Power Train – Engine
The C18 and C9 engines with ACERT Technology work at the point of combustion to optimize engine performance and minimize exhaust emissions. Matched with the torque converter and power shift transmission, they provide years of dependable and efficient service. A combination of innovations working at the point of combustion, ACERT technology optimizes engine performance while meeting regulations for off-road applications. The tractor for the 631G and 637G is powered by the C18 engine with ACERT Technology. The large displacement and high torque rise provides optimal performance in the load, cut, haul and return. Matched to the high efficiency torque converter and electronically controlled power shift transmission, it will provide years of dependable service. The 637G has a C9 engine with ACERT technology that provides additional power to assist in loading as well as improve hauling performance on grades.
ACERT Technology
Caterpillar optimizes engine performance while meeting U.S. EPA Tier 3 and European Union Stage IIIa regulations. ACERT Technology reduces emissions during the combustion process by using advanced technology in the air and fuel systems, in conjunction with integrated electronics. Caterpillar meets emission regulations at the combustion source rather than recycling exhaust gases.
Dual Horsepower
Cat engines have dual horsepower capability with the low power setting in torque converter drive and the high power setting in direct drive. If the auger is engaged while the machine is in torque converter drive, the machine automatically goes to the high power setting. On the tandem engine scraper, the rear engine has dual horsepower capability that results in better performance on the haul roads.
Mechanical Electronic Unit Injection (MEUI)
The MEUI system with variable shaped injection patterns provides for optimum combustion based on altitude and temperature. The Cat MEUI fuel system is a highly evolved fuel system with a proven record of reliability in the field. The system combines the technical advancement of an electronic control system with the simplicity of direct mechanically controlled unit fuel injection pressure. These features allow the C18 to completely control injection timing, duration and pressure.
Electronic Control Module
The ECM responds to operator commands and engine sensor input to optimize engine and machine performance. This advanced engine management software controls and protects the engine at all times against cold starts, high altitude operations and air filter plugging by monitoring: - injection timing and pressure
- engine cooling fan speed
- ether starting aid
- hydraulic pumps.
ADEM A4 Control Module
Controls engine rpm by adjusting the fuel duration, which results in quicker starts in hot and cold weather, better fuel economy, better operator response, and automatic compensation for altitude and filter plugging.
Reduced Exhaust Smoke
The ADEM A4 controller monitors electronic sensors to determine the optimum fuel/air ratio. Fuel is precisely controlled during cranking, starting and acceleration to reduce smoke. The Engine Electronics are faster and more efficient than mechanically controlling the governor rack position.
Altitude Compensation
The system de-rates fuel delivery as a function of barometric pressure as sensed by the system’s atmospheric pressure sensor. No manual adjustment is required. Auto deration prevents excessive combustion temperatures that could result in component damage.
Diagnostic Capability
Cat Electronic Technician (Cat ET) is used to display real-time pressures, temperatures, fuel settings and diagnostic messages as well as historical information such as engine over-speeds, overheating, low oil pressure and air filter restriction events.
Fuel Economy
Electronic controls optimize the timing setting for varying load conditions. The ADEM A4 controller matches timing to the load on the engine, engine rpm and temperature.
Air Filter Restriction
ADEM A4 controller monitors air filter restriction and sends a warning message to the Electronic Monitoring System (EMS III) to alert the operator if the restriction exceeds the allowable limit.
Automatic Belt Tensioning
Both the tractor and scraper engines have automatic belt tensioning rather than manual tensioning. The number of belts has been reduced to two on the tractor, and two on the scraper. Fan drive bearings on both the tractor and scraper engines with ACERT technology eliminate servicing requirements.
Instrument Display Panel
Features a new quad-gauge layout showing engine coolant temp, transmission/torque converter oil temp, fuel level, and system air pressure. The 637G tachometer can monitor either front or rear engine speeds. Once the 637G tractor engine has been started, the operator can start the rear engine from inside the cab using a switch on the instrument panel. EMS III can display both front and rear engine information right in the cab.
Engine Speed Lock Controller
Enhances operation during long haul cycles by allowing the operator to maintain a desired engine speed without maintaining pressure on the throttle.
Simplified System
The electrical system has been redesigned to utilize three electronic control modules (ECM) on the tractor instead of four. The rear-powered scraper now has two ECMs rather than three.
Combined EMS Monitoring
The Electronic Monitoring System (EMS III) is designed to monitor both the tractor and scraper from one location instead of two. Both the tractor and powered scraper use the same controller for parts commonality and easier servicing.
Greater Reliability
The EUI system has fewer moving parts than mechanical unit injection and requires few adjustments. The ADEM A4 controller communicates with the monitoring system (EMS) to warn the operator when problems arise, helping to avoid major damage.
Tandem Engine
Two engines ensure the power to handle steep grades and make possible all wheel drive to handle soft, slippery underfoot conditions.
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