What is a Roll Over Protection Structure (ROPS)?

A Roll Over Protection Structure (ROPS) is a reinforcement member(s) installed into, or onto a vehicle with the intention of protecting the vehicles occupants in the event of a roll over accident.

The primary intent of a ROPS is to limit the crushing and deformation of the vehicle roof and cabin structure during a roll over accident. This ensures that the vehicle occupants are provided with an adequate amount of survival space which reduces the risk of head, neck/spinal, and upper torso injuries, ultimately preventing death.

Why is a ROPS needed?

Modern production vehicles are designed to meet specific safety standards centred around improving occupant safety. These include seat belts, Supplemental Restraint Systems (Airbags), door latch burst strength, braking performance, and side/frontal impact crumple zone/crash strength. However, these safety features are focused mainly around highway use of sedan type vehicles where roll over is a low occurrence incident.

In contrast to that of a sedan, light commercial and four-wheel-drive vehicles have a much higher centre of gravity (CG). Combined with this, new levels of ride comfort, power, and quietness make it far easier to travel at higher speeds than the equivalent type of commercial vehicle in the past.

At highway speeds, modern commercial vehicles have a much higher risk of roll over type accidents in situations where evasive or correct steering action is needed. Added to this, the vehicles tendency to carry higher loads reduces the driver’s ability to slow the vehicle before encountering such circumstances.

Roll Over Propensity

The most common scenario of a rollover accident occurs when quick evasive or corrective steering action is required, and taller and heavier vehicles are more likely to ‘trip over’.

A vehicles rollover propensity or ‘the tendency of a vehicle to roll’, can be calculated through a simple mathematical formula of T/2H (where ‘H’ = height of the Centre of Gravity of the vehicle; and ‘T’ = vehicle track width). Put simply, the higher the vehicle’s centre of gravity, and the narrower the track width, the greater the chance of a rollover accident occurring.

A very important and often overlooked aspect to this formula, is that the vehicle’s occupants and payload actually raise the vehicle’s Centre of Gravity, and can play a big part in the rollover likelihood. Inline with this, having additional mass up high on the vehicle, like that represented by most external ROPS, will result in a higher propensity to rollover. It would seem in conflict to produce a type of ROPS structure that gives the vehicle a higher propensity to rollover.

Research conducted by the National Transportation Safety Board in the USA (NTSB/SR-02/03 PB2002-917005) on the rollover propensity of 15-passenger vans directly relating to occupancy level concluded that, 15-passenger vans with 10+ occupants (despite the 15-passenger rating) had 3 times the rollover ratio to that with fewer occupants, thus evidently proving the importance of occupant/load weight on the roll over propensity of a vehicle.

Different types of ROPS

The common two types of ROPS are internal or external structures. Internal ROPS (as produced by Brown Davis) are designed to fit inside the cabin space of the vehicle mounting to its floor pan. On the other hand, the external types are designed to fit around the outside of the vehicle cabin mounting to the chassis rails under the vehicle, or behind the cabin as part of the rear tray sometimes extending over the cabin roof.

Internal

  • Internal mounting supports original roof structure
  • Suits all vehicle types; wagon, utility, bus
  • Less mass for a stronger structure
  • Less effect on height of Centre of Gravity
  • Car appears externally standard
  • Not subject to environmental wear and tear
  • Slight compromise on entry/exit of some vehicles
  • Easy to transport in kit form

External

Mounted into the tray of utilities or surrounding the outside of a cabin structure. They significantly add to the height of the vehicle’s centre of gravity.

Tray type:

  • Limited by tray or its mounts onto chassis (can be torn off leaving occupants unprotected)
  • Reduces load space and load mass
  • Prone to damage from load being carried in tray

Around cabin type:

  • Limited by chassis mounting
  • Prone to damage and environmental wear and tear
  • Significantly heavier structure than other types
  • Increases propensity to roll over

Following on from the Rollover Propensity information, a ROPS weight and its location are very important factors to consider, as they can contribute to the rollover propensity ratio of a vehicle. A Brown Davis internal ROPS kit weighs between 40-50kg for a 4-point dual cab type vehicle and up to 80kg for a 4WD wagon. With them installed inside the cabin, they have little affect on the Centre of Gravity of the vehicle, arguably lowering it. In contrast, some external type ROPS designs currently on the market fitted on the back of utility/pick up type vehicles weigh up to as much as 370kg. Sitting as high up on the vehicle as they do, they would increase the height of the centre of mass and hence, the rollover propensity ratio of the vehicle – thus increasing the chance of rollover compared to internal designs.

It would seem illogical to disregard the weight of a roll over protection structure design, that ultimately increases the chance of a roll over taking place.

ROPS Technical Specifications and Information

ROPS Design Features

All Brown Davis ROPS kits are designed as bolt in systems to suit individual vehicles. All components are carefully prototyped on a test vehicle to ensure critical tolerances are achieved for a neat fit and optimum protection. Ensuring maximum occupant space is obtained, and entry/exit considerations are maximised, is paramount in each design. Below are some of the key design features of each Brown Davis ROPS unit.

Footplates/Brackets/Backup Plates: Computerised laser cutting and folding of all foot plates, brackets and back up plates ensures perfect jig and vehicle fitment, allowing Brown Davis to consistently replicate each ROPS with tight tolerances. Folding to stiffen all mounting plates is part of the engineering thoroughness of Brown Davis ROPS designs.

Tube work: As key components to the ROPS structure, the hoops and side bars are a main focus of the production. Each hoop and side bar is bent on the latest CNC mandrel bending machines to produce precise bend angles, and also consistent replication of each ROPS unit. Tooling has been specially produced to ensure the bend radius (145mm centreline for 45.5mm O.D tube) is greater than 3 times that of the tube diameter. Mandrel bending leaves minimal compression of the tube through the bend, and thus maintains the maximum tube section. Both of the above enhance the ROPS assemblies overall structural strength.

Brown Davis Rollbar Joiners (patent pending): After years of constant development and testing earlier evolutions, Brown Davis have reached a near perfect solution to the bolt in/kit style assembly, while still satisfying and/or exceeding the tube strength specifications. These joiners have set the bench mark for internal ROPS design. Each item is CNC machined to give consistent assembly of components with tight tolerances. Clever design incorporates recessed bolt heads leaving only a smooth round surface with no protrusions, ensuring there is no risk of injury from upper body contact. This captive thread design also allows tight fitment of the ROPS inside the vehicle cabin to maximise occupant space. Internal steel locating dowels which resist sheer loading, eliminate the possibility of the bolts sheering when forces at 90 degrees are applied to the joiner. Testing of the roll bar joiners has confirmed that they are stronger than the tube itself, in both bending and tensional loads.

Brown Davis ROPS Material and Component Specification

Brown Davis Automotive uses only the highest grade of materials in the production of every ROPS. The listing below specifies the grading and specification of all components.

  • 350 MPa Cold Drawn high tensile steel tubing – 44.5mm O.D. x 2.6mm wall & 38.1mm O.D. x 2.6mm wall
  • 4mm mild steel footplate and brackets, 3mm mild steel back up plates (zinc plated)
  • CNC Machined 4140 steel rollbar joiners – Unbrako grade 10.9 high tensile cap screws
  • Welding to Australian Standard – AS1554
  • Grade 8.8 high tensile zinc plated fasteners
  • Head impact padding – Specially designed offset, closed cell, Polyethylene (PE) foam 60kg/m3
  • Satin black powder coat finish

Brown Davis ROPS Physical Testing

Developed as part of the Brown Davis physical testing process in consultation with third party specialist engineers, Brown Davis conducts in house testing with a specially designed test rig developed to replicate very specific roll over loads. The test rig has the capacity to produce a crushing force in excess of 20 tonnes in the vertical axis. Each ROPS unit can be rotated and fixed in many positions, in order to apply load to specific area’s of a ROPS structure, from any angle. The data acquired from such testing is used to correlate and validate data obtained in FEA (Finite Element Analysis) testing.

The Brown Davis ROPS testing rig is equipped with sophisticated measuring and data logging instruments. These highly accurate data acquisition components allow even the most minute distortions and deflections in the structure to be measured and recorded at a rate of 100 cycles per second. Once collected, the data can be be correlate and graphed accordingly to confirm prior FEA testing and to ensure that the model and prototype conclude the same outcomes.

ROPS Design Elements

The design of any ROPS needs to take into consideration two very important aspects; Structural mount points and Ergonomics. As each vehicle cabin space can be vastly different, it is important to assess and design a specific solution to each vehicle, rather than a ‘generic’ design applied to all. Although the visual concept remains similar, each ROPS can vary greatly in size/shape and mounting locations.

Structural mount points: Critical to the effectiveness of each ROPS are the locations where the ROPS will mount to the body of the vehicle. Careful consideration is given to locating them at well supported floor-pan and pillar areas able to withstand the forces required by the ROPS structure during a roll over accident. Often, the standard captive points for seat belts, seat mounts and other components are already well engineered by the manufacturer to sustain such loads and can be utilised for mounting points. However, where this is not possible, or where it is not safe to do so, alternative points are tested and new solutions found.

Ergonomics: As with any form of Roll Over Protection, there is often a minor compromise with space in the cabin area. Routing tube work and side bars becomes an intricate exercise to find the best possible combination of strength and safety. We maintain a satisfactory comfort level, by not impeding into occupant seating space more than absolutely necessary. In most cases comfort is not hindered at all, however some vehicle cabin designs limit the options available for ROPS mounting and tube positioning, and therefore Brown Davis search for the best overall compromise for each vehicle. A poorly designed ROPS can in many ways become more of a safety risk, than a benefit if badly designed.

ROPS 3D CAD design
The use of 3D CAD modelling software has become increasingly beneficial to research and development work in almost all manufacturing industry. Brown Davis takes full advantage of these high tech techniques, to design and model all components prior to any ROPS going to prototype testing or final production. From the footplates, to the rollbar joiners, each component is drafted into a workable 3D model. This in turn gives much greater scope for development and testing any new concepts and ideas. Combined with Finite Element Analysis (FEA), prototypes and testing can be thoroughly scrutinised in great detail.

Finite Element Analysis (FEA)

Finite Element Analysis (FEA) offers a detailed visualisation of where ROPS structures bend or twist, indicating the distribution of stress. This allows designs to be created, optimised and finalised in 3D before the design is manufactured. FEA in ROPS creation has become a very useful tool, with its ability to allow insight into real world outcomes prior to destructive testing of actual prototypes. The resulting stress and deformation can be measured for simulated rollover loads from nearly any axis, and therefore each component and structure can be re-designed or modified accordingly, until an effective computer model meets the load levels Brown Davis Automotive deem acceptable.

Brown Davis incorporates both physical (destructive testing), as well as computer based analysis. Physical testing is carried out to confirm FEA results and substantiate the computer model. Complex motorsport ROPS produced by Brown Davis Automotive have been compared against FEA models and revealed a result within 5% (FIA approval cannot be issued without such FEA proof for ROPS in motorsport).

It is this combination of critical data that enables very efficient progress of each design, and ultimately produces a superior product, providing the maximum roll over protection achievable.

Each ROPS design produced by Brown Davis Automotive comes with an independent third party consultant engineering report, completed by one of the leading specialists in the field. (Click the report page below to view Ford Ranger ROPS Report to see an example)

Click here for Ford Ranger Dual Cab FEA report

TOYOTA

Make  Model  Series  Part Number  Points Pillars & Braces Cargo Barrier Fitting Hours 
TOYOTA  HIACE COMMUTER BUS – 10 SEATER ROPS-THIC10-V6 6-POINT CONSTRUCTION  B, C, & D PILLAR  AVAILIBLE- CB-THIC10-V6 4.5
TOYOTA  HIACE COMMUTER BUS – 14 SEATER  ROPS-THIS14-V6 6-POINT CONSTRUCTION  B, C, & E PILLAR  N/A 4.5
TOYOTA  HILUX DUAL CAB 2005 ONWARDS – HEAVY DUTY NON SIDE CURTIAN AIR BAG COMPATIBLE  ROPS-TH05-D4 4-POINT CONSTRUCTION  B & C PILLAR  N/A 3
TOYOTA  HILUX DUAL CAB 2005 ONWARDS – SIDE CURTIAN AIR BAG COMPATIBLE  ROPS-TH05AC-D4 4-POINT CONSTRUCTION  B & C PILLAR  N/A 3
TOYOTA  HILUX EXTRA CAB 2005 ONWARDS – SIDE CURTAIN AIR BAG COMPATIBLE  ROPS-TH05AC-E4 4-POINT CONSTRUCTION  B & C PILLAR – DIAGONAL SIDE BRACES IN REAR  N/A 3
TOYOTA  HILUX SINGLE CAB 2005 ONWARDS-SIDE CURTAIN AIR BAG COMPATIBLE ROPS–TH05AC-S4 4-POINT CONSTRUCTION  B PILLAR DUAL HOOP CONSTRUCTION WITH FRONT LEGS  N/A 2.5
TOYOTA  LANDCRUISER 75 SERIES UTE/TRAY ROPS-TL75-S4 4-POINT CONSTRUCTION B & C PILLAR N/A 3
TOYOTA  LANCRUISER 75 SERIES WAGON ROPS-TL76-W6 6-POINT CONSTRUCTION  B & C PILLAR REAR BRACES YES 4
TOYOTA  LANCRUISER 76 SERIES WAGON ROPS-TL76-W8 8-POINT CONSTRUCTION  A, B & C PILLAR REAR BRACES  YES 5
TOYOTA  LANCRUISER 78 SERIES TROOP – UP TO 2007 ROPS-TL75/78-T6 6-POINT CONSTRUCTION  B, C, & D PILLAR YES 4
TOYOTA  LANCRUISER 78 SERIES TROOP – UP TO 2007 ROPS-TL75/78-T8 8-POINT CONSTRUCTION  A, B, C, & D PILLARS YES 5
TOYOTA  LANDCRUISER 78 SERIES TROOP – 2008 ONWARDS WITH FRONTAL AIRBAGS ROPS-TL78-T6 6-POINT CONSTRUCTION  B, C, & D PILLARS YES 4
TOYOTA  LANCRUISER 78 SERIES TROOP – AMBULANCE WITH SIDE DOOR (C PILLAR HOOP MOVED REARWARDS BY 150 MM) – 2008 ONWARDSWITH FULL FRONTAL AIRBAGS  ROPS-TL78-T6A 6-POINT CONSTRUCTION  B, C, & D PILLARS YES 4
TOYOTA  LANDCRUISER 78 SERIES TROOP – 2008 ONWARDS WITH FRONTAL AIRBAGS ROPS-TL78-T8 8-POINT CONSTRUCTION  A, B, C, & D PILLARS YES 5
TOYOTA  LANDCRUISER 78 SERIES TROOP – AMBULANCE WITH SIDE DOOR (C PILLAR HOOP MOVED REARWARDS BY 150 MM) – 2008 ONWARDSWITH FULL FRONTAL AIRBAGS  ROPS-TL78-T8A 8-POINT CONSTRUCTION  A, B, C, & D PILLARS YES 5
TOYOTA  LANCRUISER 79 SERIES UTE/TRAY – INCLUDING FRONT AIRBAG MODELS ROPS-TL79-S4 4-POINT CONSTRUCTION A & B PILLARS N/A 3
TOYOTA  LANCRUISER 79 SERIES DUAL CAB – INCLUDING FRONTAL AIRBAG MODELS  ROPS-TL79-D4 4-POINT CONSTRUCTION  A & B PILLARS N/A 3
TOYOTA  LANDCRUISER  100 SERIES WAGON – 5 SEAT CONFIGURATION  ROPS-TL100-W6 6-POINT CONSTRUCTION  B & C PILLARS YES 4
TOYOTA  LANCDCRUISER  200 SERIES WAGON – SIDE CURTAIN AIR BAG COMPATABLE – (5 SEAT USE OF VEHICLE ONLY)  ROPS-TL200AC-W6 6-POINT CONSTRUCTION AND REAR SIDE BRACE  B & C PILLARSAND REAR SIDE BRACE BARS  YES 4.5
TOYOTA  PRADO 120 SERIES WAGON – 5 SEAT CONFIGURATION  ROPS-TP120-W6 6-POINT CONSTRUCTION  B & C PILLARS AND REAR SIDE BRACE BARS YES 4
TOYOTA  PRADO 150 SERIES WAGON – SIDE CURTAIN AIR BAG COMPATABLE – (5 SEAT USE OF VEHICLEONLY)  ROPS-TP150ac-W6 6-POINT CONSTRUCTION AND REAR SIDE BRACE  B & C PILLARS AND REAR SIDE BRACE BARS YES 4.5

 

 

NISSAN

NISSAN NAVARA D22 DUAL CAB  ROPS-NND22-D4 4-POINT CONSTRUCTION    N/A 3
NISSAN  NAVARA D40 DUAL CAB  ROPS-NND40-D4 4-POINT CONSTRUCTION    N/A 3
NISSAN  NAVARA  D40 DUAL CAB – SIDE CURTAIN AIR BAG COMPATIBLE ROPS-NND40AC-D4 4-POINT CONSTRUCTION  B & C PILLAR  N/A 3
NISSAN PATROL GU SINGLE CAB  ROPS-NPGU-S4 4-POINT CONSTRUCTION  B PILLAR DUAL HOOP CONSTRUCTION WITH FRONT LEGS  N/A 3
NISSAN PATROL GU WAGON – 5 SEAT ONLY  ROPS-NPGU5-W6 6-POINT CONSTRUCTION  B & C PILLARS WITH REAR SIDE BRACE BARS  YES 4

 

 

MITSUBISHI

MITSUBISHI TRITON L200 DUAL CAB 2006 ONWARDS ROPS-MTML200-D4 4-POINT CONSTRUCTION    N/A 3
MITSUBISHI TRITON ML DUAL CAB AUTO 2006 – LATE 2010 ROPS-MTML-DA4 4-POINT CONSTRUCTION    N/A 3
MITSUBISHI TRITON ML DUAL CAB MANUAL 2006 – LATE 2010 ROPS-MTML200-DM4 4-POINT CONSTRUCTION    N/A 3
MITSUBISHI TRITON MN DUAL CAB LATE 2010-2012 ROPS-MTMN-D4 4-POINT CONSTRUCTION    N/A 3
MITSUBISHI TRITON MN DUAL CAB LATE 2010-2012 ONWARDS ROPS-MTMN-D4LS 4-POINT CONSTRUCTION    N/A 3
MITSUBISHI TRITON MN DUAL CAB 2012 ONWARDS – SIDE CURTAIN AIR BAG COMPATIBLE  ROPS-MTMNAC-D4LS 4-POINT CONSTRUCTION    N/A 3
MITSUBISHI TRITON MN EXTRA CAB LATE 2010 – ONWARDS – SIDE CURTAIN AIR BAG COMPATABLE  ROPS-MTMNAC-E4 4-POINT CONSTRUCTION    N/A 3

 

 

FORD

FORD COURIER DUAL CAB 1999-2006 ROPS-FC9-D4 4-POINT CONSTRUCTION    N/A 3
FORD  RANGER  2007-2011 SINGLE CAB  ROPS-FR07-S4 4-POINT CONSTRUCTION    N/A 2.5
FORD  RANGER  2007-2011 EXTRA CAB ROPS-FR07-E4 4-POINT CONSTRUCTION  DIAGONAL SIDE BRACE BARS N/A 3
FORD RANGER  2007-2011 DUAL CAB  ROPS-FR07-D4 4-POINT CONSTRUCTION    NO  3
FORD  RANGER  PX 2011-ONWARDS DUAL CAB – SIDE CURTAIN AIR BAG COMPATIBLE  ROPS-FRPXAC-D4 4-POINT CONSTRUCTION    N/A 3.5
FORD RANGER  PX 2011-ONWARDS DUAL CAB – HEAVY DUTY – NO SIDE CURTAIN AIR BAG COMPATIBLE  ROPS-FRPX-D4 4-POINT CONSTRUCTION   N/A 3.5
FORD RANGER  PX 2011-ONWARDS EXTRA CAB – SIDE CURTAIN AIR BAG COMPATIBLE  ROPS-FRPXAC-E4 4-POINT CONSTRUCTION    N/A 3.5
FORD RANGER  PX 2011-ONWARDS SINGLE CAB – SIDE CURTAIN AIR BAG COMPATIBLE  ROPS-FRPXAC-S4 4 POINT CONSTRUCTION   N/A 3.5
FORD EVEREST WAGON ROPSFEV5-W6 5 SEAT 6 POINT CONSTRUCTION B, C&D PILLARS YES 5
FORD EVEREST WAGON ROPSFEV7-W6 7 SEAT 7 POINT CONSTRUCTION B, C&D PILLARS NO  5

 

 

MAZDA

MAZDA BT50 2007.2011 DUAL CAB ROPSFRO7.D4 4 POINT CONSTRUCTION   N/A 3
MAZDA BT50 EXTRA CAB   ROPSFRO7.E4 4 POINT CONSTRUCTION DIAGONAL SIDE BRACE BARS N/A 3
MAZDA BT50 2007.2011 SINGLE CAB ROPSFRO7.S4 4 POINT CONSTRUCTION   N/A 2.5
MAZDA BT50 2011. ONWARDS DUAL CAB. SIDE CURTAIN AIR BAG COMPATIBLE ROPSFRPXAC-D4 4 POINT CONSTRUCTION   N/A 3.5
MAZDA BT50 2011 – ONWARDS DUAL CAB – HEAVY DUTY- NON SIDE CURTAIN AIR BAG COMPATIBLE ROPSFRPX-D4 4 POINT CONSTRUCTION   N/A 3.5
MAZDA BT50 2011- ONWARDS EXTRA CAB- SUIDE CURTAIN AIR BAG COMPATIBLE ROPSFRPXAC-E4 4 POINT CONSTRUCTION   N/A 3.5
MAZDA BT50 2011- ONWARDS SINGLE CAB – SIDECRTAIN AIR BAG COMPATIBLE ROPSFRPXAC-S4 4 POINT CONSTRUCTION   N/A 3.5

 

 

HOLDEN

HOLDEN RODEO/COLORADO 2008-2012 DUAL CAB  ROPSHCO8-D4 4 POINT CONSTRUCTION   N/A 3
HOLDEN RODEO/COLORADO 2008-2012 EXTRA CAB  ROPSHCO8-E4 4 POINT CONSTRUCTION   N/A 3
HOLDEN COLORADO RG 2012 ONWARDS, DUAL CAB-SIDE AIRBAG COMPATABLE ROPSHCRGAC-D4 4 POINT CONSTRUCTION   N/A 3
HOLDEN COLORADO RG 2012 ONWARDS, DUAL CAB-HEAVY DUTY  ROPSHCRG-D4 4 POINT CONSTRUCTION   N/A 3
HOLDEN COLORADO RG 2012 ONWARDS EXTRA CAB-SIDE AIRBAG COMPATABLE ROPSHCRGAC-E4 4 POINT CONSTRUCTION   N/A 3

 

 

ISUZU

ISUZU D-MAX 2012 ONWARDS DUAL CAB-SIDE AIRBAG COMPATABLE ROPSHCRGAC-D4 4 POINT CONSTRUCTION   N/A 3
ISUZU D-MAX 2012 ONWARDS EXTRA CAB-SIDE AIRBAG COMPATABLE ROPSHCRGAC-E4 4 POINT CONSTRUCTION   N/A 3

 

 

VOLKWAGEN

VW AMAROK 2H 2010 ONWARDS DUAL CAB-SIDE AIRBAG COMPATABLE ROPSVWAM2HAC-D4 4 POINT CONSTRUCTION   N/A 3

 

 

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