Caterpillar 345D excavator

By: Geoff Ashcroft

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Caterpillar’s large excavators went through a gradual process of changes in the move from C series to D series. We take a closer look at the recently fettled 50-tonne class 345D.

Caterpillar 345D excavator
Caterpillar 345D excavator
  • Engine management system for power and fuel efficiency
  • Power Management for three different working modes
  • Can carry a much bigger bucket
  • Choice of three undercarriage arrangements to match varying application and transport requirements
  • Plenty of space in the cab

The 345D boasts more power, improved functionality and more productivity without incurring any fuel consumption penalty over the C series excavator it replaces.

Tipping the scales from 49,570kg to 52,230kg depending on boom and stick configuration, the 345D L excavator is the smallest of its HEX (heavy excavator) line-up.

This excavator still comes in two formats - reach boom specification with a 6.9m boom and choice of 2.9m or 3.35m dipper sticks, or shorter 6.55m boom and 2.5m or 3.0m sticks for mass-excavation.

Engine and power

Under the 345D's covers is a tweaked version of the C13 Acert engine - essentially the same 12.5 litre power plant as found in the 345C, but 385hp against the C's 325hp.

Caterpillar claims that despite the extra power, the machine still uses the same amount of fuel in tough digging and high duty cycles.

A wastegated turbocharger and mechanically activated unit injection with a clever engine management system, the C13 engine still delivers its peak power at 1800rpm.

The Power Management system allows the operator to choose from three different working modes to fine-tune the performance of the 345D to the application. These modes are High Power, Power Management and Economy.

There have been changes to the 345D's hydraulic system too. While the hydraulic system offers just two per cent more flow, the main implement pump has been redesigned, and an electric regeneration circuit has been added to boost hydraulic efficiency and reliability.

Maximum hydraulic flow is now 734L/min with system pressures operating at 350 bar under normal conditions, increasing to 380 bar during heavy lifts.

And hydraulic cross-sensing allows use of both hydraulic pumps. The result is improved productivity through faster boom, arm and slew speeds.

There is also an electrically controlled, hydraulic oil regeneration system on the boom to avoid sending oil all the way back to the tank, giving faster boom speed and better controllability, claims the company.

A cooling pack that uses radiators, oil coolers and intercoolers mounted side-by-side keep components cool. These are given a blast of air on demand using a hydrostatically driven and thermostatically controlled fan.

This design allows the excavator to be fitted with an optional auto-cleaning system that reverses cooling fan direction and simplifies machine maintenance.

All changes mean the 345D is able to carry a much bigger bucket compared to the 345C. In HD Reach Boom guise, the 345D can be equipped with a 2.8m3 bucket with each of two available dipper sticks, increasing to a 3.2m3 bucket in Mass Boom configuration.

Caterpillar's clever boom float system, Smart Boom, is fitted as standard. Smart Boom can be used in two working positions: it can float freely up and down when scraping or carrying out finishing work, or it can be set to float down only - useful for hammers or when truck loading from a bench.

Underpinning the 345D L is the choice of three undercarriage arrangements - fixed gauge, variable gauge and wide variable gauge. The variable gauge undercarriages allow 500mm to be removed form the machine's width.

Each option provides stability and the potential for a long working life, says the firm. Track links have also been redesigned to extend service life, and a new carrier roller design improves reliability, says the firm.

For extreme underfoot conditions or those jobs that dictate significant tracking is required, a cast idler and Positive Pin Retention 2 (PPR2) track can be specified.


Caterpillar has added a 24-volt power port in the battery compartment to accommodate electrical equipment when working on the machine. There's also an electric refuelling pump located in the battery compartment, along with the secondary fuel filter.

The machine uses a clever hydraulic capsule filter located outside the oil tank that filters oil as it returns to tank. Equipped with a two integral valves, the cassette-type filter self-seals once removed from the hydraulic oil tank, making replacement a clean, easy task says the firm.

Performance and handling

Our test machine, a 345D with 6.99m reach boom and 2.9m dipper stick, was fitted with the 2.8m3 bucket - offering some 25 percent more capacity than that fitted to the same spec 345C. I had high hopes for this 50,220kg machine.

There's plenty of space in the 345D's cab, including a large shelf behind the seat.

While it's a smooth running six-cylinder, there is no need to glance at instruments to check its running - this is an engine that makes itself heard.

With auto idle activated, a flick of the controls combined with full throttle setting sees the big Caterpillar rumble into life, and I head for the bench where a 740 Ejector ADT is waiting to receive a few passes from the 345's generous bucket.

The machine tracks effortlessly, and with 1800rpm on the throttle, works equally as effortlessly off the bench. Using the excavator's full reach and digging envelope, I realise there are no pauses or slow moving sticks - every input at the joysticks rewards you with a level of speed and precision not usually found on such a large machine.

I switched to cleaning the base of the bench in readiness for the next truck and activate the Smart Boom to allow me to float the bucket on the ground contours. No problems here, either, once I remember to put the boom into its float position.

The machine benefits from boom and swing priority that gives automatic emphasis on boom raise and slew functions, which, Caterpillar says, eliminates the need for different work modes to reassign machine priorities for different applications. And in this instance, it's clearly noticeable when truck loading from a bench.


I interrogate the on-board monitor to get to the E-ceiling functions. Once chosen, the screen reveals an image of an excavator with an arrow pointing from a baseline at ground level to the top of the boom, and this coincides with a height measurement in the lower part of the display that reads 5.3m. This is the distance from the floor to the top of the boom. It's an instant measurement and raising the boom changes the distance on the display.

To activate the ceiling, I simply position the boom at the desired maximum working height and confirm this by holding down a confirmation button on the right hand console. The display shows a solid white triangle to confirm my height limit and is accompanied by a continuous buzzer sound and a red light. It really is that simple.

Lowering the boom removes the light and buzzer, but each time I try and raise the boom, the system automatically slows the lift height as my limit is reached - and the buzzer warns me I'm getting to closer to the preset working height. To move the boom past the chosen lift height, you have to make a conscious effort to disarm the E-ceiling.

The combination of speed, strength and agility now available from the large 345D will be considered essential qualities that are sure to benefit many more operators.

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