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Earthmoving, Excavating, and Lifting Equipment Selection
Published in Douglas D. Gransberg, Jorge A. Rueda-Benavides, Construction Equipment Management for Engineers, Estimators, and Owners, 2020
Douglas D. Gransberg, Jorge A. Rueda-Benavides
Coefficients of traction vary based upon the travel surface. They measure the degree of traction between the wheel or track and travel surface. Slick surfaces have lower coefficients of traction than rougher surfaces (assuming both surfaces are relatively level and flat). Coefficients of traction for rubber-tired vehicles range from 0.90 for a concrete surface, 0.20 for dry sand to 0.12 for ice. Typically, coefficients of traction tables are available in equipment performance handbooks. The better the traction generated by the piece of equipment on the travel surface, the shorter the travel time and less wear and tear on the piece of equipment. Simply stated, maximum tractive effort (drawbar or rimpull in pounds) equals the equipment weight multiplied by the coefficient of traction of the travel or work surface.
Caterpillar mechanical drive off-highway trucks
Published in Tad S. Golosinski, Val Srajer, Off-Highway Haulage in Surface Mines, 1989
Retarding with four wheel brakes is beneficial for other reasons. Weight is transferred to the front axle during downhill operation, unloading the rear tires. If the roadway is slick, the rear tires can lose traction at a given braking torque. With retarding brake torques being applied at all four comers, a lower torque at each comer is required to produce the same total braking effort, and the rear tires should not lose traction. In the retarding mode, both the 785 and 789 shut off fuel to the engine when the engine is over 1000 rpm. This significantly reduces fuel consumption on downhill hauls, or when returning to the pit. In service and secondary braking, the 785 and 789 easily pass the proposed SAE J1473 brake code at the maximum GVW - see figure 16. In addition, both have easily passed the brake tests specified by Alberta and British Colombia, Canada.
GripTester measurements and texture-friction relationship
Published in Eyad Masad, Amit Bhasin, Tom Scarpas, Ilaria Menapace, Anupam Kumar, Advances in Materials and Pavement Performance Prediction, 2018
R.B. Kogbara, E.A. Masad, K. Anupam, A. Scarpas
The skid resistance measurements were carried out using a GripTester. The device uses a measuring tire with 25.4 cm (10 in) diameter slick tread. The permissible speed range for the GripTester is 5–130 km/h but 50 km/h is the typical speed for highway testing. Hence, the GripTester employed is set to provide water at 10 liters/min, which yields 0.5 mm water film thickness for surface wetting, at 50 km/h speed. However, it does not permit surface wetting at less speeds. The pavement friction output (grip number) was collected at 5 m intervals in the outer wheel path of the lane. A global positioning system (GPS) in the GripTester-towing vehicle was used for geolocation of data points.
A review of the toxicology of oil in vertebrates: what we have learned following the Deepwater Horizon oil spill
Published in Journal of Toxicology and Environmental Health, Part B, 2021
Ryan Takeshita, Steven J. Bursian, Kathleen M. Colegrove, Tracy K. Collier, Kristina Deak, Karen M. Dean, Sylvain De Guise, Lisa M. DiPinto, Cornelis J. Elferink, Andrew J. Esbaugh, Robert J. Griffitt, Martin Grosell, Kendal E. Harr, John P. Incardona, Richard K. Kwok, Joshua Lipton, Carys L. Mitchelmore, Jeffrey M. Morris, Edward S. Peters, Aaron P. Roberts, Teresa K. Rowles, Jennifer A. Rusiecki, Lori H. Schwacke, Cynthia R. Smith, Dana L. Wetzel, Michael H. Ziccardi, Ailsa J. Hall
Hepatic exposure and effects of DWH oil were evident in some field-collected sea turtles, as bile metabolite levels were elevated (Ylitalo et al. 2017; Ylitalo, Collier, and Stacy 2015). Similar dose-dependent elevations in bile metabolites were also seen in both species in the surrogate study (Mitchelmore et al. 2015). Further, a rise in bile protein concentrations in snapping turtles exposed to 1,000 mg/kg slick A DWH oil suggested that there may have been reduced intake or assimilation of food (Mitchelmore et al. 2015). A 14 day-exposure to slick A oil at 1,000 mg/kg resulted in significant elevations in oxidative stress and antioxidant compensatory responses in the liver tissue in red-eared sliders evidenced as increases in total antioxidants and total, reduced, and oxidized glutathione levels. Only elevations in total antioxidant levels were evident in liver tissue of the snapping turtle, highlighting difference between turtle species (Mitchelmore et al. 2015). Interestingly, the lack of compensatory antioxidant responses may be the reason why there was evidence for oxidative damage in this species.
Longitudinal hydroplaning performance of passenger car tires
Published in Vehicle System Dynamics, 2021
Markus Maleska, Frank Petry, Duc Fehr, Wolfram Schuhmann, Martin Böhle
The indoor test rig records images of the tire footprint characteristics at a low velocity on a dry countersurface. During the laboratory measurement, the tire is rolling over a glass plate under which a camera records the contact area between the tire and the plate so that the geometric characteristics of the footprint can be determined. Besides, the tire is rolling over a pressure mat to obtain the footprint contact pressure distribution. The footprint geometry can be described, in addition to width and length, by net and gross area. The net area is the actual area of the contact between tire and road. The gross area is defined as the outlined enveloped area of the net area. Applying this definition to the case of a slick tire (a tire with a tread that has no sipes, no longitudinal or lateral grooves as well as no decorations), net and gross area are equal. Thus, the net-to-gross ratio for the area can be introduced as an additional measure.
A review on the impacts of connected vehicles on pavement management systems
Published in International Journal of Pavement Engineering, 2023
Mohammad Saleh Entezari, Amir Golroo
The proposed road weather information systems based on CVs observations were scrutinised in Table 5. The suggested systems were aimed at the development of EMDSSs or road-weather prediction models According to the table, there are three studies available with frameworks for converting vehicles’ systems data to input variables for road weather information systems. The data included status of wipers (to infer rain), traction control (to infer slick pavement), and headlights (to infer fog). Vehicle speed was also used to infer the present weather condition.in all the projects, weather data from CVs and traditionally-sourced weather data have been combined. Thus, ancillary data were used to complement and also to quality control CV observations.data on air temperature have been collected from vehicular observations in all the related studies (100%). Data on rain intensity and relative humidity were taken from vehicles’ sensors in 60% of the weather-related studies. Surface temperature and wind speed information were provided by the vehicles sensors in 40% of the weather-related studies.controlling the quality of CV observations based on sensor ranges, nearest vehicles, nearest fixed stations, and numerical weather models at the same time was proposed in only one research.