CAT 320 Excavator Review

The 20-tonne class Caterpillar most Australian contractors compare everything else against. What separates a 320 from a 320 GC, why the emissions build changes your running costs, and what to inspect.

The Cat 320 is Caterpillar’s 20-tonne class hydraulic excavator, the size that does most of the earthmoving work in Australia — civil subdivision, bulk earthworks, drainage, road maintenance, quarry support and general hire. Caterpillar launched it alongside the 320 GC and the 323 in December 2017 as the Next Generation replacement for the previous 320-series machines.

If you are buying in this class you are almost certainly comparing a 320 against a Komatsu PC210, a Hitachi ZX210 or a Volvo EC220. This post is about what the 320 specifically is, and what changes between the versions of it that are sold here.

The 320 and the 320 GC are different machines

This is the distinction that trips people up in listings. The GC is not a trim level. Caterpillar positioned it for low to medium duty applications with a simpler cab, less technology and a lower engine rating, sold on lower hourly owning and operating cost. The standard 320 has more engine output, more weight, and the Cat Grade with 2D, Grade Assist, Payload and E-fence technology package.

For a hire fleet doing batter trimming and trenching, the GC is often the right machine. For a contractor doing production earthworks with grade control, it usually is not.

The variants sold in Australia

Australian-delivered machines come in more than one emissions configuration, and the engine and weight change with it. This is the single most common source of wrong figures in classified listings.

The Tier 3 equivalent machines are certified to Brazil MAR-1, which Caterpillar states is equivalent to US EPA Tier 3 and EU Stage IIIA. Earlier Tier 4 Final 320 spec sheets quote a lower 121kW rating and 22,500kg, so the year of build matters as well as the emissions family.

Operating weights in every case are quoted with a stated configuration — boom, stick, bucket, shoe width and counterweight. Change any of those and the number changes. Do not compare a listing’s weight to a brochure figure without checking what the brochure was measuring.

Hydraulics and dig envelope

The 320 runs two main pumps for a maximum implement flow of 429L/min, with maximum equipment pressure of 35,000kPa and 38,000kPa available in lift mode. Maximum swing torque is around 74kN·m and maximum drawbar pull around 205 to 206kN, depending on configuration.

Dig envelope is close between the variants and small differences are configuration-driven rather than meaningful.

Where the money goes after purchase

Fuel and undercarriage dominate, in that order, and neither is a function of the badge. Caterpillar claimed at launch that the Next Generation machines used 20 to 25 per cent less fuel and cost up to 15 per cent less to maintain than the models they replaced, through longer service intervals. Treat that as the manufacturer’s claim against its own previous machines, not as a comparison to a competitor.

Published intervals on the 320 family are useful, though: hydraulic oil out to 3,000 hours, fuel filters at 1,000 hours and air intake filters up to 1,000 hours, with engine oil and filter changes scheduled at 500, 1,000 or 2,000 hours depending on the maintenance schedule the machine is on. Refill capacities are 345 litres of fuel, 234 litres in the hydraulic system and 15 litres of engine oil.

Then there is transport. A 21 to 23 tonne machine plus a float is a heavy combination, so factor in either a truck and trailer of your own and the licence to drive it, or a standing cartage cost every time the machine moves.

The Australian dealer reality

Cat is sold in Australia through territory dealers rather than one national network: Hastings Deering covers Queensland and the Northern Territory, WesTrac covers Western Australia, New South Wales and the ACT, William Adams covers Victoria and Tasmania, and South Australia has its own dealer again.

For most buyers this is a strength — these are large, well-resourced businesses with regional branches and deep parts holdings. The thing to know is that your relationship, your service pricing and your parts availability are with your territory dealer, not with Caterpillar. If you buy a machine from interstate, confirm how your local dealer will handle it before you commit.

What to watch for on a used one

Undercarriage is the largest single cost item on any tracked machine and the hardest to disguise. Track chains, idlers, rollers and sprockets tell you what the machine actually did, and a full undercarriage on a 20-tonne machine is a serious number.

• Pin and bushing wear through the boom, stick and bucket linkage. Work the machine and watch for slop.
• Final drives and the swing bearing. Ask for oil samples on both, and listen for noise through a full slew under load.
• Cylinder condition — scoring on rods, weeping seals, and drift when the machine is parked with the boom raised.
• Product Link and VisionLink history. These machines are telematics-equipped from the factory, so real hours, fault codes, idle percentage and duty cycle are recorded. Demand the report. A seller who cannot or will not produce it has told you something.
• Aftertreatment on Tier 4 Final machines: DPF ash loading and regeneration history, and whether DEF quality has been managed. On a Tier 3 machine this section does not apply, which is part of why they still sell well here.
• Attachment plumbing. Auxiliary and hammer circuits, quick coupler type, and whether the buckets in the photographs are actually included.
• Hours against condition, not instead of it. Idle hours inflate the meter without wearing the undercarriage, so a higher-hour machine on a documented service contract is frequently a better asset than a lower-hour machine with no history.

Who shouldn’t buy one

If your work is predominantly rock breaking or high-duty hammer work, look hard at whether a 320 is the right size and hydraulic specification, or whether a 323 or a higher-flow machine suits you better. Sustained hammer work is what shortens the life of a machine in this class.

If you need a machine that can be moved on a tandem float without a permit, this is not that class of machine. If you want minimal electronics and something a bush mechanic can sort out, a Tier 4 Final 320 is the wrong choice and an older or Tier 3 machine is worth considering instead.

And if you are buying your first excavator, be honest about whether you need the grade control technology you are paying for. A 320 GC with a good undercarriage will earn more than a technology-loaded 320 you cannot afford to keep serviced.

Resale and what holds value

In the 20-tonne class, resale tracks undercarriage condition, documented service history and hours — roughly in that order — far more than it tracks the badge. Cat’s advantage is depth of market: there are a lot of these machines in Australia, a lot of operators trained on them, and parts in every state, which means a tidy 320 is liquid.

The variables that most affect what a specific machine is worth are the ones people forget to ask about: emissions build, whether the machine has grade control, undercarriage percentage remaining, and whether the telematics history is available. Get all four before you negotiate.

We do not publish a resale percentage for this model. What we do publish is what Australian dealers are asking for Caterpillar machines right now, which is the number you can actually use.