Rollover Protective Structures Research Articles

Non-Linear Analysis of a Two Post Roll-Over Protective Structure for Motor Grader

Roll over protective structure (ROPS) is a critical passive safety system of any off-highway equipment. The ROPS is one of the mandatory DGMS requirements and structure is expected to withstand the impact force and maintains the safe space for operator survival during rollover accident. In the present research work, attempts are made to study the non-linear behavior of a two-post roll over protective structure of motor grader having 25T Gross Vehicle Weight (GVW) by using Finite Element Analysis (FEA). In order to enhance the energy absorbing capacity and to have better performance of ROP structure, an interweave energy absorber was introduced inside the ROPS column. CAD model of ROPS was made by using Pro-E modeling software and non-liner analysis was carried by using LS-Dyna software. Non-linear analysis used to compute the maximum deformation and von-misses stress and energy absorption with respect to the lateral, vertical and longitudinal load. Non-linear analysis was carried out for each load case and studied the behavior of ROPS structure. Among all the load conditions, the lateral impact load is a vital role with respect to the energy absorption criteria. The result of non-linear analysis is appreciably par with the standard ISO: 3471(2008) E ROPS performance.

Stakeholder Experiences Implementing a National ROPS Rebate Program: A Grounded Theory Situational Analysis

Currently, little is known about what works, or does not work, in occupational safety implementation efforts. The aim of this study is to (a) explore what works and what does not in scaling up an agricultural safety intervention, and (b) explore these findings in terms of the Consolidated Framework for Implementation Research. A total of 13 stakeholders were interviewed about their experiences with the National Rollover Protective Structures (ROPS) Rebate Program implementation. Nine of these individuals also participated in follow-up interviews one year later. A Grounded Theory Situational Analysis approach was used for data collection and analysis. Two themes emerged from the data. First, the implementation strategy has evolved inconsistently across stakeholders (a barrier to implementation). Second, stakeholder engagement in the implementation is a function of perceived feasibility and “small wins” (an opportunity for improving implementation efforts). Based on the results of this study, two areas of needed improvement to the National ROPS Rebate Program implementation strategy were identified: (a) appropriateness and feasibility of inner setting stakeholder engagement, and (b) receptivity of outer setting stakeholders and potential funders. These findings will be helpful for increasing the success of the implementation, and can also provide guidance to others working on large-scale implementation studies.

The effect of rollover protection systems and trailers on quad bike stability

ABSTRACT Quad bikes are light-weight vehicles which are used for transportation of personnel, equipment, and material in forestry operations such as planning, logging, planting, and fire-fighting. With increased quad bike usage, serious injuries have become an increasing concern. The most common forms of severe incidents occur when a quad bike loses stability, causing injuries as it rolls over the rider trapped beneath. The risk of injuries during a rollover incident can be decreased by equipping the vehicle with rollover protection systems (ROPS), but since ROPS tend to decrease the stability of quad bikes, their use can be a trade-off between the risk of overturning and the outcome of any such incident. In this study, we examine the effects of approach angle, trailer load, ROPS and different hardware configurations on a quad bike’s static stability. We found that approach angle and trailer configurations influenced the vehicle’s stability, although the effect was difficult to quantify in a static environment. Furthermore, the quad bike’s stability was negatively influenced by equipping it with a heavy (44 kg) ROPS. It reduced the static stability by an average of 5.1°, while a light (14.7 kg) prototype ROPS only reduced the vehicle’s static stability by an average of 1.0°. The negative impact a ROPS has on a quad bike’s lateral stability could be effectively counteracted by increasing the quad bike’s track width. Increasing track width by less than 2% (20 mm) compensated for any negative impact that the light prototype ROPS had on the quad bike’s lateral stability.

Effectiveness of Utilizing an Evidence Based Safety Curriculum to Increase Student Knowledge

The purpose of this study was to determine the effectiveness of utilizing an evidence based, “Train the Trainer” approach to increase the safety knowledge and awareness of secondary students. Participating teachers attended a 10-hour, inquiry-based summer training workshop utilizing National Safe Tractor and Machinery Operations Program (NSTMOP) materials focusing on roll-over protection structures, mini-tilt table construction, and on-farm tractor risk assessments. Teachers incorporated workshop lessons into existing curricula. Students completed pretests prior to instruction and posttests after instructional units were delivered. A total of 118 students provided completed preand posttests, with most students identifying as male and more than half enrolled in ninth grade. Wilcoxon Sign-Rank test showed students’ posttests were statistically significantly (Z =-5.22, p < .001) higher than pre-tests. Student performance in this study suggests the Fair Labor Standards Act exemption provided for youth between the ages of 14 and 15 years old who have completed specific safety training needs to be revisited. Additionally, increasing the age restriction for hazardous occupations in agriculture would be consistent with other industries. In order for students to learn agricultural safety in the classroom setting, teachers participating in this study may consider preparation and continuing education programs that incorporate more production-based experiences focused on safety.

Effects of residual stresses and shape deformities on failure of rollover protective structures

Rollover Protective Structures (ROPS) are manufactured typically from components that require forming such as pipe bending process. The manufacturing process creates residual stresses and shape deformities in the pipe structure. These parameters in turn may affect the strength of the pipe to bear the load during rollover. Conventional modeling does not capture the effects of residual stresses and shape irregularities in the pipe resulting from forming. A detailed analysis is therefore required to determine the significance of the manufacturing process on the strength of ROPS. Finite Element Method (FEM) is employed to simulate the bending process. Residual stress and deformation data from bending process analysis are used to further investigate failure of the structure under different loading conditions. The maximum load the structure can withstand, before it loses its stiffness, under a specific displacement is referred to here as failure load. Results revealed that there is a significant difference in the failure loads due to presence of bending process induced residual stresses and due to shape deformities. The model with the residual stresses and shape deformities has higher failure loads as compared to the conventional model. It also has been noted that residual stress is the main contributing factor to this increase in failure load. Parametric study was performed to investigate the effect of pipe wall thickness and radius of the formed bend on the failure loads.

Measurement of Static Lateral Stability Angle and Roll Moment of Inertia for Agricultural Tractors with Attached Implements.

Each year, many fatalities result from rollovers of agricultural tractors in Japan. In addition to rollover protective structures (ROPS) and seat belts, a warning device that alerts the operator of impending rollover based on the tractor stability index is a measure used to prevent rollovers. The stability index requires inertial parameters, which have been measured only for the single body of the tractor, to calculate the warning threshold. In this study, the center of gravity (CoG) and lateral stability angles of three agricultural tractors were measured, and lateral stability angles were also calculated and compared with measured values for three tractor-tiller combinations to analyze the effect of the attached implement on the tractor stability as well as to verify the accuracy of the calculation methods. The roll moment of inertia (RMI) was also measured for two tractors and two rotary tillers, and RMI values for tractor-tiller combinations were calculated. The measurement and calculation results show that the attached implement increased the lateral stability angle of tractors in phase I rollover and decreased the lateral stability angle in phase II rollover, and for a certain tractor-tiller combination, there was no transition from phase I to phase II rollover. The difference between the measured and calculated lateral stability angles in phase I ranged from -3.5° to 2.5°, while that in phase II ranged from 0.2° to 5.2°. The RMI about the longitudinal axis through the CoG was 203 and 433 kg m-2 for tractors A and B, respectively, and 52 and 94 kg m-2 for rotary tillers D and F, respectively. The calculated RMI values were 265 and 540 kg m-2 for tractor-tiller combinations A-D and B-E, respectively.

Characterisation of mechanical energy absorbers developed to complement of roll-over protection structures in agricultural vehicles

Roll-over protection structures (ROPS) and the use of safety belt is a successful combination in agricultural vehicles. If during an accident, a vehicle overturns, a ROPS is designed to deform plastically, absorbing potential energy of the vehicle, while not infringing the safety volume around the driver. The addition of mechanical energy absorbers (MEA) to a ROPS might enhance this behaviour, improving the safety provided. A disc-shaped mechanical energy absorber, designed for this purpose, is analysed and some geometrical and manufacturing features that influence their behaviour are described. Tensile tests of 6 different variants of this absorber have been carried out. The obtained load–displacement curves have been linearized to facilitate the calculation of quantitative parameters that can be used to characterise and compare the behaviour of the tested elements. The relation between some geometrical and manufacturing features of the absorbers and the calculated parameters is discussed. The results show that the proposed mechanical energy absorbers present enough geometrical and manufacturing adjustable variables to cover a wide range of applications.

인장시험과 유한요소해석을 통한 농업용 트랙터 보호구조물용 강재의 물성치 결정을 위한 연구

This study was carried out to standardize the material properties of roll-over protective structure (ROPS) for agricultural tractor. The material properties which were obtained from stress-strain curve, a result of tensile test stress, were used to apply to the virtual test and varied from one production lot to the other and from one manufacturer to the other. And the finite element analysis was performed on the ROPS according to the OECD code. The results show that the load-displacement curves of virtual test were approximately equal to the actual test curves. The manufacturer or lot has been shown to have little effect on the properties of the material. Therefore, it is expected that the representative values that can be used in the finite element analysis can be determined by averaging the property values.

An exploration of rollover protective structures (ROPS) rebate program media coverage: strategies for implementation and sustainment

BackgroundMedia advocacy plays an important role in public health initiatives, as it can provide vital information to target populations, policy makers, or other relevant stakeholders. Unfortunately, little is currently known about the use of media advocacy to promote occupational safety and health programs. This study explores media coverage related to the Rollover Protection Structure (ROPS) Rebate Programs, which were designed to encourage the use of rollover protection on agricultural tractors, thus reducing the risk of tractor overturn fatalities. The Program’s portrayal in the media, as well as the role that the media has played in implementing and sustaining these Programs.MethodsMedia articles pertaining to any of the state-based or National ROPS Rebate Programs and published between November 1, 2006 and October 31, 2018 were included for review. Discourse analysis was used to understand the messages portrayed by the media and how those messages shaped the outcomes of the ROPS Rebate Programs.ResultsDuring the study period, 212 unique articles were published about the ROPS Rebate Programs. While these articles all portrayed the ROPS Rebate Programs in a largely positive light, they were used at different stages, from pre-implementation through sustainment of the ROPS Rebate Programs, and to different extents.ConclusionsMedia articles have played an important role in implementing and sustaining the ROPS Rebate Programs. Based on the results of this study, more robust and continuous media coverage are important for the longevity and success of public health programs.

Method of increasing the efficiency of forest machine roll-over protective structure

Current standards in the field of self-propelled machinery for forestry require equipping tractor cabins with roll-over protective structures (ROPS). It is necessary to reduce the risk of operator’s injuries caused by tractor rollovers or falling trees. This article deals with the way of increasing the energy absorption capacity of forest machine cabin roll-over protective structure. The ability to absorb certain amount of potential energy during deformation is the one of basic requirements to cabin of a forest machine. The risk of injures to the operator is reduced by using energy-absorbing cab support in the construction of roll-over protective structure. The protective effect is attained by plastic strain of cab support elements, that provides operator’s protection during an accidental roll-over. The article presents the design of the cab support, describes its functional principle in the event of an emergency

Key factors for successful implementation of the National Rollover Protection Structure Rebate Program: A correlation analysis using the consolidated framework for implementation research.

Objectives On US farms, tractor overturns are the leading cause of death; however, these fatalities are preventable with the use of a rollover protection structure (ROPS). A ROPS rebate program was established in New York in 2006 to address these fatalities. Due to its success, the program expanded to six additional states before being implemented as the National ROPS Rebate Program (NRRP) in 2017. The aim of this study was to evaluate the success of the NRRP implementation using short- and long-term ROPS outcome measures and identify which components of the consolidated framework for implementation research (CFIR) correlate with these outcomes. Methods Stakeholders involved in the NRRP implementation were surveyed at four time points, beginning at the time of the NRRP launch and then every six months. These surveys measured 14 relevant CFIR constructs. Correlations between CFIR survey items (representing constructs) and three outcome measures (intakes, funding progress, and retrofits) were used to identify CFIR survey items that are predictive of the outcomes. Results Eight CFIR survey items were highly correlated (rho ≥0.50) with at least one of the three outcome measures. These eight CFIR survey items included four constructs: access to knowledge and information, leadership engagement, engaging (in fundraising and funding requests), and reflecting and evaluating. Conclusions The results of this study provide important guidance for continuing the implementation of the NRRP. Similarly, these findings can inform the evaluation of other similarly structured implementation efforts and the application of CFIR in a variety of settings.

Models to predict the force to operate front foldable rollover protective structures for narrow-track tractors

Narrow-track tractors are specifically designed to operate in narrow clearance areas, such as orchards and vineyards. A specific rollover protective structure (ROPS) was developed with a reduced clearance zone. Front mounted on the tractor it was designed to be lowered, if strictly required, to perform normal operations. However, this feature of the ROPS has been incorrectly used and this can be responsible for fatal injuries to the driver. The actuation force for raising and lowering the foldable ROPS is a function of design parameters, such as the mass, dimensions and hinge connection between the free upper and the fixed lower part of the structure. Nevertheless the accessible tractor zones and ROPS grasping area influence the operator's position in manual handling and affect the actuation force to be sustained during operation. Three theoretical models were developed to predict the actuation force using as reference ROPS shape, ROPS main dimensions and material density. The proposed models could help tractor and ROPS manufacturers to calculate the force required for operating the ROPS, planning the need for assisting devices when manual handling ROPS. Six new narrow-track tractors mounted with front foldable ROPS were evaluated in terms of their dimensions and the ROPS accessible zones for the operator. Results showed that the actuation force became higher, increasing the mass and dimensions of the tractors, not only because of the heavier ROPS but also for the uncomfortable zone during ROPS actuation. Near the articulation hinge of the ROPS the actuation torque is characterised by a higher force.

Tractor Rollover Protection: Is the Incorrect Use of Foldable Rollover Protective Structures Due to Human or to Technical Issues?

To identify the critical behaviors that may hinder the correct use of foldable rollover protective structures (FROPS) on tractors and to explore the influence of user factors and FROPS technical characteristics. FROPS are effective in preventing fatal injuries in rollover accidents if they are in the upright position. However, many farmers leave FROPS folded down. Twenty farmers and sixteen models of tractors were involved in the study. Operators were observed while raising the FROPS, and the observed behaviors were correlated with user factors and FROPS technical features. In the initial rotation of the FROPS, higher lowered roll-bar to ground distance and FROPS pivot-pin to ground distance required more awkward and unbalanced postures (p = .02 and p = .01, respectively). When rotating the FROPS in upright position, smaller stature of the participants and higher FROPS pivot-pin to ground distance were significantly correlated with using the tractor's rear 3-point lower links as a supporting surface (p = .01 and p = .02, respectively). FROPS might be revised considering users' comfort in use and anthropometric variability, to improve reachability, avoid risky behaviors, and enhance FROPS operation. Technical solutions to enhance FROPS accessibility may be developed, particularly by providing safe surfaces to support operators and highlighting the grasping points. Further best practices and information on correct gestures to handle the FROPS should be included in the tractor manual.

Operator protection in rollover events of articulated narrow track tractors

Articulated steering arrangements, wheeled or tracked, are commonly used on agricultural tractors and earth moving machines. In Continental Europe and Italy in particular, this configuration is typical of narrow track tractors. Despite their widespread use, there is little research that specifically investigates articulated tractor rollover protective structure (ROPS) in-field performance with respect to the ROPS test procedures. The aim was to investigate the relevance of the standardised ROPS test procedures regarding articulation joint mobility. The shortcomings of the procedures concerning the Clearance Zone and ROPS testing are evidenced and discussed. It is a recommendation of this work that an update of the international testing procedure be developed for articulated tractor types. The paper indicates how this may be accomplished and presents remedial measures that can be implemented in the interim until this latter goal is achieved.

Falling-object protective structure for tractors in service: Prototype design and validation

A falling-object protective structure (FOPS) is a safety device fitted to self-propelled agricultural vehicle that provides reasonable protection for the operator in the driving position against accidental falling objects. To be certified, a FOPS undergoes a standardised full-scale destructive test to prove its resistance to falling objects. This destructive test procedure is expensive and unsuitable for custom-made FOPS manufactured individually. In the case of a tractor in service, for which manufacturers do not offer a FOPS device, there is no certified method to evaluate the performance of a custom-designed FOPS, other than this destructive procedure. The work described in this paper, funded by the French Agriculture Ministry, proposes a design and a validation of a cantilever FOPS to equip tractors that have two-post rear roll-over protective structures (ROPS). The main requirement of the custom-designed FOPS is to meet the performance and protection level of certified structures. A design approach with the goal of achieving optimal design was adopted. At each stage, design alternatives are compared qualitatively and quantitatively, using numerical simulation, to assist decision making. A validation method based on mathematical modelling and full-scale tests, according to standardised test conditions, was adopted. This validation process made it possible to approve the design choices and to determine the scope of validity of the proposed FOPS.

Foldable rollover protective structures: Universal lift-assist design

The numbers of agricultural tractor rollover fatalities occurring with foldable rollover protective structures (FROPS) in their lowered position are significant. Raising and lowering the FROPS is a time consuming and strenuous process, and operators often leave the FROPS in the folded-down position providing no protection during a rollover. The purpose of this project is to design, manufacture, and test a lift-assist mechanism to raise and lower the FROPS from the operator's seat. The lift-assist design is based on the FROPS actuation forces, FROPS and tractor dimensions, and ergonomics engineering standards [SAE J898/ISO 6682 and SAE J1814]. The design considered can be retrofitted and will not modify or compromise the FROPS structure. A universal lift-assist lever design has been constructed and successfully tested for three FROPS of different sizes meeting appropriate ergonomics engineering standards. The operator actuation forces were less than the 75 N allowable maximum, and within the zones of comfort and reach for the operator. The lift-assist design uses an energy absorbing torsional spring to accommodate heavier FROPS designs.

Development of an inexpensive rollover energy dissipation device to improve safety provided by ROPS

Tractor overturn is the most common cause fatal accidents in agriculture. Installing rollover protective structures (ROPS), in combination with the use of a safety seat belt, is the best way to avoid fatalities. A ROPS must be able to absorb the rollover energy without collapsing or suffering such a deformation that infringes the safety zone, where the tractor operator must remain. Therefore, any device able to absorb rollover energy, prevent ROPS collapse or infringement of the safety zone, increases the safety provided. An energy dissipation device was developed and tested. It contained a metal piece placed in each one of the four anchoring points to attach the ROPS to the tractor frame such that the piece began to deform and dissipate energy when the ROPS reached a deformation that could compromise the safety of the driver. At deformation the piece raised the closest anchoring point of the ROPS, forcing the ROPS to pivot around the opposite anchor point while it absorbed large amounts of energy, preventing the ROPS approaching the safety zone. The device designed and constructed specifically to be mounted on a Daedong D85 tractor model and has been tested to calculate the safety increase provided by its installation. The results demonstrated that the developed device, costing less than € 20, increased the safety margin by more than 50%.

Comparing the influence of Roll-Over Protective Structure type on tractor lateral stability

Tractor overturns are a major cause of death in agriculture. Many variables are involved. The Roll-Over Protective Structure (ROPS) has been invented to minimise the risks of driver injuries in a tractor overturn. Narrow-track tractors for orchard and vineyard operations are mainly available with two different ROPS types: an enclosed cab frequently fitted with filters and air-conditioning system or a simple two post ROPS designed to be folded down to allow the tractor to operate in a reduced surrounding space. Concerning stability, the tractor lateral stability angle is the result of the tractor configuration and its position with respect to the ground slope. The aim of the paper was to study the effect of ROPS type on tractor stability performance. The tractor stability parameters were evaluated on 22 modern narrow-track tractors measuring mass, track-width, wheelbase, Centre of Gravity (CoG) and Moments of Inertia (MoI). The evaluation considered pairs of tractors equipped with two post ROPS and cab ROPS. In the design of compact narrow-track tractors the cab fitment keeps the wheelbase and track-width of the tractor unchanged with respect to the front foldable ROPS but affects the mass, position of the CoG and longitudinal and transversal MoI. Data show an increase in tractor mass and higher CoG and MoI for the cab fitment with respect to the two post ROPS. A recent international debate on the safety performance of two post ROPS was consequent to the incorrect use of the foldable ROPS in field operations. Cab ROPS is thus often claimed to provide higher protection to the driver. This investigation denotes that on sloping fields narrow-track tractors fitted with a cab ROPS reach the lateral unstable state at a lower angle than two post ROPS tractors; consequently, the stability performance of the tractor worsens.

Stereovision system for estimating tractors and agricultural machines transit area under orchards canopy

Managing orchards requires delicate agricultural operations being typically carried out in narrow zones where the operators usually drive machineries under stress that could result in poor performance. In such conditions, the use of technology would help manage the machines to reduce the hazardous work and eventual damage to the plants. To safely drive a tractor, the driver needs to be aware of its surroundings, thus a stereovision system can provide helpful information. Stereo imaging has proven to be an effective three-dimensional vision system. Indeed, the range (or third coordinate) information is useful to detect the obstacle distances. Such distances, when detected during agricultural operations, could be used to assist the operator in driving the tractor at regular or variable working speeds and eventually to provide manufacturers useful indications to model the form of ROPS (roll over protection structure). This study aimed to verify the closeness of agreement between manual and stereo-image measurements, and thus to provide helpful information regarding safety and working purposes. The system used a custom low-cost dual web-camera in combination with an image analysis algorithm in order to automatically extract the information needed. Manual independent measurements were carried out using a metric tape (sensitivity 1 cm). A regular structure was used for the analysis: four rows of ten trees each one. Alternated red and blue paper markers were placed on the hazelnut trees (two per tree) of two couples of rows for enhanced visibility. For each couple of trees (one on the right, the other on the left), the four markers formed a trapezoid that was measured. The results of the analysis demonstrated that the stereo vision provided distance measurements with reasonable accuracy (error <5%) in the range of distances lower than 20 m. The resolution assessed for the developed video system is suitable for obtaining distance information in real scenes. This information could be used to assist drivers to operate agricultural machineries through narrow tree rows during work execution. Moreover, such information could be used for safeguarding decision-making and/or for controlling some tractor functions such as continuing moving, changing driving direction, changing 3-point hitch position, reducing transmission speed, halting the tractor. These functions will be necessary before tractors become fully autonomous. Finally, the measured distances, marking the narrow transitions between the tree rows, could be also used to study the ROPS form, both for working safely and for avoiding possible damage caused to the hazel trees laterally. Keywords: stereovision, precision agriculture, digital agriculture, hazelnut; canopy, ROPS, orchards DOI: 10.25165/j.ijabe.20191201.4123 Citation: Costa C, Febbi P, Pallottino F, Cecchini M, Figorilli S, Antonucci F, et al. Stereovision system for estimating tractors and agricultural machines transit area under orchards canopy. Int J Agric & Biol Eng, 2019; 12(1): 1–5.

Barriers and Motivators for Tractor ROPS Retrofitting in Iowa.

Iowa State University Extension and Outreach conducted an assessment of Iowa farm operators' perceptions of the barriers and motivators when considering retrofitting tractors with rollover protective structures (ROPS). A statewide sample of approximately 2,000 farm operators was surveyed in the 2017 Iowa Farm and Rural Life Poll. A series of questions was asked to evaluate the importance of potential barriers to decisions to not retrofit a tractor and potential motivators that could influence the decision to retrofit or purchase a tractor with ROPS. The survey received a 48% response rate (999 responses). Among the 76% of Iowa farm operators who reported at least one pre-1985 tractor, only 18.6% reported that all of those tractors had ROPS. The remaining 81.4% had at least one tractor that did not have ROPS. Iowa farm operators' perceptions of the barriers and motivators when considering retrofitting tractors with ROPS are shared. The results of Iowa farm operators' perceptions will be used as Iowa State University Extension and Outreach prepares to align efforts with the National Tractor Safety Coalition and participate in the National ROPS Rebate Program, with the goal of reducing tractor fatalities.