Like every manufacturer of 75- to 174-hp diesel equipment, Caterpillar needed to repower high-volume machines such as backhoe loaders in order to comply with EPA emissions standards. Not content to simply comply -- and needing to add value to machines to balance the inevitable emissions-system price increase in buyers' return-on-investment calculations -- Cat refined the hydraulic system, added some electronic controls to improve performance and efficiency, redesigned its loader linkage and made maintenance easier on the F Series.
The Cat C4.4 engine applies what Peoria calls a Passive Plus diesel particulate filter. Passive Plus means operation of the DPF, with periodic regenerations to burn soot accumulated in the filter, is pretty much invisible to the operator. A back-pressure valve in the turbocharger manages exhaust temperature, holding it high enough even in heavy-idling applications to cook soot out of the DPF but low enough to protect the system. Most Cat machines introduced at World of Concrete 2012 deploy the same technology.
A larger torque converter in the 420F aims to improve loading and roading performance. Both the 420F and 430F have new electronic controls on their hydraulic pumps for improved power management and faster swash-plate response to changes in system demand. The results are better response to control input, faster cycle times and improved fuel efficiency.
Loader performance is boosted by new lift arms for both single-tilt and IT (Integrated Tool Carrier) models. Maximum hinge-pin height is 5 percent higher, maximum dump height is 7 percent higher, bucket breakout force is increased as much as 9 percent, and lift capacity at maximum height increased as much as 13 percent. Loader changes also improved material retention for IT models.
The nose of the hood is hinged at the top, allowing the grille and air-conditioning condenser to flip up for access to the radiator, hydraulic cooler, transmisson cooler, air-to-air aftercooler (the first on a Cat 420 backhoe) and fuel cooler.
New one-piece counterweights contribute to improved machine balance, and a new double-clevis swing casting, which brackets both the upper and lower flanges of the swing hinge, adds durability. The conical lower pin has been replaced by a cylindrical one that installs more simply.
The operator's station remains much the same as that on the E-Series backhoes, but Cat added electronic throttle control and now has auto-idle on a backhoe loader. Stop using the controls for a preset time (typically 5 to 10 seconds) and the system automatically drops engine speed to low idle to save fuel and allow clearer communication with workers on the ground.
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