The PM620 and PM622 are powered by a Cat C18 ACERT engine, a turbocharged, 6-cylinder diesel engine that provides 470 kW (630 hp) of gross power. The C18 engine meets U.S. EPA Tier 4 Final and EU Stage IV emission standards. The engine is iso-mounted to reduce vibration and increase operator comfort.
The Automatic Engine Speed Control feature allows the engine to optimize output to match the load, reducing excessive fuel consumption and wear on the engine.
The turbocharged air-to-air aftercooling system provides high horsepower with increased response-time while keeping exhaust temperatures low, which generates significant improvements in airflow. This increases efficiency and reduces emissions.
The cooling system provides cool intake air in order to maximize fuel efficiency and minimize emissions. An on-demand variable speed fan draws ambient air from the top of the engine hood and through the cooling package, keeping the engine compartment cool. Heated air exits from the rear of the machine, directed away from the operator’s station for greater operator comfort.
Undercarriage and Drive System
The PM620 and PM622 utilize a four-post design. The leg posts feature an auto-leveling function that provides smooth height adjustment without stepping.
The machines are fully hydrostatically driven by two variable displacement propel pumps supplying oil to variable displacement motors on each track. Drive motors are piston-type and automatically control displacement to provide maximum torque for work or greater speed for moving around the job site. A propel lever/steering joystick provides infinite control of the travel speed within the range.
The machines have a robust propel system with a diagonal cross flow design that provides exceptional traction. The pumps drive opposing track motors, front to back and side to side, to ensure the machine has power across the center of gravity of the machine. In extreme conditions, automatic traction control minimizes slippage by providing more power to tracks that grip.
There are several automated functions to simplify operation. The operator’s platform has a ‘hold’ button to stop the machine and pause various functions while making truck interchanges or job stops. It returns to previous working speed and functions when deactivated. There is a speed limit to allow the operating speed to set to ensure consistent operations. The machines are equipped with position sensing cylinders in the posts and hydraulic systems, providing basic machine function improvements such as service height indications and rear leg auto-stop. It also enables the optional Cat Grade Control system to include additional capabilities.
The drive tracks are based on durable, proven Caterpillar designs and components. Track tension automatically adjusts to ensure optimum operation. Track assemblies are 1788 mm (70.4″) long, 305 mm (12″) wide and feature replaceable, bolt on polyurethane track pads for long service life.