Monday, 30 October 2017 11:53

Keeping hedges nice and tidy

Written by  Mark Daniel
Maintaining shelterbelts and hedges is the domain of the JCB cutter. Maintaining shelterbelts and hedges is the domain of the JCB cutter.

Vineyards and orchards typically have vertical shelterbelts to ensure crops do not succumb to the effects of wind.

Maintaining these belts, which can be 12m high, is the domain of specialised machines built as one-offs or mounted on heavily modified tractors or telescopic handlers.

Cutting Edge Shelterbelt Trimming and Mulching has been operated by Dale Hunt for about 13 years, clocking up 14,000 hours on a telehandler-based machine in an area from Pukeohe in the south to Omaha Beach to the north.

When it came time to replace his machine, Hunt was drawn to the new JCB 4220 Fastrac, a high- speed mobility tractor built in the UK and known for its capabilities in carrying loads at the front and rear and a load platform behind the cab.

The Fastrac ticked all the boxes required of a new machine: a larger cab for more operator comfort, more power to deliver greater hydraulic flow, a higher road speed to reduce travel time between jobs, larger tyre equipment for poor off-road conditions and a good four-wheel system for increased manoeuvrability.

Having committed to take the first 4220 to arrive in NZ, Hunt gave the task of building the boom and cutter-head assembly to a specialised fabricator near his home in north-west Auckland; he created the machine we see today. The seven months taken to fabricate and attach the machine is testament to clever engineering solutions learnt from the previous machine, but also using specialised materials to achieve the desired effect.

The three-stage boom weighs about 2.5 tonnes, has a two-stage lift system and mounts to a central slew-post that in turn attaches to a substantial box-section subframe that runs under the rear axle to an area under the bell housing. To help improve balance and stability, the box section is filled with metal punchings to add weight and to keep the centre of gravity low.

With a vertical reach of nearly 18m, the 3.2m cutter-head, carrying three circular saw-like blades, can deal with the highest shelterbelts in both the vertical and horizontal planes. The blades rotate at 1300rpm while the cutter-head itself can operate in three planes on either side of the tractor. The ability to rotate 65 degrees about the centre-post and to be able to lean 15 degrees from vertical means that profiles of any shape can be cut with ease.

The overall weight of the boom requires that both rear wheels of the tractor are ballasted with 300kg wheel weights, while a cleverly designed, 400kg counterweight can be swung to either side of the centre-post when cutting laterally, particularly when reaching across drains.

The cab is heavily modified using a 10mm thick bisalloy steel roof plate which in turn houses a viewing window manufactured from a sandwich of two pieces of 10mm toughened glass separated by a 3mm piece of laminate.

Meanwhile, the hood and frontal areas carry guards, bash-plates and belly pans made from 6mm steel plate.

Power is delivered by a 6-cylinder, 220hp SisuPower engine that in turn runs a Fendt-derived CVT transmission which delivers stepless speeds in either direction up to 60km/h.

Braking is by an external disc set-up on each corner of the machine.

The key to the business end of the machine is hydraulic flow, so clever plumbing sees the tractor’s own hydraulic system being used to control all the boom functions, while a PTO-driven pump powers the cutter-head, using its own reservoir and cooling pack.

To date, the machine has exceeded all expectations for comfort, with cab noise as low as 74dBa, improved visibility – the drivers sits higher than in the old machine – stability and ease of road travel.

One stand-out feature is the TrueTrak steering system that allows tighter turns as the machine is entering or exiting work in the orchard.


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