Mobile Machinery Research Articles

A digital twin framework to support vehicle interaction risk management in the mining industry

In recent years, transport-related accidents, notably those involving trackless mobile machinery (TMM), have consistently ranked among the top three causes of fatalities and injuries in the South African mining industry (SAMI) [1]. These accidents arise from a combination of mechanical and technical malfunctions, environmental factors, and human or machine operator errors. Remarkably, these incidents persist despite the existence of specific regulations, standards, and codes of practice for transportation and machinery. This paper introduces a digital twin framework for TMM, which employs a systems engineering approach combined with software tools and computational analysis. This framework aims to enhance the current regulations by offering a continuous, quantitative risk assessment. By modelling and detecting non-conformance and adverse vehicle interaction events, the framework provides a quantitative risk analysis that complements the prevailing qualitative methods reliant on historical data and operational experience. A case study conducted at the CSIR main campus in Pretoria showcases the potential of the TMM Digital Twin.

Technologies for retrofitting non-road mobile machinery to reduce diesel emissions: a review and recommendation

Non-road mobile machinery (NRMM) in Hong Kong emits considerable emissions and has been a major contributor of environmental regression and harm to the health of citizens. The severe problem caused by considerable NRMM diesel emissions has drawn the attention of the Hong Kong Government. However, the existing measures for reducing NRMM emission mainly target new NRMM while old in-service ones are being left largely unregulated. After a long time of use, in-service NRMM becomes inefficient through deterioration, which results in higher levels of diesel emissions, which are extremely harmful to public health. Transforming in-use dirty NRMM which are exempted from regulations on being greener and more fuel-efficient is an extremely urgent direction for the Hong Kong Government to pursue. Retrofitting in-service high-emitting NRMM can remarkably reduce emissions by using emission reduction technologies, improve the air quality, and achieve notable health benefits for people living or working in or near construction sites. Technologies for reducing emissions from NRMM are crucial for making NRMM greener and cleaner. Thus, this study reviews the technologies widely used for retrofitting NRMM to reduce emissions, to provide some significant insights and recommendations in the case of Hong Kong for initiating retrofit programmes and promote the application of emission reduction technologies.

Two Cooling Approaches of an Electrohydraulic Energy Converter For Non-Road Mobile Machinery

The energy efficiency of non-road mobile machinery can be improved by using e.g., an electric drive system as a servo controller of a hydraulic machine to get an efficient electro-hydraulic (EH) converter. However, the cooling of EH devices require more understanding and new innovations. This work presents a design of a 7-kW integrated EH machine and studies its electric motor heat transfer phenomena both experimentally and numerically. Further, to better match the torque and speed performances of the permanent magnet synchronous motor (PMSM) and the hydraulic machine a planetary step-down gear is utilized to triple the output torque of the PMSM. The integrated motor and gear system is then connected to a bent axis piston hydraulic machine, which is capable of operating both as a motor and a pump. Two different electric motor cooling approaches are investigated. The first cooling approach is to use some hydraulic oil inside the motor-gear chamber to let it flow freely as a result of the rotor rotation and move the losses to the surface of the converter cover, which is equipped with some air cooling fins. In the second approach, the oil flows through the converter and removes the losses more effectively. Motor losses and thermal behaviour are studied within these two cooling approaches. Computational fluid dynamic (CFD) simulations are performed to find how the coolant is distributed inside the machine and how heat is distributed in the device.

Tampering of environmental protection systems on vehicles: Status quo and perspectives

Pollutant emissions of road vehicles have significantly reduced thanks to the environmental protection systems (EPS), but tampering with these systems can lead to very low efficiency. In the DIAS project, it was found that there is a substantial market for both light- and heavy-duty vehicles and non-road mobile machinery. The main motives are reduction of costs for repair, consumables and downtime, performance tuning, and increase of the exhaust sound level. Tests with several tampering devices revealed that tampering could deactivate or enable the removal of the EPS, and prevent necessary repair of components without malfunction indication and driver inducement occurring, although several tampering devices and services were not successful. Finally, the testing program enabled the definition of the necessary countermeasures to detect and prevent tampering with these systems.

Time Series Forecasting Fusion Network Model Based on Prophet and營mproved LSTM

Time series forecasting and analysis are widely used in many fields and application scenarios. Time series historical data reflects the change pattern and trend, which can serve the application and decision in each application scenario to a certain extent. In this paper, we select the time series prediction problem in the atmospheric environment scenario to start the application research. In terms of data support, we obtain the data of nearly 3500 vehicles in some cities in China from Runwoda Research Institute, focusing on the major pollutant emission data of non-road mobile machinery and high emission vehicles in Beijing and Bozhou, Anhui Province to build the dataset and conduct the time series prediction analysis experiments on them. This paper proposes a P-gLSTNet model, and uses Autoregressive Integrated Moving Average model (ARIMA), long and short-term memory (LSTM), and Prophet to predict and compare the emissions in the future period. The experiments are validated on four public data sets and one self-collected data set, and the mean absolute error (MAE), root mean square error (RMSE), and mean absolute percentage error (MAPE) are selected as the evaluation metrics. The experimental results show that the proposed P-gLSTNet fusion model predicts less error, outperforms the backbone method, and is more suitable for the prediction of time-series data in this scenario.

Validating Measurement Structure of Checklist for Evaluating Ergonomics Risks in Heavy Mobile Machinery Cabs

Heavy mobile machinery cabs and their equipment are still not well adjusted to operators, so it is not surprising that we are still witnessing huge consequences of accidents at sites where they operate. The checklist with 39 questions, based on the previous research, is formed, and its’ measurement structure has been tested on the sample of 102 transport, construction, and mining machines, including cranes, excavators, bucket wheel excavators, bulldozers, loaders, graders, backhoe loaders, trenchers, dump trucks, and scrapers by correlation analysis, Cronbach’s alpha, Spearman-Brown and Kendall’s W coefficient, exploratory factor analysis, and confirmatory factor analysis. The results validate the measurement structure of a checklist with only 17 items and five constructs. The results show that special attention should be put to the design of armrests and working conditions/exhaust gases, which are negatively correlated to cab interior space and task visibility. All other correlations between seat characteristics, the characteristics of armrests, whole-body vibration influences, reaching commands, the characteristics of cab interior space and environments, and interpersonal relationships are positive, which means that improvements to one area lead to improvements in another. Accordingly, the proposed model should be used for the fast, efficient, and cost-effective evaluation of ergonomics risks and as a guideline for further cab design improvements.

Optimization of U-shaped flow channel by RBFNN and NSGA-II

Mobile machinery is in desperate need of weight reduction. To achieve this goal, their hydraulic reservoirs are developing in the direction of miniaturization and lightweight. However, this development of the hydraulic reservoir can lead to excessive air content in the hydraulic system and hard pump suction. At present, how to solve this conflict has not been studied and how the hydraulic reservoir structure influences the deaeration and inside pressure drop is not clear. In this paper, a U-shaped flow channel in a minimized hydraulic reservoir was numerically optimized and analysed for efficient deaeration of hydraulic systems and minimal inside pressure drop. Based on the multiphase flow simulation database, radial basis function neural networks and an NSGA-II were combined for the flow channel optimization. Results showed that two optimized structures raised the degassing rate by 8.8% and 18.1% and reduced the pressure drop rate by 23.7% and 13.5%, respectively. The flow field analysis and bubble motions were investigated among the initial and optimized flow channel structures. On the baffle's left side, bubbles were degassed by the buoyance force. On the baffle's right side, the wall confinement bubbly jet transformed bubbles to the free surface and degassed, but this jet formed by the deep baffle would increase the pressure drop, which agrees with the parameter sensitivity result. Additionally, vortex structures caused by the jet flow entrained bubbles and impeded deaeration. Consequently, the strong vortex was suppressed in optimum models to increase degassing capacity.

Immediate Vehicle Movement Estimation and 3D Reconstruction for Mono Cameras by Utilizing Epipolar Geometry and Direction Prior

Motion estimation of surrounding objects is indispensable to any mobile machinery. The paper proposes a method to solve the estimation and reconstruction problem of dynamic objects with a mono camera. Using the relative camera motion and detected rigidly moving objects on the image, we estimate their movement up to a scale factor. Utilization priors about their moving direction are used to estimate the transformation, which maps the 3D object from the previous frame to the actual one. Our two-frame method works twice the speed or more as other methods using three frames or more for the estimation, and we do this without any constraints. We evaluate our method on various traffic scenarios of different autonomous driving datasets.

Study on the control targets and measures for total diesel consumption from mobile sources in Beijing, China

Based on the current air pollution control and CO2 emission reduction policies, this study analyzed the energy structure, number of motor vehicles and nonroad mobile machinery, energy consumption and pollutant emissions in Beijing. Furthermore, the diesel consumption characteristics and challenges for emission reduction in key fields were investigated, such as medium- and heavy-duty diesel trucks, long-distance passenger and tourist diesel vehicles, and nonroad machinery, which are areas with difficult-to-reduce diesel consumption. Control targets and measures for total diesel consumption were also proposed. The results indicated that the higher diesel consumption per unit area in Beijing is related to the larger passenger car and freight truck populations. In recent decades, the number of diesel vehicles has increased, the vehicle type structure has been optimized, the proportion of vehicles with high emission standards has increased, and the absolute pollutant emissions have decreased. Among these, nitrogen oxides (NOx), fine particulate matter (PM2.5) and volatile organic compound (VOC) emissions of different models decreased by 39.5%, 75.3% and 42.8%, respectively, while carbon dioxide (CO2) emissions from diesel combustion decreased by 32%. Moreover, medium and large passenger vehicles, medium- and heavy-duty trucks and construction machinery are the main contributors to diesel consumption. These vehicle types are also difficult to control and reduce, and their replacement by new-energy vehicles is relatively limited. The main control measures for diesel consumption are as follows. First, a green transportation mode can be adopted for goods that can be converted from roads to railways. Second, fuel consumption reduction for nonroad mobile machinery can be realized by tightening fuel consumption limits, setting appropriate maximum retirement life, establishing low- or ultralow-emission zones, and establishing demonstration plots for electric vehicle (EV) substitution for mobile machinery. To improve the air quality and take the lead in carbon neutrality in the future, Beijing must further accelerate the energy structure adjustment and the development of new-energy vehicles in the transportation sector. Carbon neutralization is an important opportunity for diesel consumption reduction, and the synergistic control of atmospheric pollution and carbon emissions from diesel combustion must be strengthened.

Non-Road Mobile Machinery Emissions and Regulations: A Review

Non-Road Mobile Machinery (NRMM) incorporate a wide range of machinery, with or without bodywork and wheels, and are installed with a combustion engine and not intended for carrying passengers or goods on the road. These are used in many different sectors including construction, agriculture, forestry, mining, local authorities, airport and port ground operations, railways, inland waterways and within the household and gardening sector. This article presents a review of the state of knowledge with regard to non-road mobile machinery, particularly focusing on their regulation and the atmospheric emissions associated with them. This was undertaken as there is currently a lack of this information available in the literature, which is an oversight due to the potential for Non-Road Mobile Machinery to form a greater part of atmospheric emissions in the future, as other areas of emissions are tackled by regulations, as is outlined in the article. Emissions such as particulate matter (PM), carbon oxide (CO), carbon dioxide (CO2), hydrocarbons (HC), nitrogen oxides (NOx) and sulphur oxides (SOx) from NRMM contribute considerably to total emissions released into the air. NRMM are diverse in application, engine type and fuel use, and are therefore difficult to categorise. This leads to numerous issues when it comes to the control and regulation of their emissions. The most recent European and international regulations are outlined in this article. Due to the divergent nature of NRMM, their emissions profiles are highly varied, and in-use emissions monitoring is challenging. This has led to a lack of data and inaccuracies in the estimation of total emissions and emission inventories. It was assumed in the past that emissions from non-road sources did not contribute as significantly to total emissions as those from on-road sources. This assumption was partly due to the difficulty in gathering relevant data, and it was disproven in the 1990s by studies in The Netherlands, Finland and Sweden. It is now understood that NRMM will eventually surpass on-road vehicles as the leading source of mobile pollution due to the continuing efforts to reduce emissions from other sources. Many states worldwide gather emissions data from NRMM, and EU member states are required to report their emissions. As of January 2017, a new European regulation establishing limits for gaseous and particulate pollutants from NRMM applies, and this regulation also defines administrative and technical requirements for EU approval. The exact number of NRMM and the total amount of fuel they use is currently not known. In Ireland, for example, their fuel use has been reported under stationary boilers and engines. However, this results in the underestimation of emissions of some pollutants (NOx in particular) because emissions of air pollutants tend to be higher in mobile than in stationary machinery.

Numerical Investigation of a Fuel Cell-Powered Agricultural Tractor

In recent years, growing awareness about environmental issues is pushing humankind to explore innovative technologies to reduce the anthropogenic sources of pollutants. Among these sources, internal combustion engines in non-road mobile machinery (NRMM), such as agricultural tractors, are one of the most important. The aim of this work is to explore the possibility of replacing the conventional diesel engine with an electric powertrain powered by a hybrid storage system, consisting of a small battery pack and a fuel-cell system. The battery pack (BP) is necessary to help the fuel cell manage sudden peaks in power demands. Numerical models of the conventional powertrain and a fuel-cell tractor were carried out. To compare the two powertrains, work cycles derived from data collected during real operative conditions were exploited and simulated. For the fuel-cell tractor, a control strategy to split the electric power between the battery pack and the fuel cell was explored. The powertrains were compared in terms of greenhouse gas emissions (GHG) according to well-to-wheel (WTW) equivalent CO2 emission factors available in the literature. Considering the actual state-of-the-art hydrogen production methods, the simulation results showed that the fuel-cell/battery powertrain was able to accomplish the tasks with a reduction of about 50% of the equivalent CO2 emissions compared to traditional diesel-powered vehicles.

Integrated Harvesting of Medium Rotation Hybrid Poplar Plantations: Systems Compared

In this study, the authors provide a direct comparison made between whole tree-harvesting (WTH) and cut-to length (CTL) methods, which was conducted in two sites in the Slovak Republic and applied to poplar plantations. Both systems, WTH and CTL, have been employed at the highest mechanization level in two sites: “Nivky” and “Skalica”. Two different strategies, namely, “mass handling” and “small-scale mechanization”, have been used for WTH and CTL, respectively. The study results showed that the level of productivity (ODT SMH−1) in the felling operation was almost double for WTH than for the CTL method in Nivky (+84%) and more than double in Skalica (+113%). The extraction operation under WTH showed a productivity increase from one fifth (+20%) to more than double (104%) that of the CTL method in the Nivky and Skalica sites, respectively. Regarding cost-efficiency (EUR ODT−1), the WTH system offers a similar trend except with respect to extraction in Nivky (higher productivity site), in which the CTL extraction was 4.5% less expensive than the WTH extraction. The study results show that the mass-handling technique deployed in the WTH system offers very good performance in poorer plantations since the very small tree size and low-growing stock challenge the CTL system more than the WTH system. The total operation (felling, bucking, and extraction) costs (EUR ODT−1) recorded by the study in commercial conditions (as contractors perform for revenue purposes) were 32.50 and 45.80 EUR ODT−1 for CTL and 43.30 and 53.60 EUR ODT−1 for WTH for the higher-yield site (Nivky) and lower-yield site (Skalica), respectively. Regarding the WTH System, the researchers found that the drop in efficiency (and the consequent rise in the costs-per-ton of product) depends largely on the bucking phase conducted using the harvester at the landing of the stacked piles of interlocked trees. The main results of this study demonstrate the promising strategy of mass handling associated with the WTH system in medium rotation coppice (MRC) harvesting and shows that bucking is the weaker phase. Future efforts must be made to ensure feasibility of the “mass handling” strategy alongside the entire workflow by means of finding suitable mobile machinery that can delimb, debark, and crosscut tree bunches instead of single trees.

Differently shaped Al2O3-based Pd catalysts loaded catalytic converter for novel non-road mobile machinery exhaust systems

Differently shaped Al2O3-based Pd catalysts loaded catalytic converter for novel non-road mobile machinery exhaust systems

Characterization of air pollutant emissions from construction machinery in Beijing and evaluation of the effectiveness of control measures based on information code registration data.

Non-road mobile machinery (NRMM), mainly construction machinery, has a high emission intensity of air pollutants, significantly impacting urban air quality. Most previous estimates of NRMM emissions have employed a top-down approach mainly based on estimates of energy consumption, leading to large uncertainties. This study uses the information code registration data specified in the latest regulations to establish a bottom-up method for emission accounting to more precisely identify the characteristics of air pollutant emissions from construction machinery in Beijing in 2020. Moreover, the study evaluates the effectiveness of the implementation of the corresponding control measures in conjunction with the current situation of pollution control of NRMM in Beijing. The results show the following: (1) Based on the information code registration data, there are 37,000-based fuel construction machines, with excavators accounting for the largest proportion (56%), loaders and forklifts also accounting for large proportions (19% and 15%, respectively), representing the main types of construction machinery. (2) Information code registration data better reflect the actual situation of construction machinery emissions than the top-down method; the emissions of the main air pollutants NOx, PM2.5, and VOCs amount to 12,000 tons, 600 tons, and 1000 tons, respectively, which are overestimated to some extent by the top-down method. (3) Loaders and excavators have a large contribution to emissions, accounting for 80-91% of these three pollutants emissions; there is a large quantity of machinery classified into the China III standard, accounting for 64-68% of these pollutants emissions; the designation of low emission zones banning the use of high-emission machinery plays a positive role in pollution reduction, but high-emission machinery is still used in these regions, which requires further attention. (4) In the future, the scope of these regions banning high-emission machinery and the types of controlled machinery should be further expanded, and the supervision and enforcement should be strengthened, Furthermore, the structural adjustment and energy conservation of construction machinery should be promoted, and measures such as electrification should be implemented for part of the light construction machinery to continue to reduce pollutant emissions.

A Study on Additive Manufacturing for Electromobility

Additive manufacturing (AM) offers the possibility to produce components in a resource-efficient and environmentally friendly way. AM can also be used to optimise the design of components in mechanical and physical terms. In this way, functionally integrated, lightweight, highly efficient, and innovative components can be manufactured with the help of additive manufacturing in terms of Industry 4.0. Furthermore, requirements in the automotive industry for drivetrain components are increasingly being trimmed in the direction of efficiency and environmental protection. Especially in electromobility, the topic of green efficiency is an essential component. Exhaust emission legislation and driving profiles for evaluating vehicles are becoming increasingly detailed. This offers the potential to apply the advantages of AM to vehicle types such as conventional, utility vehicles, and nonroad mobile machinery (NRMM), independent of the electrical drivetrain technology (hybrid or fully electrical). AM also allows for us to produce optimally adapted components to the respective requirements and use cases. In this review, the intersections of AM and electromobility are illuminated, showing which solutions and visions are already available for the different vehicle types on the market and which solutions are being scientifically researched. Furthermore, the potential and existing deficit of AM in the field of electromobility are shown. Lastly, new and innovative solutions are presented and classified according to their advantages and disadvantages.

Study on Emission Characteristics and Emission Reduction Effect for Construction Machinery under Actual Operating Conditions Using a Portable Emission Measurement System (Pems).

With the acceleration of urban construction, the pollutant emission of non-road mobile machinery such as construction machinery is becoming more and more prominent. In this paper, a portable emissions measurement system (PEMS) tested the emissions of eight different types of construction machinery under actual operating conditions and was used for idling, walking, and working under the different emission reduction techniques. The results showed that the pollutant emission of construction machinery is affected by the pollutant contribution of working conditions. According to different emission reduction techniques, the diesel oxidation catalyst (DOC) can reduce carbon monoxide (CO) by 41.6–94.8% and hydrocarbon (HC) by 92.7–95.1%, catalytic diesel particulate filter (CDPF) can reduce particulate matter (PM) by 87.1–99.5%, and selective catalytic reduction (SCR) using urea as a reducing agent can reduce nitrogen oxides (NOx) by 60.3% to 80.5%. Copper-based SCR is better than vanadium-based SCR in NOx reduction. In addition, the study found that when the enhanced 3DOC + CDPF emission reduction technique is used on forklifts, DOC has a “low-temperature saturation effect”, which will reduce the emission reduction effect of CO and THC. The use of Burner + DOC + CDPF emission reduction techniques and fuel injection heating process will increase CO’s emission factors by 3.2–3.5 and 4.4–6.7 times compared with the actual operating conditions.

Investigation of real operation gaseous emissions from a diesel locomotive

• The high BSFC at the idle operation decreases as the BMEP increases. • Highest BTE at the mid-BMEP, corresponding to 50% load condition. • Total amount of gaseous emissions increases as the BMEP increases. • Lowest brake specific gaseous emissions at the mid-BMEP. • Test mode including high emission-measured condition provides with low uncertainty. Many investigations on the fuel consumption and the emission characteristics of diesel engines for non-road mobile machinery (NRMM) have been carried out in the various conditions of steady-state and transient operation, and the knowledge obtained from these studies provides substantial information to analyze real operation emissions. Detailed information on the fuel efficiency and the emission under the real operation condition, however, is still needed to provide significant information to develop the advanced after-treatment system as well as to analyse the fuel efficiency and emissions from the NRMM operating real-world conditions. This study aims to investigate the fuel efficiency and the gaseous emissions from a diesel locomotive. The experiment was carried out with a Portable Emissions Measurement System (PEMS), and studies the fuel efficiency, the overall gaseous emissions, the association of gaseous emissions and brake mean effective pressure (BMEP), and the load conditions for the emission measurement.

Research on Mobile Machinery NOx Emission Control Based on a Physical Model and Closed-Loop Control

Mobile machinery means a power-driven vehicle that is specifically designed and constructed to perform work on or off the road. To reduce the nitrogen oxide (NOx) emissions that come from mobile machinery, a combination of a physical model and closed-loop control is applied to the selective catalytic reduction (SCR) system. Based on the design of the variable cross-section extended exhaust structure, the differential pressure measurement was achieved, and the physical model of the exhaust flow based on the differential pressure was established. Based on the analysis of the heat and mass transfer process of the SCR catalyst, a prediction model for the internal temperature field of the catalyst was established by combining the upstream and downstream exhaust temperature sensors. Using the SCR downstream nitrogen oxides signal and the proportional–integral–derivative (PID) closed-loop control algorithm, segmented PID closed-loop control under the large hysteresis response of the SCR system was realized. The above algorithms were used to form the control code through MATLAB/Simulink and downloaded to the embedded microprocessor. The test results show that the established model can realize the real-time calculation of the exhaust gas flow rate and the internal temperature of the catalyst. Under steady-state conditions, the calculation error of the exhaust flow rate is less than ±3%, and the calculation error of the catalyst temperature is less than ±5%. Under transient conditions, the calculation error of the exhaust flow rate is less than ±9%, and the calculation error of the catalyst temperature is less than ±8%. The nitrogen–oxygen signal-based PID closed-loop algorithm can improve the nitrogen–oxygen conversion efficiency and control accuracy of the model.

Effect of Tampering on On-Road and Off-Road Diesel Vehicle Emissions

Illegal manipulation (i.e., tampering) of vehicles is a severe problem because vehicle emissions increase orders of magnitude and significantly impact the environment and human health. This study measured the emissions before and after representative approaches of tampering of two Euro 6 Diesel light-duty passenger cars, two Euro VI Diesel heavy-duty trucks, and a Stage IV Diesel non-road mobile machinery (NRMM) agricultural tractor. With tampering of the selective catalytic reduction (SCR) for NOx, the NOx emissions increased by more than one order of magnitude exceeding 1000 mg/km (or mg/kWh) for all vehicles, reaching older Euro or even pre-Euro levels. The tampering of the NOx sensor resulted in relatively low NOx increases, but significant ammonia (NH3) slip. The particle number emissions increased three to four orders of magnitude, reaching 6–10 × 1012 #/km for the passenger car (one order of magnitude higher than the current regulation limit). The tampered passenger car’s NOx and particle number emissions were one order of magnitude higher even compared to the emissions during a regeneration event. This study confirmed that (i) tampering with the help of an expert technician is still possible, even for vehicles complying with the current Euro standards, although this is not allowed by the regulation; (ii) tampering results in extreme increases in emissions.

Whole-body vibration exposure in unfavourable seated postures: apparent mass and seat-to-head transmissibility measurements in the fore-and-aft, lateral, and vertical directions

Mobile machinery operators are exposed to whole-body vibrations (WBV) and unfavourable postures which may lead to adverse effects on the spine. 14 subjects were exposed to WBV on a rigid seat without a backrest. They adopted nine different postures. Apparent mass and seat-to-head transmissibility were measured in the horizontal (X), lateral (Y) and vertical (Z) directions. They were compared to the reference posture from the ISO 2631-1 standard. Head and thorax inclinations in the sagittal plane had significant effects. An increase in the main resonant frequency together with a decrease in were observed in the Z direction. A second lower frequency peak also appeared ( for X, for Z). increased in the X and Z directions for increased in the X direction. Head and thorax inclinations in the frontal and the horizontal planes had weak or non-significant effects. Practitioner summary: Mobile machinery operators are exposed to whole-body vibration and unfavourable body posture. Laboratory measurements of the apparent mass and the seat-to-head transmissibility in the horizontal (X), lateral (Y) and vertical (Z) directions are presented for 9 postures relevant to the exposure at the driving position and to the effects of vibration on the spine.