are easily removed for inspection and replacement without tools…An additional water spray system can be fitted as an option for greater lubrication, cooling, and dust reduction in heavy-duty applications…

…The rotor drive system incorporates a dry clutch that drives a planetary gear reducer via two, six-rib, high-tensile-strength belts that use an automatic, hydraulically powered tensioner that prevents slipping and reduces maintenance. The clutch, coupled to the engine, is hydraulically actuated by the keypad controls on the operator’s console.

Drive system and undercarriage

Four-mode steering is standard on these machines and they feature a four-post design with each leg post outfitted with an auto-leving function.

Each of these three new cold planers are hydrostatically driven, offering what Cat says is “excellent traction” with “two variable-displacement propel pumps…driving opposing track motors, front-to-back and side-to-side, to ensure that the machine has power across its center of gravity.”

A single propel/steer joystick provides control of the machines with infinite travel speed control and automated functions assigned to single buttons.

The tracks on the machines are 70.4 inches long and 12 inches wide and feature replaceable, bolt-on polyurethane track pads with long service life. Tensioning and alignment are done automatically by the track system.

Operation and Cat Grade Control

Cat says the PM820, PM 822 and PM825 operator’s station features an ergonomic instrumentation layout, touchscreen and dual operating controls including upper-conveyor controls and rear-track steering controls.

A monitoring system allows operators to keep an eye on system pressures and engine conditions complete with self-diagnostics and fault codes. A second display is an available option for additional machine monitoring functionality.

Large locker storage comes standard on the machines and available options include suspension seats, and a hydraulically operated canopy that can be equipped with optional front and rear windscreens. An LED lighting system and a remote camera system are also available.

Another available option is the Cat Grade Control System. This 2D-capable/3D-ready grade-and-slope system automatically controls a preset rotor depth and cross slope. Cat says the cold planers can be set up with Grade Control using contacting or non-contacting sensors and the machines can either control grade on both sides or control grade on one side and slope on the other. The system also allows changing sensor arrangement during operation with “simple commands,” Cat says. Here’s a bit more detail from Cat on using Grade Control with these machines:

The position-sensing technology, coupled with the Cat Grade Control system, provides the machine with additional functions, such as an automatic plunge-cut feature that eases the rotor into the start of the cut. Also, a ramp-in/ramp-out capability provides a gradual, sloped entry into or exit from the cut. An auto-jump feature allows the machine to exit a cut, clear an obstacle, such as a manhole cover or grate, then to re-enter the cut at the previously set depth—all with use of a single button.

A cross-communication function allows the operator to view and change settings of control boxes located on the opposite side of the machine, providing a means of controlling both sides of a job from a single location. The system also provides a cross-coupling function, which ensures that an adjustment made to grade or slope on one side will automatically transfer to the opposite side, based on command parameters. Continual read-out for rotor depth and cross-slope is displayed on each control box and is visible in all lighting conditions. Sonic grade control sensors can be positioned on each side to provide a consistent accuracy of ± 3 mm (1/8 in.).

Further options include a diamond-bit cutting drum, in-board averaging ski with position-sensing cylinder, high-pressure wash-down system, bucket trays for cutter bit storage, high-capacity water-tank refilling pump, and electric refueling pump.

 

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