Caterpillar is introducing a revised line-up of 20-24 tonne E Series crawler excavators. The Cat® 320E, 323E and the reduced radius 320E RR adopt the EU Stage IIIB Cat C6.6 ACERTTM engine, providing reduced emissions and fuel consumption savings of up to 11%, compared to comparative D Series models while providing fuel savings of 8% and 9% respectively.
Operators will appreciate an improved cab environment, with a wider range of seating including heating and cooling options. Time delay lighting, additional safety handrails and improved serviceability make these mid-weight excavators an ideal choice for both contractors and rental companies.
Low Emission Engines Deliver Fuel Benefit
The two conventional bodied models, along with the reduced radius 320E RR, are powered by a Cat C6.6 ACERT diesel engine. Rated power is 152 hp (112 kW for the two 320E models, and 165 hp (121 kW) for the larger 323E. This proven engine uses a suite of technologies, including the Cat Electronic Control Module (ECM) in combination with the Cat Clean Emission Module (CEM) to meet the EU Stage IIIB emissions standards. The CEM incorporates a Diesel Oxidation Catalyst (DOC) and a Diesel Particulate Filter (DPF), and a passive regeneration system that automatically cleans the DPF throughout the working cycle of the machine without requiring operator intervention or disruption to operations.
On the 320E and the 320E RR, the power management system provides two operating modes for the operator, high power mode and an economy mode. On the 323E, a third middle mode is offered. An isochronous engine speed control ensures that the engine speed remains constant regardless of hydraulic demand. It also reduces idle speed under no load, cutting fuel consumption further.
The three excavators feature an automatic engine idle shutdown system that will shut the engine down when it has been idling for more than a customer-specified amount of time. This idle period can be set between 1-60 minutes. In addition an automatic engine speed control reduces engine revs by 100 rpm when the machine is not under load for more than five seconds, helping to save fuel and cut emissions.
The fuel system on the C6.6 ACERT is equipped with an electronically-controlled high pressure fuel injection system, featuring three-layer hoses, making it capable of running on bio-diesel up to a 20% mixture (EN 14214 or ASTM 6751) without additional adjustment.
Outstanding Hydraulic Performance
E Series excavators use a twin-pump open-centre hydraulic system with a highly efficient back-to-back main hydraulic valve. As with the D Series machines, the E Series models regenerate the flow of oil from the head end of the boom cylinder to the rod end during a boom down operation. However while on the D Series this regenerative flow is controlled using a hydraulic valve, on the E Series machines there is an electric valve to maximize efficiency and reduce pressure loss, increasing fuel efficiency.
The machines’ ECM has been upgraded to manage this electronic control of boom regeneration, along with negative flow control. It also manages a swing priority circuit valve and the stick regeneration circuit. In addition the ECM monitors the after treatment sensors, ensuring that temperatures and soot levels remain within preset ranges.
Dredging Today Staff, May 4, 2012; Images: cat