Roll Over
Protection Structure (ROPS) refers to operator compartment
structures (usually cabs or frames) intended to protect
equipment operators from injuries caused by vehicle overturns or
rollovers.
Commonly found on heavy equipment (i.e. tractors) used in
construction and agriculture, ROPS structures are defined by
various regulatory agencies, including the US Occupational
Safety and Health Administration (OSHA. The regulations include
both a strength requirement as well as an energy absorption
requirement of the structure. Some dump trucks add a protrusion
to their boxes that cover the operators compartment for ROPS
purposes.
In the US, ROPS designs have to be certified by a Professional
Engineer, who will normally require a destructive test. The
structure will be tested at a reduced temperature (where the
metal is more brittle), or fabricated from materials that have
satisfactory low temperature performance.
The National Institute for Occupational Safety and Health (USA)
believes that ROPS and proper seatbelt use on tractors can
eliminate nearly all fatalities caused by tractor and lawn mower
overturns. (Without a seatbelt, the rider may be thrown from the
tractor during the overturn, and thus left unprotected by the
ROPS). A recent Cochrane Systematic Review confirmed that in one
Swedish study there was evidence that legislation mandating ROPS
on new tractors decreased the fatality rate immediately and
further reduced the rate over time.
Some tractor operators have raised concerns about using ROPS in
low-clearance environments, such as in orchards and buildings.
In response, NIOSH developed an Automatically Deploying Rollover
Protective Structure (AutoROPS) which stays in a lowered
position until a rollover condition is determined, at which time
it deploys to a fully extended and locked position. It is
currently working with manufacturers to streamline the
commercialization of this technology.
Some automobile models have begun to adopt the phrase,
substituting system for structure in the ROPS acronym, notably
the Volvo C70 convertible models, and Jaguar XK. Their ROPS
structures consist of two pyrotechnically charged roll hoops
hidden behind the rear seats that will pop up in the case of a
roll-over to protect the occupants. If the roof is up, the
system will still work, in effect shattering the rear window at
the same time.