Concept explainers
In Ex. 14-5 use nitrided grade 1 steel (4140) which produces Brinell hardnesses of 250 core and 500 at the surface (case). Use the upper fatigue curves on Figs. 14-14 and 14-15. Estimate the power capacity of the mesh with factors of safety of SF = SH = 1.
EXAMPLE 14-5 A 17-tooth 20° normal pitch-angle helical pinion with a right-hand helix angle of 30° rotates at 1800 rev/min when transmitting 4 lip to a 52-tooth helical gear. The normal diametral pitch is 10 teeth/in. the face width is 1.5 in, and the set has a quality number of 6. The gears are straddle-mounted with bearings immediately adjacent. The pinion and gear are made from a through-hardened steel with surface and core hardnesses of 240 Brinell on the pinion and surface and core hardnesses of 200 Brinell on the gear. The transmission is smooth, connecting an electric motor and a centrifugal pump. Assume a pinion life of 108 cycles and a reliability of 0.9 and use the upper curves in Figs. 14-14 and 14-15.
Want to see the full answer?
Check out a sample textbook solutionChapter 14 Solutions
SHIGLEY'S MECH.ENGINEERING DESIGN-EBK>I
- A 21-tooth pinion rotating at 1000 rpmrpm meshes with a 33-tooth gear in a spur-gear reducer. Both pinion and gear are manufactured to a quality level of 9. A reliability of 0.9 has been specified and the transmitted tangential load is 2500 lblb. Conditions are such that Cm= 1.7. It is proposed that standard 25∘∘, full-depth teeth be used, with both pinion and gear hobbed from an AISI 4140 nitrided steel. The diametral pitch is 6, and the face width 2.000 inin. Suppose that the life of the pinion will be less than that of the gear, the lubricant bulk temperature does not exceed 250∘F∘F, both driver and driven devices are smooth-running, the gearset is external, gears made by conventional methods. Use the average value for the uncorrected surface-fatigue strength when choosing it from the appropriate table. Assume that the reducer is used for critical service applications. a)What is the dynamic factor (Cv) for the pinion? b)What is the AGMA Surface-Geometry Factor(I) for the pinion/gear…arrow_forwardA pair of straight teeth spur gear is to transmit 20kw when the pinion at 300rpm.the velocity ratio is 1:3.the allowable static stresses for the pinion and the gear material are 12MPa and 100MPa respectively.the service factor is 1.the pinion has 15 teeth and it's face width is 14 times the module.from the standpoint of strength only and taking into consideration the effect of the dynamic loading Determine; (A) module (B) face width (C) pitch circle diameter for pinion (D) pitch circle diameter for gear Tooth form factor;y=0.153_0.912÷no.of teeth Velocity factor;Cv= 3÷3+varrow_forwardA brass spur rotating at 600rpm drives a cast iron spur gear at a transmission ratio of 4:1.the allowable static stresses for the spur pinion and cast iron gear are 84MPa and 105MPa respectively.the pinion has 16 standards 20 degrees full depth involute teeth of module 8mm.the face width of both the gear and the pinion is 90mm. From the stand point of strength, calculate; (A) tangential load on the tooth (B) power transmittedarrow_forward
- A pair of gears with 20° full-depth teeth are to transmit 15hp at 1750 rpm of the 4-in pinion; velocity ratio desired is about mw= 4; intermittent service. Use a strength reduction factor of about 1.4, with the load at the tip and teeth carefullycut. A.Determine the diametral pitch, B. face width, C. and tooth numbers if the material is cast iron, class 25arrow_forwardA 57-tooth spur gear is in mesh with a 23-tooth pinion. The gearset transmits 125 hp at 1000 pinion rpm. Size the spur gears for a bending failure safety factor of at least 2 assuming a steady torque, 25∘ pressure angle, full-depth teeth, Qν = 9, an AISI 4140 steel pinion, and a class 40 cast iron gear. Part A Find the appropriate standard diametral pitch for the gearset. Part B Find the minimum required face width of the gears needed to satisfy the safety requirementsarrow_forwardCompute the contact stress number for the gear fain pair driven directly by an electrical motor. The driven machthe is concrete mixture with moderate shock, the other data are given below. Ks= 1.00, Km 1.21, Vt =1527 St/min, Av-11 Pd= 6, np= 1750rp.m, Np 20, No= 70, F=2.00/n Tp = 900ib, Dp= 3:333 in The material used for pioin an gear is Steelarrow_forward
- A steel shaft 800 mm long transmitting 15 kW at 400 r.p.m. is supported at two bearings at the twoends. A gear wheel having 80 teeth and 500 mm pitch circle diameter is mounted at 200 mm from theleft hand side bearing and receives power from a pinion meshing with it. The axis of pinion and gearlie in the horizontal plane. A pulley of 300 mm diameter is mounted at 200 mm from right hand sidebearing and is used for transmitting power by a belt. The belt drive is inclined at 30° to the vertical inthe forward direction. The belt lap angle is 180 degrees. The coefficient of friction between belt andpulley is 0.3. Design and sketch the arrangement of the shaft assuming the values of safe stresses as :τ = 55 MPa; σt= 80 MPa. Take torsion and bending factor 1.5 and 2 respectively.arrow_forwardA shaft subjected to bending moment varying from -200 N m to +500 N m and a varying torque from 50 N m to 175 N m. If material of the shaft is 30C8, stress concentration factor is 1.85, notch sensitivity is 0.95 reliability 99.9% and factor of safety is 1.5, find the diameter of the shaft. The load on a bolt consists of an axial pull of 10 kN together with a transverse shear force of 5 kN. Find the diameter of bolt required according to Maximum principal stress theory; Maximum shear stress theory; Maximum principal strain theory; Maximum strain energy theory; and Maximum distortion energy theory. Take permissible tensile stress at elastic limit = 100 MPa and poisson’s ratio = 0.3arrow_forwardThe client requires a single step-up spur gearbox to transmit a 10 kW power from a shaft rotatingat 1000 rpm, while the output speed must be 1700 rpm. The material for gear and pinion is 817M40and 655M13, respectively State the design specification considering the following design factors:1. Functionality2. Stressarrow_forward
- A double square thread power screw is to raise a load of 70 kN. The screw has a mean diameter of 33.375 mm and a pitch of 6 mm. The coefficient of thread friction and collar friction are 0.13 and 0.10, respectively. The collar mean diameter is 90 mm and the screw turns at 90 rpm. Which of the following is the torque required to raise the load without friction effect? Group of answer choices 66845 N-mm 133690 N-mm 236078 N-mm 334840 N-mmarrow_forwardA certain farm equipment which requires 2200 N-m torque at 708 rpm has a diesel engine that operates at 1601 rpm as its prime mover. A No. 60 roller chain with a total length of 60 pitches and a small sprocket with 23 teeth are to be used with an operating temperature to remain constant at 45 degree C. Determine (a) the no. of teeth of the larger sprocket, (b) the pitch diameter of the smaller sprocket in mm, and (c) the pitch diameter of the larger sprocket in mm. Express your answer in 3 decimal places.arrow_forwardA double square thread power screw is to raise a load of 70 kN. The screw has a mean diameter of 33.375 mm and a pitch of 6 mm. The coefficient of thread friction and collar friction are 0.13 and 0.10, respectively. The collar mean diameter is 90 mm and the screw turns at 90 rpm. Which of the following is the torque required to overcome the collar friction? Group of answer choices 630000 N mm 315000 N mm 819000 N mm 409500 N mmarrow_forward
- Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University PressMechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSONThermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
- Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEYMechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage LearningEngineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY