each part A - A weight of 1500 N must be lifted. What is the total required torque necessary to lift this weight? Give your answer in units of N m. Part B - if the available power to drive the screw is 1,011 Watts, determine the fastest speed at which the weight can rise. Give your answer in units of mm/s, Part C - The efficiency of the preceding power screw (expressed as a number between 0 and 1, not as a percentage) is ? Part D - Suppose a high-quality thrust bearing was used to eliminate the collar friction. The efficiency of the screw would now b

each part A - A weight of 1500 N must be lifted. What is the total required torque necessary to lift this weight? Give your answer in units of N m. Part B - if the available power to drive the screw is 1,011 Watts, determine the fastest speed at which the weight can rise. Give your answer in units of mm/s, Part C - The efficiency of the preceding power screw (expressed as a number between 0 and 1, not as a percentage) is ? Part D - Suppose a high-quality thrust bearing was used to eliminate the collar friction. The efficiency of the screw would now b

Refrigeration and Air Conditioning Technology (MindTap Course List)

8th Edition

ISBN:9781305578296

Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Publisher:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Chapter6: Fasteners

Section: Chapter Questions

Problem 12RQ

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A 5/8 inch diameter double-thread Acme power screw with a thread coefficient of friction of 0.1 is being used to raise a load of 2,404 Ib. How much does the load move in inches to two decimal places during one full revolution of the power screw ? Selected Answer: 0.08 Correct Answer: 0.25 0.01
Answer TWO QUESTIONS only. Only tables and charts are allowed Q1. A screw jack with a 1-in. double-thread Acme screw is used to raise a load of 4000 N. A plain thrust collar of 50-mm mean diameter is used. Coefficients of running friction are estimated as 0.12 and 0.09 for f and fc, respectively. (a) Determine the screw pitch, lead, thread depth, mean pitch diameter, and helix angle. (b) Estimate the starting torque for raising and for lowering the load. (c) Estimate the efficiency of the jack when raising the load.
Information about the clamp assembly in the figure is given below. Thread diameter 12 mm, root diameter 10.16 mm, pitch 1.5 mm, screw profile angle 2α=60, friction surface of table A diameter 10 mm, friction between plate A-screw end surface coefficient 0.15 and screw-nut friction coefficient 0.15 is given. If a hand force of 200N is applied to the vise arm, if applied, a) How much force is applied to the clamped part. b) Calculate the efficiency of the vise.
A full journal bearing has a nominal diameter of 60.0 mm, a bearing length of 30.0 mm and supports a load of 3200 N when running at the design speed of 3200 rpm. The radial clearance has been specified as 0.04 mm. An SAE 20 oil has been chosen and the lubricant supply system is capable of delivering the lubricant to the bearing at 60oC. Using the Raimondi and Body design charts;1.1 find the temperature rise of the lubricant, (19)1.2 the total flow rate required, (1)1.3 the torque required to overcome friction (3)1.4 and the power dissipated in the bearing.
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2. A cylinder with a nominal 2.5 inch ID, a 4.0 inch OD, and a 3.0 inch length is to be mated with a solid shaft with a nominal 2.5 inch diameter. The cylinder and shaft are made from steel, with Sy = 100 kpsi and E 30 Mpsi. The coefficient of friction for the steel interface is 0.7. = The maximum and minimum allowable diameters for both the cylinder hole and the shaft are given as Dmax=2.5012 inch, Dmin=2.5 inch; dmax=2.5028 inch, dmin=2.5021 inch (a) (b) Determine the maximum amount of torque that can be transmitted through this joint, assuming the shaft and cylinder are manufactured within their tolerances. Determine yielding condition for the cylinder, due to the stress from the interference fit. Use the Von Mises yielding theory.
1- A bush roller chain drive is used to transmit 4 kW of power from the driving shaft on a hydraulic motor runs at 1200 r.p.m to the driven shaft which runs at 350 r.p.m. The drive is required to operate continuously with drop lubrication and driven machine is such that load can be regarded as fairly constant. Design the chain drive by calculating leading dimensions, number of teeth on the sprockets taking into account that the available distance between the two shafts centers is 400mm + 4% no more no less.
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Q1) A start square (normal series) power screw of 40 mm nominal diameter is acted upon by an axial load of 50 kN. The outside and inside diameters of the screw collar are 40 mm and 20 mm respectively. The coefficient of friction for both thread and collar are 0.2. The screw rotates at 20 r.p.m. The allowable thread bearing pressure is 15 N/mm' and the shear yield strength is 70 N/mm?. By using the uniform wear theory, determine a) the dimensions of the screw and the height of the nut, b) the number of the threads of the nut which are in engagement with screw, c) the stresses in the screw and the nut, d) the power required to drive the screw and state if the design is safe or not.
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