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Sheet Power Screw

The document outlines a series of mechanical design problems related to power screws and their applications in various scenarios, including calculations for hand wheel diameter, motor power, and force required using spanners. It includes specific parameters such as diameters, pitches, loads, and coefficients of friction for each problem. The context is set within an academic framework for a Mechanical Element Design course at Modern University for the 2024/2025 academic year.

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aheltaweel2004
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33 views2 pages

Sheet Power Screw

The document outlines a series of mechanical design problems related to power screws and their applications in various scenarios, including calculations for hand wheel diameter, motor power, and force required using spanners. It includes specific parameters such as diameters, pitches, loads, and coefficients of friction for each problem. The context is set within an academic framework for a Mechanical Element Design course at Modern University for the 2024/2025 academic year.

Uploaded by

aheltaweel2004
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Modern University

For Information and Technology Academic year 2024/2025


Department: Mechanical Department Semester spring 2025
Specialization: Mechatronics Program
Power Screw Sheet
Subject: Mechanical Element Design Code: MENG 212
Lecturer: Dr.Waleed Wahba
Assistant Lecturer: Eng. Sarah Afifi

1. A vertical screw with single start square threads of 50 mm mean diameter and
12.5 mm pitch is raised against a load of 10 KN by means of a hand wheel, the
boss of which is threaded to act as a nut. The axial load is taken up by a thrust
collar which supports the wheel boss and has a mean diameter of 60 mm. The
coefficient of friction is 0.15 for the screw and 0.18 for the collar. If the
tangential force applied by each hand to the wheel is 100 N, find suitable
diameter of the hand wheel.

2. An electric motor driven power screw moves a nut in a horizontal plane against
a force of 75 KN at a speed of 300 mm/min. The screw has a single square thread
of 6 mm pitch on a major diameter of 40 mm. The coefficient of friction at screw
threads is 0.1. Estimate power of the motor.

3. A square threaded bolt of mean diameter 24 mm and pitch 5 mm is tightened


by screwing a nut whose mean diameter of bearing surface is 50 mm. If the
coefficient of friction for the nut and bolt is 0.1 and for the nut and bearing
surfaces 0.16, find the force required at the end of a spanner 0.5 m long when
the load on the bolt is 10 KN.

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4. A vertical two start square threaded screw of a 100 mm mean diameter and 20
mm pitch supports a vertical load of 18 KN. The axial thrust on the screw is
taken by a collar bearing of 250 mm outside diameter and 100 mm inside
diameter. Find the force required at the end of a lever which is 400 mm long in
order to lift and lower the load. The coefficient of friction for the vertical screw
and nut is 0.15 and that for collar bearing is 0.20.

5. The spindle of a screw jack has a single start square thread with an outside
diameter of 45 mm and a pitch of 10 mm. The spindle moves in a fixed nut. The
load is carried on a swivel head but is not free to rotate. The bearing surface of
the swivel head has a mean diameter of 60 mm. The coefficient of friction
between the nut and screw is 0.12 and that between the swivel head and the
spindle is 0.10. Calculate the load which can be raised by efforts of 100 N each
applied at the end of two levers each of effective length of 350 mm. Also
determine the efficiency of the lifting arrangement.

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