(Solved): A contractor wants to investigate the production and cost differences of using a 7S blade on a D7 ...

A contractor wants to investigate the production and cost differences of using a $7\mathrm{S}$ blade on a D7H dozer or an S blade on an 824 dozer. The material is very sticky, and it is to be moved a distance of $200\mathrm{ft}$ from the beginning of the cut. The dozing is uphill on a $5\%$ grade. The operator will have average skill, the dozers have power-shift transmissions, and traction is assumed to be satisfactory. The site conditions will be good for visibility. The material weighs $106\mathrm{pcf}$ in the bank state. Job efficiency is assumed to be equivalent to a 55 -min hour. Calculate the direct cost of the proposed earth moving operation in dollars per bcy. Assume the O\&O cost for the D7 dozer is $\$95.00$ per hour and $\$86.00$ per hour for the 824 . The operator's wage for the 824 is $\$23.00$ per hour plus $40\%$ for fringes, workers compensation, and other benefits. The operator's wage for the D7 is $\$25.00$ per hour plus $40\%$ for fringes, workers compensation and other benefits. a. Which machine would you use on this job? b. It rains and the coefficient of traction of the 824 is now. 0.36 . The coefficient of traction for the D7 is 0.55 . Which machine would you use on this job? Problem \#2 What is the travel time for a scraper moving $19\mathrm{mph}$ over a distance of $3,100\mathrm{ft}$ ? Problem \#3 What is the travel time, in minutes, for a scraper moving $21\mathrm{mph}$ over a distance of 0.56 miles? Problem \#4 A contractor has both a 3-cy and a 5-cy shovel in the equipment fleet. Select a minimum size shovel that will excavate 450,000 bcy of common earth in a minimum 120 working days of $10\mathrm{hr}$ each. The average height of excavation will be 18 , and the average angle of swing will be 80 degrees. The 3 -cy shovel has a maximum digging height of $30\mathrm{ft}$ and the 5-cy machine's maximum digging height is $34\mathrm{ft}$. The efficiency factor will be a 50 -min hour. Appropriate size haul units can be used with either shove. How many days will it require to complete the work?