Caterpillar's new addition to its D-Series track loader lineup, the 973D, features load-sensing hydraulics, joystick steering, a new operator's station with tilting cab, and 10% more power than its 973C predecessor for harsh applications such as steel mills, landfills, quarries, and demolition sites.
Carrying on what Cat describes as the 973C's "all-purpose performer" reputation, the new machine retains many design features, including Cat's C9 engine, hydrostatic drive, single-fabrication mainframe, Z-bar loader linkage, and oscillating undercarriage.
New for the 973D is a closed-center, load-sensing implement hydraulic system that uses a variable-displacement pump to produce only the precise volume of oil actually required for a particular job. By contrast, the 973C's hydraulic pump produced a constant oil volume, whether required or not. This design change results in the 973D pumping less oil, thus conserving fuel, generating less heat, and freeing power to drive the tracks more efficiently. Cat says the new system also allows seamless, simultaneous use of lift, tilt, and travel functions.
Complementing the new hydraulic system are lift and tilt cylinders that use position-sensing electronics to allow operators to set lift and tilt kick-outs from the cab. Kick-outs are quickly reset for each job—or even each truck—to ensure fast cycle times. In addition, end-of-travel snubbing ensures that cylinders stop smoothly with less shock.
Either joystick steering or pedal steering is available for the cab. The steering joystick also provides transmission control, allowing the operator to effortlessly select travel direction and ground speed, while the pedal-steer system works in conjunction with the Cat "V-pattern" transmission controller.
Loader controls are available in either joystick or two-lever configurations. As opposed to the 973C that had console-mounted controls that were pilot-actuated (hydraulically assisted), loader controls for the 973D are seat-mounted and electrohydraulically actuated. The new low-effort controls move with the operator as the seat is adjusted, transmit less vibration, and provide precise hydraulic response, says Cat.
The new cab is rated at 74 dBA, sealed, pressurized, air-conditioned, resiliently mounted, and tilts (30° in the field, 90° in the shop) for access to major components. An increased use of glass offers improved visibility, and the new fender design yields sharper sightlines out the rear window. The dash includes both a gauge cluster that monitors vital systems and a display screen that provides real-time performance and diagnostic information.
The 8.8-L, 263-net-hp (196-kW) Cat C9 diesel engine meets U.S. EPA Tier 3 and EU Stage IIIA standards. It comes with Cat's proprietary ACERT technology for emissions-control and fuel-economy benefits. A new on-demand, viscous-clutch cooling fan helps further lower fuel consumption and sound.
An electronically controlled Cat Hystat hydrostatic drive system powers and controls each track independently via a variable-displacement pump and motor. The Hystat system allows both tracks to be powered through gradual turns, simplifies straight-line travel when working across slopes, and provides improved maneuverability with its counter-rotation capability.
The 973D's main-frame/loader-tower is fabricated of single-slab primary rails, cross-member reinforcing, and castings or forgings in high-stress areas to provide long-term durability for supporting multiple rebuilds. Oscillating track frames help smooth the operator's ride, lessen shock loads to the machine, and contribute to stability. A Z-bar-type loader linkage uses massive single-slab boom arms and dual bell-cranks (each with its own tilt cylinder) for improved breakout power.
Besides offering custom engineering solutions depending on customer needs, a variety of standard packages are available, including two Waste-Handling Packages (Standard and Extreme) that add substantial guarding, debris barriers, cooling-system enhancements, and an air-intake precleaner. The Standard Package is geared more for landfills, transfer stations, and material-recovery facilities, while the Severe Package is for more demanding work such as demolition.
Other optional packages available include a three-shank parallelogram ripper, multipurpose bucket, added counterweight, and a deluxe maintenance package for fast oil changes and fuel-sediment flushing.