Roll over protection excavator cabs become a reality

ISO certified excavator ROPS cabs are coming for excavators. Mark Cherrington reports

It's been a long time coming, but certified ROPS cabs on excavators are a reality following the recent release of a standard, 3041 ISO 12117-2: 2008, which sets out laboratory tests and performance requirements for protective structures on excavators weighing between 6 and 50tonnes.

In addition, an update to the EU's Machinery Safety Directive (MSD), 2006/42/EC, which took effect at the end of 2009, brought in a number of changes, including a requirement for crawler excavators in the 10 to 50tonne range to provide added operator protection in the event of a machine rollover. While this does not specifically require the use of the new ISO standard, at least one manufacturer, 395 Caterpillar, has decided to adopt the standard on its excavators to ensure compliance with the directive.

For many years, excavators - unlike most other items of earthmoving and construction equipment - have been exempted from the requirement to have a ROPS (roll over protection structure). There are a number of reasons why this has been the case.

To begin with, the structural design of an excavator has made it quite a challenge to develop a strong enough 'platform' on which to mount a ROPS, and which is able to withstand the forces on a cab and its supporting platform in the event of a rollover. An excavator is not like a dozer or truck, where the cabin sits on the main body of the machine, and simply has to be robust enough to withstand the weight of the machine if it rolls over.

On an excavator, the 'platform' in the front left-hand corner of the machine where the cab is mounted has to be able to support the entire weight of the machine, as well as provide structural integrity to the ROPS so that the operator is protected. Over the years, excavator manufacturers have carried out a lot of R&D work to come up with a platform and cabin structure that can meet the high safety requirements of a ROPS standard.

Other reasons for a lack of an excavator ROPS standard probably include long-standing industry attitudes. For many years, it was felt that due to the nature of their work, and their limited load-and-carry duties, excavators were at fairly limited risk of roll over.

However, with excavators increasingly used on steep sites and rough terrain, and with an ever-growing range of attachments, the risks of rollover have been increasing; the latest advances in design and materials technology have meant development of an excavator ROPS standard was now feasible. At least three excavator manufacturers - Caterpillar, 6512 Hitachi and 436 Komatsu - now offer cabs for some or all machines within their 6 to 50tonne ranges that comply with the new standard, although compliance with the standard has not yet been mandated by authorities in all jurisdictions. However, in some markets, these manufacturers have already begun promoting their ROPS compliance, primarily as a marketing advantage.