Book : machine elements in mechanical design fifth edition by Robert L.Mott A pa
ID: 1718512 • Letter: B
Question
Book : machine elements in mechanical design fifth edition by Robert L.Mott A pair of spur gears with 20 full-depth, involute teeth transmits 1.25 hp while the pinion rotates at 1800 rpm. The diametral pitch is 20, and the quality number is A7 using the5 Edition (Qv-10 using the 4h Edition). The pinion has 24 teeth, and the gear has 72 teeth. The face width is 0.625 in. The input power is from an electric motor and the overload factor has been estimated to be desired to manufacture both the pinion and the from the same grade and heat treatment using SAE 4140 steel, through-hardened. Assume that no unusual conditions exist so that a service factor of 1.00 can be used. Design for a reliability of 0.999 and a design life of 10,000 hours. Determine the heat treatment specification for the pinion and gear using the material listed above (if it is possible). If it is not possible, state clearly why it is not possible. Compute and clearly identify all of the necessary parameters needed to solve this problem completely (40 points) th factor has be estimated to be 1.25. The drive is ao 1.25. The drive is a commercial enclosed gear unit. It is gear using solid blanks (no spokes) madeExplanation / Answer
Sin = BD/AB = (600 - 400)/(400 + 600) = 0.2
= 11.537°
Referring to FBD of sphere A (Fig a)
R2cos = 200
R2 = 200/cos11.537° = 204.1 N .......ANS
And R1 – R2sin = 0
R1 = 40.8N .......ANS
Referring to the FBD of sphere C [Fig. 6.82(b)],
Sum of forces parallel to inclined plane = 0
R4cos – 200cos45° = 0
R4 = 144.3 N .......ANS
Sum of forces perpendicular to inclined plane = 0
R4cos(45 – ) – R3cos45° = 0
R3 = 170.3N