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Mon October 30, 2017 - National Edition
The Cat PM820, PM822 and PM825 cold planers are designed to be highly productive, highly maneuverable, half-lane milling machines capable of controlled full-depth removal of asphalt and concrete pavements in a single pass. Operating weights for the new models range from 79,630 to 82,650 lb. (36,130 to 37,500 kg), and cutting widths from 79 to 98.6 in. (201 to 250 cm). All three new machines use the Cat C18 ACERT engine, rated at 563 kW (755 hp), meeting EPA Tier IV-Final/EU Stage IV emission standards, and are ISO-mounted to reduce vibration.
The high-horsepower C18, with an advanced turbo-charging and air-to-air after-cooling system, responds quickly to operating demands, while keeping exhaust temperatures low and maintaining needed airflow for optimum efficiency and reduced emissions. For added efficiency, the cooling system uses an on-demand, variable-speed fan that draws ambient air from the top of the hood and through the cooling package, then expelling heated air from the rear of the machine — directing air away from the cab for operator for safety and comfort. The system also reduces temperatures in the engine compartment.
The PM820, PM822 and PM825 are hydrostatically driven by two variable-displacement propel pumps supplying oil to a variable-displacement motor at each track. Drive motors are piston-type and automatically control displacement, providing optimum torque for work or optimum speed for maneuvering.
The propel system's diagonal-cross-flow design delivers exceptional traction, with the pumps driving opposing track motors, front-to-back and side-to-side, to ensure that the machine has power across its center of gravity. In extreme conditions, an automatic traction-control system minimizes track slip by providing more power to the tracks with greater traction.
A single propel/steer joystick provides infinite control of travel speed within the range, and automated functions simplify the operator's task, such as pushing a single button to stop the machine and pause functions when making truck interchanges. A second button push resumes machine operation. Also, a speed-limiter allows setting travel speed to ensure consistent operation.
The drive tracks — based on Caterpillar designs and components — are 70.4 in. (179 cm) long and 12 in. (30.5 cm) wide, featuring replaceable, bolt-on polyurethane track pads for long service life. Track tension automatically adjusts to ensure optimum operation.
Four-mode steering is standard, with an electronic control module that processes inputs from sensors on the front and rear tracks, along with input from steering-selector controls. The system provides precise, simultaneous track movement in the crab- and coordinated-steering modes, while automatically realigning the rear tracks to center when the front-tracks-only steering mode is selected. In the coordinated mode, the inside turning radius is a tight 6.42 ft. (2m), providing enhanced maneuverability in confined spaces, according to the manufacturer.
A true-tracking alignment function provides steering precision, smoother cornering and reduced track wear. This function makes small adjustments to the alignment of individual tracks to ensure that tracks are travelling in the optimal direction to make required maneuvers without dragging the tracks, thus optimizing the turn radius and extending track-pad and undercarriage life.
The PM820, PM822 and PM825 use a four-post design, with each leg post featuring an auto-leveling function that provides smooth height adjustment without stepping. Position-sensing cylinders in the posts and hydraulic system provide basic machine-function enhancements, such as service-height indications and rear-leg auto-stop. The design also enables the optional Cat Grade Control system for additional capabilities.
The rotor is equipped with durable, three-piece, quick-release tool holders and carbide-tipped cutting bits arranged in a chevron pattern for maximum breakout force. Optional rotor systems are available, as are Cat Diamond Bits for enhanced cutting performance in specific applications. The cutting chamber features a design that facilitates material flow, reduces wear on the chamber and provides flush-cutting capability.
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 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.
Three cutting settings, controlled electronically from the keypad, are available to match rotor speed/torque with operating conditions. A standard automatic load control feature enhances machine productivity via an electronic control module that continually evaluates engine speed and regulates propel speed as required to maintain performance for maximum output.
The quick-release conical tool holders feature a tapered fit, maintaining tightness in the holder base. The mandrel uses large, replaceable, carbide-faced loading paddles to move milled material to the collecting conveyor for high production and reduced wear on the inside of the rotor chamber and cutting tools. Triple-tree cutting-bit placements on the rotor end cutters provide optimum bit spacing to clean up loose material and to reduce wear on the drum when maneuvering in the cut.
Optional Cat diamond bits offer the ultimate in cutting performance, lasting up to 80 times longer than conventional carbide bits to extend intervals between bit maintenance, increase production, reduce operating costs, and eliminate the need to purchase and store pallets of carbide bits, according to the manufacturer. Cat diamond bits are sharper than conventional carbide bits, allowing the machine to cut faster and to reduce drag on the cutting system for better fuel economy — and also for reduced vibration, resulting in greater operator comfort and further-reduced operating costs.
The seamless collecting-conveyor belt, with 1.25-in. (3.2-cm) high cleats and a width of 33.5 in. (85 cm), 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. The spray system automatically activates when the rotor is engaged and the machine is moving forward, a feature that conserves water, which is triple filtered. A gauge monitors water pressure, and a low-water-level indicator helps manage water stops. Also, an onboard winterization system is included, providing a simple method for purging waterlines with pressurized air.
The 898-gal. (3,400-L) water tank can be filled from standard wide-fill openings on top of the machine, or from the standard ground-level port at the rear of the machine. A side-fill port is optional, allowing adding water while the machine is operating. A water-transfer pump is available to facilitate additional filling options.
An additional water spray system can be fitted as an option for greater lubrication, cooling and dust reduction in heavy-duty applications. This system includes an additional water pump, a second spray bar (located in the rotor chamber housing) and extra spray nozzles on the collecting conveyor. An optional dust-abatement system uses a vacuum system that pulls dust from the collecting conveyor and from the transitional zone between the collecting and loading conveyors. The dust is ejected through the loading conveyor, along with the discharge material.
The hydraulically controlled front loading conveyor — equipped with upper aluminum covers for added protection against material spills and blowing fines — features height adjustment for raise and lower, as well as two cylinders for 60-degree swing left and right of center, which are controlled from the operator's station or from ground-level control stations. The loading conveyor also can be hydraulically folded downwards, reducing machine dimensions during transport.
Cat Grade Control
The PM820, PM822 and PM825 can be equipped with the optional, integrated Cat grade control system, which is a 2D-capable/3D-ready grade-and-slope system that automatically controls a preset rotor depth and cross slope. The system can be enhanced for full 3D control with the addition of optional equipment.
Cat grade control can be configured with contacting or non-contacting grade sensors including Cat sonic sensors and mounting hardware, the side plate position or optional inboard ski. Machines can be set up either to control grade on both sides, using any combination of sensors, or, set up to control grade on one side and slope on the other. The system allows changing sensor arrangement during operation with simple commands.
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 ± 1/8 in. (3 mm).
The operator's station features dual operating controls, including upper-conveyor controls and rear- track steering controls. An ergonomic instrumentation layout is designed for ease of use, and the touch-screen display is visible in all lighting conditions, with keypads backlit for low-light operation. The touch-screen display provides easy-to-read gauges, function indicators, and warning indicators, as well as displaying video from optional remote cameras.
A computerized monitoring system includes electronic control modules that constantly monitor system pressures and engine conditions with multiple modes of operation. The system can provide self-diagnostics and fault codes to the touch-screen display. An optional second display provides an additional monitor for machine functions.
A large storage locker is standard. Options include suspension seats and a hydraulically operated canopy, which can deploy and retract to a storage position without disrupting operation. The canopy can be equipped with optional front and rear windscreens that protect the entire width of the operator's station.
The new machines are equipped with perimeter lighting, allowing safe low-light operation. An LED lighting system is available. In addition, the operator's platform has floor lighting that activates with a button push from any control station for visibility when accessing the machine in low light conditions. An optional remote camera system, using either one or two magnetically mounted cameras, provides views to the front and/or rear of the machine.
Large doors open wide to provide access to the engine, emissions package, air filter, hydraulic components, and daily service points. The machines feature extended service intervals to reduce owning and operating costs: 500-hour engine-oil service and 3,000-hour hydraulic-oil service, which can be extended to as long as 6,000 hours with scheduled oil sampling.
An auxiliary electric pump drive provides emergency hydraulic flow that allows a disabled machine to manage essential machine functions and be towed away so as not to disrupt work.
The hydraulic rotor service door opens wide for convenient access to the rotor for inspection and tool maintenance. The engine-mounted air compressor and cutting bit removal tools facilitate changing cutting tools. An optional rotor-turning attachment is available to turn the rotor during cutter-bit replacement. Hydraulic hoses are held neatly in place with polyurethane routing blocks, which separate hoses to reduce possible abrasion.
Wiring for the electrical system is protected by nylon-braided wrap, and sealed connectors ensure electrical-system integrity. Electrical wiring is color-coded, numbered, and labeled with component identifiers to simplify troubleshooting. Two maintenance-free Cat batteries, located at the rear of the machine and accessible from ground level, deliver maximum cranking power and resist vibration damage, further ensuring reliability of the 24-volt electrical system.
Other features that simplify service include leak-resistant O-ring face-seal hydraulic fittings, grouped quick-connect hydraulic test ports, scheduled oil-sampling ports, visual sight gauges and remote grease points.
Additional options for the new cold planers 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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