GHL130 light mowing head on a Unimog for RDW Łańcut

The Podkarpackie Provincial Road Authority (PZDW) has taken delivery of a second ROLMEX GHL130 light mowing head, intended to work with a hydraulic power arm mounted on a Mercedes-Benz Unimog special vehicle. The first machine of this type has been working since last season at RDW Jarosław, the second one goes to RDW Łańcut. The head was built in Kielce and matched to the carrier and to the arm the user already operates.

What was delivered to RDW Łańcut

The unit received the working head alone — the vehicle and the hydraulic power arm are already in service. The GHL130 design comprises:

• a body made of DOMEX400 steel,
• an adjustable front section that allows the head to be matched to the height and density of the vegetation,
• cutting of grass and bushes up to approx. 5 cm in diameter,
• an optional UltraCut rotor for grass mowing, with no blade mounting lugs.

The range of applications declared for this machine covers mowing the road right-of-way, flood embankments, drainage ditches and urban green areas.

Why a road authority needs a head on a power arm

Maintaining the road right-of-way means, in practice, working off the carriageway: slopes, counter-slopes, ditch bottoms, strips behind the barrier, brush at the junctions. A hydraulic power arm makes it possible to handle these places from a vehicle travelling on the carriageway or the verge, without driving the carrier down into the ditch.

The second reason is seasonal. The same carrier-and-arm pair works in spring and summer on mowing, and after the head alone is changed it moves on to other maintenance tasks.

How the head is matched to the job

Weight at the end of the arm

The most important limitation when selecting a head is the lifting capacity of the power arm tip. The data sheet of the GHL125 light mowing head gives a working width of 1.25 m, a weight of 270 kg and a shaft power of 68 HP; the manufacturer notes at the same time that mowing heads in larger sizes are made at the customer’s request. Low weight puts less load on the end of the arm, so the head also fits machines that will not carry heavier attachments. The excavator version of the same head is quoted at 280 kg without the bracket, with a requirement of 80 l/min and 200 bar — figures that have to be compared with the output of the carrier’s hydraulic system before a model is decided on.

Cutting diameter

The declared approx. 5 cm diameter sets the working range: grass, weeds and low scrub, that is the routine maintenance of verges, ditches and slopes. Thicker self-seeded growth and wood are a job for heavier attachments — the GH-120 or GH-130 flail head: 120 and 130 cm wide, weighing 270–340 kg and 280–350 kg respectively, dry wood up to 6 cm, and up to 11 cm with H360 FORESTAL rotating hammers, with a cutting shaft speed of 3000–3100 rpm and an additional inner shell made of HARDOX400 plate.

Rotor matched to the type of vegetation

The character of the head’s work is decided by the rotor and the blades or hammers mounted on it. UltraCut, with blades fixed on solid rings and no mounting lugs, is the solution for grass mowing. In the heavier GH heads the choice includes Precision ROTOR, UniversalROTOR2, T6 hammers and H360 FORESTAL rotating hammers — from precise grass mowing to shredding woody regrowth.

A head matched to the carrier already owned

In this delivery the carrier was a Unimog with a hydraulic power arm already fitted, so the head was built for the existing arm and vehicle. The alternative solution is a complete set with a tractor: the KR520 and KR600 power arm mowers have a reach of 5.6 m and 6.5 m, require a tractor with 100 HP and 110 HP of power, a minimum width of 200 and 220 cm and a weight of 4000 and 4500 kg, and the power given in the data sheet is 68 HP in both cases. They accept all working heads made by ROLMEX.

Outside the mowing season

Roadside and drainage ditches need not only mowing but also desilting. Instead of the mowing head, the same arm can carry the PR80 ditch cleaner: an 80 cm working disc, a weight of 300 kg, a required minimum oil flow of 110 l/min at 200 bar or 85 l/min at 300 bar, a working pressure of 220–240 bar and root cutting up to 10 cm. Fitting and removal take 3–4 minutes, and the machine is intended to work in the high ground moisture typical of autumn and spring.