ROPS Information you may not know
To improve the safety of heavy machinery operators in construction and forestry, Occupational Safety and Health (OSH) standards require that operator protective structures be fitted to the machines.
Commonly referred to ROPS, an acronym for roll-over protective structures, operator protective structures also include the following:
- tip-over protective structures (TOPS)
- falling-object protective structures (FOPS)
- operator protective structures (OPS) ie grills to prevent objects entering the cabin.
Outside of New Zealand, it is standard practice to carry out physical testing of ROPS Frames for certification according to International Safety Standards.
As ROPS are developed to absorb energy on impact – they are one shot defined. Due to the lower volumes of ROPS in New Zealand, and the “one-off” nature of the New Zealand market, it is cost prohibitive to physically test every design. Because of this, New Zealand has developed its own code – Approved Code of Practice for Operator Protective Structures on Self-Propelled Mobile Mechanical Plant (ACoP) - to ensure that ROPS meet expected safety requirements.
A cab frame, which is locally designed and built to New Zealand’s ACoP, is recognised as a Cabin Operator Protective Structure (COPS).
The Department of Labor Occupational Safety and Health Service introduced the current ACoP in 2001 and since then have had concerns over some engineering design practices that purported to satisfy the requirements of its ACoP.
The best engineering design method to ensure safety
JB Attachments works with an experienced engineering consulting firm using Finite Element Analysis (FEA) to ensure that its ROPS strictly conform to ACoP and are recognised COPS. FEA is based on sophisticated computational modeling and stress testing techniques. This provides an accurate method of determining how a ROPS would hold up in the event of an onsite roll, without physically testing it.
FEA engineering design techniques allow for a more efficient design than those built relying on less accurate hand calculations. A ROPS engineered using hand calculations would effectively have to be overbuilt – with a much heavier frame - to achieve a comparable level safety with a ROPS designed using FEA techniques. Hand calculation techniques are also less accurate in assessing the true behavior of a frame and its ability to deform safely to absorb the energy of a roll.
It is the shortcomings of ROPS frames engineered using hand calculations that has caused OSH concern because these substandard analysis techniques do not meet ACoP.
If your machine is working on a site where there is a risk of a roll then OSH regulations require that the machine have a ROPS fitted. They also require that the ROPS has a current certification. The expiry that engineers stipulate on machines varies depending on a number of reasons but is generally around 5 years. The expiry is in place so that regular adequate inspections are done to ensure the frame’s integrity for future use.
JB Attachments can assist you with having your ROPS frame and cab recertified. For recertification it is required that the machine be inspected by the original designer or delegate. Often supplying specified photos of the ROPS and attachment in conjunction with a thorough inspection by a competent person is adequate for recertification.
Recently, new models of excavators are being developed with sufficient cab structures to meet the level of safety expected by OSH. However, robustness of these new machine cabs is not sufficient to meet forestry industry safety requirements and will still need a ROPS - but they will be acceptable for use on construction sites. Older machines will also still be required to have a ROPS.
JB Attachments specialises in modifying excavator cabs for special purposes. Examples of cab alterations include bush-rigging, most suited to forestry applications to protect the machine cab and also high-rise cabs to enhance the performance and operation of your machine. Any cab alterations can be specially fitted with a JBA ROPS.
Chris Deakin - TSV Consulting
IPENZ Practice Note 12 – Operator Protective Structures.