A KEANE EYE: Don’t roll over for anyone

The ROPS2 – a two-stage roll-over preventative system – may not quite prevent a roller from tipping, but it certainly makes as good an effort as you can expect, short of bolting it to a concrete plinth. Vibratory rollers are more susceptible than most machines when it comes to risk of roll-over. It comes from the fact that when they vibrate, the drum actually loses contact with the ground. If the roller is on a side slope then the roller tends to skip sideways as it leaves contact with the ground. A further risk is if the ground at the edge of an embankment starts to collapse while it is being compacted. This is more than theory: vibratory rollers have a track history of rolling over, sometimes with fatal results. This prospect was of sufficient concern for Abigroup and Leighton to approach manufacturers for a solution to the problem while they were working together on the M7 motorway. Conplant was the one party to show an interest in developing a solution to the problem, and quickly had a prototype and a tilting test bed ready for testing. The parties agreed that the solution should be a two-stage process, with a tilt sensor on the front drum activating a warning light and audible alarm in the cabin when the drum approaches a potentially dangerous angle. This warning provides the operator with time to react to the situation. The second stage of the system turns off the vibration if the drum tilts a further one to two degrees, reducing the risk of roll-over without the need for intervention from the operator. This isn’t recent news – the ROPS2 began making waves two years ago. So why did it feature heavily on the Conplant stand at the recent Australian Construction Equipment Expo, ACE?ROPS2 is now a mature product fitted to over 170 rollers in the Conplant hire fleet, and the system has a combined 80,000 hours of operation behind it to show it is accurate and reliable. It may seem like a simple thing, to put a tilt sensor on a roller and hook it up to an alarm. However it took quite a bit of thought to get it to the stage where Conplant was comfortable that the components used were accurate and reliable, so that they could be relied upon to provide protection for the life of the machines they were fitted to. Along the way, Ammann has been sufficiently impressed enough to now offer ROPS2 as a factory-fitted option. It’s good to see also that some local contractors are insisting on ROPS2 being fitted to vibratory rollers used on their projects, and are considering its fitment to other types of plant, such as articulated dump trucks. Articulated plant items can be at risk because the chassis section containing the cab may be stable and give the operator no sensation of danger when the chassis section at the other end of the articulation joint can be at the point of rolling. The ROPS2 system can overcome this problem if the tilt sensor is fitted to that chassis section, and does not rely on the operator to sense danger. For Conplant, developing ROPS2 wasn’t about the money – it is doubtful it will ever fully recover its investment in ROPS2. However, the system is something that is of benefit to the industry as it addresses a real safety issue that has not, to date, been addressed at manufacturer level. While the bulk of the units thus far are fitted to rollers in the Conplant hire fleet, there are no plans to confine its use to either Ammann rollers or in-house hire machines. The solution is offered to the industry at large. The only proviso is that stability tests need to be performed on each of the different model of machine that the system is fitted to, to determine the most appropriate tilt angles for triggering the two-stage system response to the tilt hazard. Conplant deserves big kudos for investing significant resources into finding a solution to this problem, and for having that solution recognised internationally.

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