TipCon debut for 1.2-litre Cat
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by John Kendall • US engine manufacturer Caterpillar will launch its 7.2-litre 3126 engine in Europe at TipCon early next month.
Like the 10-litre C10 launched last year, the 3126 is fitted with Caterpillar's HEUI system which uses engine oil to pressurise the fuel, simplifying the design of the unit injectors. Injection timing and duration are both controlled electronically.
Caterpillar is pitching the engine at payload-conscious 6x2 and 6x4 tipper and mixer chassis operators. Foden will be the first chassis manufacturer to offer the 3126 in its compact-cab 2000 and 3000 Series models; Sandbach rival ERF is also believed to be testing the engine.
The deep-skirt block is made from cast iron with valve gear and fuel injection driven from the highmounted camshaft. Caterpillar claims a dry weight of 567kg.
The advantage of the HEUI system is that it can deliver fuel at high pressure independent of engine speed. Conventional electronic unit injector systems can only deliver fuel at the high pressures needed for the clean burning required by current emissions regulations when the engine has been running for some time.
The HEUI system works by drawing oil from the sump; the oil is then pressurised by a high pressure pump in a manifold. Pressure in the manifold is regulated by an electrically operated valve, controlled by the electronic control module (ECM). The oil acts against a piston in the unit injector, while the other end of the piston acts against the fuel pressurised in the injector.
The piston surface acting against the fuel is several times smaller than that acting against the oil so the high-pressure oil can exert a much greater pressure on the fuel, delivering the necessary high injection pressure. By controlling both the oil and fuel valves in the unit injector, the injection timing, pressure and fuel injected can be accurately controlled.
Like Cununins' electronically controlled Celect engines, the Cat's ECM pro vides other monitoring and data collection functions, including self-diagnostics and performance data such as fuel consumption, speed, engine hours, fuel used and distance travelled.