Watch: picking stones the easy way

Based on the outskirts of Kells, Co Meath, in the village of Carnaross, Farrelly Brothers contracting is owned and run by Peter and Patrick Farrelly. Well known within local contracting circles, the Farrelly name is well established in the game, having taken over the business from their father in 1975.

The Farrellys offer a wide range of services alongside the typical agri-contracting duties, some of which include willow harvesting, site clearance, civil works, road maintenance and tree care up until more recent times. The diversity of the business is what ultimately led to the purchase of a stone picker.

“In 2007 we happened to be working on the new gas line which was being installed from Gormanston to Belfast. We had an issue with a tractor which was being fixed by Hanlons in Dundalk at the time and in the yard I spotted the Kivi-Pekka stone picker. It took my attention.

“At the time we were cleaning up after the gas line was installed. This involved a number of lads, usually four, picking stones by hand which everyone knows is no easy job. So, we got a demo of the Kivi-Pekka for a day and bought one having seen it work,” Peter explained.

At the time and today still, site clearance and tidying up after civil works such as motorway/gas line projects accounts for a large proportion of the Farrelly Brothers business, so the purchase of a dedicated stone picker seemed like a worthwhile investment. To date, the machine has worked as far away as Scotland as well as across Ireland, having picked stones for farm reseeding, football pitches as well as more unique locations, like at Dublin airport.

Pickup/intake

The machine’s design is similar to that of a baler. At the front there are two rotors fitted with tines which throw stones towards the centre of the machine. From here stones are guided into the lifting drum (like a baler’s pickup) which is fitted with five rows of large tines. Stones are then thrown into the hopper.

Within the range there are three machine working widths – 4m, 5m and 6m. Farrellys’ machine, like the rest sold in the country, is a 4m. Peter noted how a larger working width wouldn’t follow the ground’s contours as well and leave the machine a half or full metre higher in transport position. That said, the 5m and 6m machines come with a wider lifting drum with more tines to accommodate the increased working width and intake.

Rotors are raised and lowered via a single ram positioned vertically within a pendulum-type setup.

Each of the two 1.8m rotors is fitted with heavy duty hardened tines which Peter noted have worn very well considering the material they handle. Because these tines are welded to the rotor this leaves replacement quite a task.

The drive line is simple with a “T” gearbox suppling power to smaller gearboxes left and right. From here, a pulley fitted with three single belts transfers drive to each rotor. These belts are designed to absorb the shock of stones coming into contact with the rotors or if they jam the belt can slip. Peter said that this is rarely the case as the rotors can be easily raised up and away from the surface.

The outer side of each rotor is fitted with a depth wheel (similar to a pickup wheel). These are manually adjusted to change working depth. The hydraulic ram on the drawbar helps raise and lower the machine’s working height.

Lifting drum and hopper

Once stones are directed into the centre, they are then fed into the 400mm wide lifting drum. The drum is fitted with 18 large tines in total, across five rows. Interestingly, the number of tines per row differ and are configured three, four, four, three and four. Peter noted that the tines are the components subject to the most wear and tear. Last year, tines were replaced for the first time since 2007.

“They were well worn, one or two broke, it was like they lost their temper so we replaced the full set.” Each of these 45mm x 12mm tines is mounted with a rubber damper to help absorb shock while in operation. Peter explained how it is important that tines are not over-tightened on the rubber mount as they’ll break much easier. The drum is also belt driven which is powered off the same driveline as the right hand rotor. The three individual belts are fitted with an automatic nylon tensioner.

Underneath the lifting drum is a 40mm metal screen to allow any small stones to fall through. Smaller (30/35mm) or larger (50mm) screens can be specified.

After passing through the lifting drum, stones are then loaded into the hopper. The Kivi-Pekka’s high-tip design leaves it well able to tip straight into a dumper, on average a 12t dumper holds three full hoppers, Peter said. The floor of the stone hopper has a screen to allow any clay to fall through. There is also another screen on the back of the hopper to filter out clay while the hopper is being emptied.

The standard drum is designed to lift stones up to the size of a football at ease, although Peter said that on the rare occasion a large awkward-shaped stone may get wedged in between tine rows and block the drum, stopping it from turning. The lodged stones then have to be pried out. The Kivi-Pekka can be fitted with a hydraulically adjustable drum to accommodate larger stone sizes up to 50cm.

Verdict

Thirteen years on with the Kivi-Pekka, Peter feels that it was a good addition to the business.

“It’s hard enough now to get labour to drive machinery, never mind a team of guys to pick stones. Over the years we’ve got more use out of the machine than we originally thought we would.

“It’s a straightforward, simple machine. Apart from greasing three shafts and a few bearings, maintenance is minimal. All we’ve had to replace so far was the drum tines there last year. Other than that the machine hasn’t been touched.

“There’s really only two things to be aware of while using the machine, the first being to ensure PTO is in neutral when folding up the two rotors. If not in neutral, the shafts, if they are in the wrong position will not be able to move freely to fold and potentially do harm. The other thing to be aware of is to run the machine and make sure the hopper is completely empty before folding up. If it’s not empty a stone may similarly prevent the shafts from moving freely and cause damage.

“It’s an easy machine to drive. As little as 100hp would be capable. We find that best throughput is around 5km/h as the forward speed helps get the stones up into the machine. Typically we would lift 1-1.5ac/hr depending on conditions. An hourly rate proves most fair for everybody as the amount of stones really dictates throughput. We tend to charge €140/hr for the service.

As well as picking the stones, the rotors till the top of the ground nicely. In the drier weather it’ll work better. Ideally the hopper full of stones will be clean with no clay stuck to them at all. I’ve often seen stones used for land drainage straight out of the hopper.

“Although we pick stones for a few farmers that are reseeding, the main work for the machine is site clearance or tidying up after civil works. These sort of projects have seen us work the machine all across the country as well as Scotland. The major saving is the reduction in manual labour,” Peter explained.

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Specification

Model: Kivi-Pekka 4.

Working width: 4m.

Max stone size: 30cm (50cm optional).

Lift drum: 18 tines.

Hopper capacity: 2m3.

Power requirement: 70hp.

Weight: 4,000kg.

Tyre size: 560/60 R22.5.

Selling price: €40,000 plus VAT (£36,200 plus VAT). Watch the video here: