Excavators

Minis, 20-tonne crawlers, wheeled excavators and long-reach booms:

weight class is the first split, because it decides what the machine can dig and how it reaches the job. A mini of one to two tonnes rides on a trailer behind a pickup and fits through a house gate. A five-tonne Kubota or Yanmar digs a proper foundation but needs a truck. The 20-tonne class, the Cat 320 and Komatsu PC200 type, is the standard tool for subdivisions, basements and road cuts, and it travels only on a lowboy. Wheeled excavators drive on the road between jobs and suit utility trenches in town, where steel tracks would chew up the asphalt. Long-reach machines trade digging force for a boom that spans a river or a drainage canal. On a tight site, a skid steer clears the spoil while the excavator keeps digging.

Tail swing, track shoes and auxiliary lines on an excavator:

these matter more than the badge. A zero-tail-swing model keeps its counterweight inside the tracks as it turns, so it can dig beside a wall or in one lane of a street; a conventional tail is steadier with a heavy bucket at full reach. Rubber tracks on a mini spare paving and lawns but cut up fast on rock and rebar. On bigger machines, wide steel shoes stop it sinking in wet lowland clay, while narrower ones last longer on hard ground. If you plan to run a hydraulic hammer, a thumb or a tilting bucket, look at the auxiliary hydraulics before anything else. A hammer runs on a one-way circuit and a thumb needs flow both ways, and a machine plumbed for neither goes to the workshop before it earns anything.

A new 20-tonne excavator against one with hours on it:

a new machine of that size from Cat or Komatsu costs upwards of $150,000. A used one is priced less on its year than on what it is about to need, because a full undercarriage and a main hydraulic pump can each run to five figures. A machine due both is worth far less than its hours suggest; one that has just had them is worth paying for.

Pins, welds and the pump on a second-hand excavator:

set the bucket on the ground and have someone move the stick gently while you watch each joint. Slack at the bucket linkage means a cheap set of pins and bushings; slack at the boom foot does not. Look along the boom and stick for cracks and fresh welds, above all behind the bucket and where the boom meets the frame, and distrust new paint in exactly those places, where years on a hammer show first. Then ask the operator to raise the boom, curl the stick and swing at the same time. A healthy pump keeps all three moving; if one stalls or the engine bogs, the pump or a relief valve is tired. Drive it straight on level ground: drifting to one side, or oil around a drive hub, points to a weak travel motor or final drive. Pins, bushings and seal kits from industrial parts give you a real figure to set against the asking price. If the machine is still abroad, ask for a video made for you that shows the serial plate, the hour meter and those combined movements, and check the plate against the papers.

The serial plate, the hour meter and the ground it worked:

open the listing with weight class, make, model, year, hours and serial number, then the boom and stick, the shoe width and the coupler and pin size, since buckets only swap between machines with the same pins. List every bucket, thumb and hammer that goes with it and say which lines are plumbed. Film it digging, swinging with a full bucket and travelling, not idling. Say what ground it worked: a mini that dug ponds on a farm near Chepo has had a gentler life than a 20-tonne that broke rock for a subdivision in Arraiján. And say exactly where it stands: the buyer’s lowboy driver will ask whether a loaded truck can get down that road and turn round.