Video: The mesmerizing motion of walking "spider" excavators
These little-known machines have to rank as some of the greatest sandpit toys in history. Walking spider excavators offer an extraordinary range of capabilities through their articulating, extending legs, stabilizers, tilting wheels, and buckets.
To be clear, walking excavators are not new. Not by a long way. But we hadn't run across them before, so we thought you might not have either, and they're a wonderful celebration of hydraulic machinery that's mesmerizing to watch in action. Skip to the video at the bottom if you're feeling impatient, and you'll see what I mean.
Indeed, these things have been around in some form or another since 1966, when Josef Kaiser built his first walking excavator at his friend Ernst Menzi's factory. The two didn't stay friends for long; according to Kaiser's official history, Menzi quietly pinched the idea soon after the first prototype was demonstrated, and started selling it as the Menzi Muck, while Kaiser started manufacturing them with his own company. More than 50 years later, the Kaiser and Menzi companies both continue to develop and sell these remarkable machines.
Walking excavators were originally designed to operate on the extreme gradients and difficult terrain of the Swiss Alps, where regular wheeled and tracked excavators could be flat-out dangerous. They started out with a simple single-axle pair of wheels on the back, and a pair of set feet on the front, getting around by using the hydraulic arm and bucket to lift the legs and drag the wheels around.
By the early 1970s, they began putting the wheels and stabilizer feet on their own hydraulic arms, making them capable of sitting level on a wide range of gradients and giving them extra leverage, grip and stability for lifting and ripping tasks. By the late 70s, telescoping hydraulics became available, meaning those legs and spider-wheels could stretch out even further.
Today's spider excavators are magnificent beasts in motion. The legs extend, retract, lift, lower and articulate at the hip, knee and ankle joints. Hydrostatically-powered wheels, steel claw mountain stabilizers or individually driven caterpillar tracks on the ends of the legs can each be tilted, the cabin is fully rotating, and the powerful excavator booms can dish out more force than tracked excavators twice their weight. They can also scale slippery, muddy slopes no conventional excavator would dream of attempting, and they can straddle holes and gaps, climb over obstacles, and basically address a wider range of geographies and topographies than any other excavator.
They are not, however, hugely popular – or even particularly well known, because for 99% of jobs, regular, cheaper tracked or wheeled excavators do the job just fine. Their monstrous hydraulics require heavy and regular maintenance, adding to the operating cost. And as you might imagine, it's an absolutely epic challenge to learn to drive a machine with such massively broad and unusual capabilities. As one Australian owner/operator quipped to Machines4U, at least you don't need to worry about them getting stolen.
But when it's time for critical work in extreme environments, spider excavators can tackle the jobs nothing else can get to. And if you get a chance to see one showing off for a demonstration at an expo, you're in for a mechanical treat, the sort of thing that'd make your kid want to go out in the back yard and play with a hard hat on. We've filled the gallery with a selection of absolutely epic photos, and we've chopped together some fun clips from Kaiser and Menzi into the video below. Enjoy!