Cab Design Research Articles

Repeatability of a Checklist for Evaluating Cab Design Characteristics of Heavy Mobile Equipment

Risk factors associated with the development of musculoskeletal discomfort and disorders during the operation of heavy mobile equipment include whole-body vibration and awkward and sustained joint postures of the shoulders, neck, and trunk. Cab design may influence awkward postures of the joints, and task duration may influence duration of exposure to awkward and static postures and whole-body vibration. To reduce exposure to risk factors related to the interface between cab design and task, it may be necessary for manufacturers to address cab design. This study assessed the repeatability of a cab design checklist developed to evaluate various design characteristics that can influence exposure to risk factors for musculoskeletal discomfort. The ability of the cab design checklist to identify posture-related deficiencies of design was also assessed. The checklist was used by two administrators across 10 pieces of heavy construction equipment. Video analysis was performed to quantify postures of the neck, shoulder, and trunk; correlation analysis was used to determine whether specific questions from the checklist were associated with the identification of awkward postures. The repeatability assessment resulted in kappa coefficients ranging from 0.52 to 1.0 (good-to-excellent reproducibility) across each piece of equipment, and an overall kappa coefficient of 0.77 (excellent reproducibility) when considering all equipment together. Results from the correlation analysis showed that shoulder flexion posture was correlated with scores from the cab design checklist. However, results of the cab design checklist were not significantly correlated with shoulder abduction or awkward postures of the neck and trunk. Results suggest that the cab design checklist may be useful for identifying cab design characteristics that need further improvement and for identifying design characteristics that increase shoulder flexion. The strength of the repeatability assessment suggests that outcomes of the cab design checklist administered by different individuals may be consistent, independent of the type of equipment being assessed.

Whole-body vibration and ergonomic study of US railroad locomotives

US locomotive operators have exposure to multi-axis whole-body vibration (WBV) and shocks while seated. This study assessed operator-related and ergonomic seating design factors that may have confounding or mitigating influence on WBV exposure and its effects. Vibration exposure was measured according to international guidelines (ISO 2631-1; 1997); ergonomic work place factors and vibration effects were studied with a cross-sectional survey instrument distributed to a randomly selected group of railroad engineers ( n = 2546 ) and a control group; and during vehicle inspections. The survey response rate was 47% for the RR engineers ( n = 1195 ) and 41% for the controls ( n = 323 ). Results of the mean basic vibration measurements were for the x, y, z-direction and vector sum 0.14, 0.22, 0.28 and 0.49 m/s 2 respectively; almost all crest factors (CF), MTVV and VDV values were above the critical ratios given in ISO 2631-1. The prevalence of serious neck and lower back disorders among locomotive engineers was found to be nearly double that of the sedentary control group without such exposure. Railroad engineers rated their seats mostly unacceptable regarding different adjustment and comfort aspects (3.02–3.51; scale 1=excellent to 4=unacceptable), while the control group rated their chairs more favorably (1.96–3.44). Existing cab and seat design in locomotives can result in prolonged forced awkward spinal posture of the operator combined with WBV exposure. In a logistic regression analysis, time at work being bothered by vibration (h/day) was significantly associated with an increased risk of low back pain, shoulder and neck pain, and sciatic pain among railroad engineers. Customized vibration attenuation seats and improved cab design of the locomotive controls should be further investigated.

Ergonomics in mining.

Like other areas of occupational health and safety (OHS) ergonomics is evolving and becoming more integrated into overall work management systems. As we learn more about the complex interaction between psychosocial and physical factors in the aetiology of work-related illness and injury the more we rely on managers to 'get it right' if we are to prevent these conditions. Risks to health and safety in the mining industry posed by longer shift lengths, higher work loads, less task variation and decision latitude have not really been well researched. Heavy physical workloads and stresses are still areas of concern, but are likely to be intermittent rather than constant. Recent research confirms current thinking rather than shedding new light on the subject. The contribution of slips, trips and falls and increasing age of miners to manual handling injuries is still not clear. In some cases sedentary work and the operation of machinery has completely replaced heavy physical work. The issues of machinery design for operations and maintenance and whole-body vibration exposures when operating machines and vehicles are becoming more critical. The link between prolonged sitting, poor cab design and vibration with back and neck pain is being recognized but has yet to be addressed in any systematic way by the mining industry. On the plus side some mining companies have well-developed participative approaches to problem solving and these need to be extended to areas such as ergonomics.

Aspects to improve cabin comfort of wheel loaders and excavators according to operators

Comfort plays an increasingly important role in interior design of earth moving equipment. Although research has been conducted on vehicle interiors of wheel loaders and excavators, hardly any information is known about the operator's opinion. In this study a questionnaire was completed by machine operators to get their opinion about aspects which need to be improved in order to design a more comfortable vehicle interior. The results show that almost half of the operators rate the comfort of their cabin “average” or “poor”. According to the operators, cab comfort of wheel loaders can be increased by improving seat comfort. Besides improving seat comfort, cabin comfort of excavators can be improved by changing the cab design (including dimensions, ingress/egress), view, reliability, and climate control.

Simple Finite Element Model with Beam Elements for Panel Part of Spot-Welded Frame-Panel Structure.

The high quality of the cab design and the vibration reduction of the cab are needed for the vehicle type construction machinery. As these countermeasures, the structure analysis and vibration analysis are carried out by large-scale CAE modeled with the shell elements in detailed design stage. But, when the design change is required in the evaluation using the CAE in detailed design, we have to make large-scale CAE model again. In the result, the prolongation of the development time and the increase of the calculation cost are caused. From such background, it is necessary to be simulated the strength and the vibration of the cab at the good accuracy in the conceptual design stage in order to carry out the cost reduction of the development and shortening development time. Then, the object of our study has been established the simple finite element model based on the beam elements for carrying out CAE in conceptual design stage in the design field easily. We have studied the evaluation method of torsional rigidity for the spot-welded frame which had been difficult to be calculated, and have been modeled the frame part of the cab with beam element. In this paper, we present the simple FE model with the rhombic beam elements for the panel part. We can establish the simplified FE model of the cab for static analysis and eigenvalue analysis.

117 建設機械キャブの概念設計用有限要素モデルの提案 : スポット溶接によるフレームーパネル構造のビーム要素を用いた有限要素簡易モデル(OS1-4 材料・構造体の変形解析)(OS1 材料の力学・疲労・破壊現象)

The finite element model using the simple beam element is proposed in order to predict the vibration from the stage of conceptual design of the construction equipment cab, and it carries out the improvement in the development initial stage, for the frame part, the torsional rigidity of the spot-welded frames was evaluated by simplified estimation method in order to calculate its value. And, the panel part in the cab constitutes the frame-panel structure by the spot welding. Second, in order to express the frame-panel structure by the spot welding well and be possible to use easily without depending on the experience in the design field, the model which replaced the panel part with the beam element was proposed. Finally, to verify that the finite element model of the cab using the beam element which can carry out the modeling without depending on the experience proposed in this study is possible to be applied to both the strength design and dynamic design, the structure analysis and the eigenvalue analysis were carried out. Consequently, the effectiveness of this model was confirmed by comparing these analysis results with experimental result.

The Robust Design for Acoustic Characteristic Modification with Taguchi Method. Analysis on Booming Noise Reduction in Heavy Duty Truck Cab.

Structural-acoustic analysis was performed in order to reduce booming noise due to floor panel vibration in heavy duty truck cab. Usually a common cab is used for various truck configurations. Therefore, a robust cab design which allows reduction f booming noise under various cab excitation forces is deemed to be important. As a first step towards this goal, finite element model of a cab floor panel and bounday elment model of a cab cavity were created, and the good correlation of booming noise between the simulation and excitation test was confirmed. In order to propose a rubust cab design, Taguchi Method was applied for a design parameter sstudy of the floor structure. This paper describes the method which can evaluate the effect of design parameters quantitatively with the ratio of main effect variance and interaction variance between main effect and excitation frequency. The parameters for noise reduction over a wide frequency range and paramers for noise reduction at a specified frequency can be discriminated with this method.

Effect of frame flexibility on the ride vibration of trucks

The aim of the paper is to study the ride vibration behaviour of trucks and in particular the effect of including a flexible frame. The work is a theoretical investigation and concentrates on the ride comfort, cargo protection, structural integrity and vehicle safety. The road surface irregularities are represented as stationary Gaussian random excitations. To analyse the vehicle dynamic responses, the spectral analysis technique has been used and the driver acceleration reponses have been weighted according to the ISO ride comfort techniques. To study the effects of the frame flexibility, the truck frame has been modelled using the FEM (finite element method) and its modal properties have been calculated. An explanation of the modal superposition theory is given and the possibility of incorporating this theory with Lagrange's equations for modelling a truck containing flexible subsystems is discussed and applied. Numerical results are presented for the truck, including power spectral densities and root mean square values of the vehicle dynamic response variables. The results show that there is good agreement with the previous experimental published work and that the modelling technique established is very powerful and economical for the analysis of complex vehicle structures. From comparison of the responses of the rigid and flexible body models it has been found that the frame flexibility strongly affects the accelerations of both the driver and the truck body. Therefore, it is critical that frame flexibility effects are taken into account in the design of primary, cab and engine suspension systems.

Evaluation Method for Torsional Rigidity of the Flame having Spot Weldings. 2nd Report. Expression of Torsional Rigidity.

The control of vibration level which an operator is exposed is the focus of recent attention towards the improvement of quality of vehicle-type construction machinery. Especially in the stage of the concept design for this type of machinery, designers have been investigating the vibrational dynamic behavior of a cab using simplified finite elements to reduce the vibration level to which the operator is exposed. However, because the cab has been formed by spot-welded and pressed thin steel plates, and designers have not been able to evaluate its torsional rigidity precisely without an experimental approach, evaluation errors in the model have been a hindrance to the development of a cab from the viewpoint of vibration control and reliability. Therefore evaluation techniques are required in the engineering field of cab design to establish an appropriate model of its structure. In this paper, we suggested to correct the torsional rigidity, that was calculated on the assumption that the beam having spot weldings had a closed section, in order to determine the rigidity of the semi-open section. In order to determine this correction coefficient using values representing the structure of a beam having spot weldings, we obtained relationship between the correction coefficient and the values representing the structure and to predicted the correction coefficient with an expression of multiple regression analysis.

Evaluation Method for Torsional Rigidity of Flame having Spot Weldings. 1st Report. Simplified Torsional Rigidity Analysis with FEM.

The control of vibration level to which an operator is exposed is the focus of recent attention towards the improvement of quality of vehicle-type construction machinery. Especially in the stage of the concept design for this type of machinery, designers have been investigating the vibrational dynamic behavior of a cab using simplified finite elements to reduce the vibration level to which the operator is exposed. However, because the cab has been formed by spot-welded and pressed thin steel plates, and designers have not been able to evaluate its torsional rigidity precisely without an experimental approach, evaluation errors in the model have been a hindrance to the devolopment of a cab from the view point of vibration control and reliability. Therefore evaluation techniques are required in the engineering field of cab design to establish and appropriate model of its struture. In this paper, we tried to use finite element method in order to compute the torsional rigidity values of some spot-welded frames. As a result, it was made clear that its method was useful.

Anthropometry of the Hong Kong male and the design of bus driver cabs

This study investigated the proposition that the crabs of buses imported into Hong Kong were not suited to the anthropometric characteristics of the local Chinese bus drivers. A ‘recommended’ cab design was derived from static anthropometric data; relationships between pedals, steering wheel and seat, and the range of seat adjustments were specified. Overall static anthropometric data were available but additional data had to be estimated by constructing manikins based on the available Hong Kong static data with joint positions derived from data for the US male population. Seven bus cab designs in current use were compared with the ‘ recommended’ design. None of them satisfied all the ‘recommended’ design specifications, the most serious deviations being the excessive height of the seat above the floor and pedals, and insufficient lateral separation between the pedals.

Describing Truck Driver Eye, Head, Stomach, Knee and Seat Locations in Heavy Truck Space

Photogram metric data collected in the SAE U.S. Truck Driver Anthropometric and Workspace Study were used to develop functional workspace models to describe where truck driver eyes, heads, stomachs, knees and seats were located in vehicle space. These models describe the probabilistic location in heavy truck space of the body landmarks of populations of truck drivers with various percentages of males and females as a function of vehicle packaging parameters. These models can be used to determine visual accommodation, head clearances, clearance between the stomach and steering wheel, knee clearance to the instrument panel surface and the location and amount of seat travel necessary to accommodate certain percentages of users with a certain cab design. Models were developed for truck driver populations with 50%/50%, 75%/25%, 90%/10% and 95%/5% male to female ratios. This distribution of models allows the designer to determine accommodation for several potential user groups.

Innovation in the United Kingdom tractor industry

This paper examines the pattern of technological innovation that has characterised the United Kingdom Tractor Industry over the past 25 years. The conclusion that competition in this industry has been marked by continuous incremental innovation is derived from an empirically-based technical change index as well as detailed case studies of the innovation process in hydraulics, transmission and cab design. The technical change index of tractor performance over the years 1965 to 1975 shows an increase of approximately 30% in overall tractor performance despite the fact that no radical innovation has taken place during this period. The prevalence of incremental innovation in the Tractor Industry is discussed in relation to a theoretical model of technological innovation developed by Utterback and Abernathy. It is argued that the Tractor Industry in the UK is technically more dynamic than one would expect from the classification scheme suggested in this model.

Locomotive cab design development. Volume I. Analysis of locomotive cab environment and development of cab design alternatives : Robinson, J., Piccione, D., and Lamers. G. Interim report Oct 1974 – Apr 1976. Oct 1976, 203 pp; abstr in Government Reports Announcements (Report No PB-262 976/4GA)

Locomotive cab design development. Volume I. Analysis of locomotive cab environment and development of cab design alternatives : Robinson, J., Piccione, D., and Lamers. G. Interim report Oct 1974 – Apr 1976. Oct 1976, 203 pp; abstr in Government Reports Announcements (Report No PB-262 976/4GA)

The Evolution of the CSV Water Tender and its Safety Cab

The current commercial situation, the Home Office standards, and the trends in water tender design are outlined. The aims of a fire appliance cab designer are examined and the reasons for the decision to develop a 6 man crew safety cab are explained. The current and proposed commercial vehicle and bus legislation was examined and found to be not directly relevant to Water Tenders. A series of fundamental safety standards were evolved and the CSV cab was designed to meet these standards. The non-structural aspects of the cab design are discussed. The successful cab testing programme is described.

The Analysis and Design of a Fire Engine Safety Cab Using Finite Element Methods

A three dimensional structural collapse analysis computer program is described, and illustrated by reference to a safety vehicle structure analysed and designed using the program. The particular problems of large displacements and material non-linearity are accounted for, and a method of estimating the permanent set which results after impact is described. Based on an incremental formulation of the conventional finite-element method, the computer program is capable of tracing the complete load deflection characteristics of a structure up to and beyond the point of collapse.

Commercial-Vehicle Cabs: Design for Packaging, Access and Visibility

The contents of this paper were originally prepared for a contribution to a conference on ‘Design of commercial vehicle cabs in relation to the driver's environment’, held on 26th April 1973. The information contained in the address by the author was considered of general interest and value to the commercial-vehicle industry. The paper is aimed at providing guidance in the derivation of commercial-vehicle cab design with particular reference to packaging, accessibility and visibility. Certain conflicting requirements, design problems and solutions are discussed and the author's observations on some of the possible future trends in cab design are included.