Concept explainers
A power screw is 25 mm in diameter and has a thread pitch of 5 mm.
- (a) Find the thread depth, the thread width, the mean and root diameters, and the lead, provided square threads are used.
- (b) Repeat part (a) for Acme threads.
(a)
The thread depth for square threads.
The thread width for square threads.
The mean diameter for square threads.
The root diameter for square threads.
The lead provided for square threads.
Answer to Problem 1P
The thread depth for square threads is
The thread width for square threads is
The mean diameter for square threads is
The root diameter for square threads is
The lead provided for square threads is
Explanation of Solution
The Figure (1) shows the free body diagram square thread.
Figure (1)
Write the expression for the mean diameter.
Here, the mean diameter is
Write the expression for the root diameter.
Here, the root diameter is
Write the expression for the lead of the square threads.
Here, the lead is
Conclusion:
From Figure (1), obtain the thread depth of the square thread as,
Thus, the thread depth for square threads is
From Figure (1), obtain the width of the square thread as,
Thus, the thread width for square threads is
Substitute
Thus, the mean diameter for square threads is
Substitute
Thus, the root diameter for square threads is
Substitute
Thus, the lead provided for square threads is
(b)
The thread depth for Acme threads.
The thread width for Acme threads.
The mean diameter for Acme threads.
The root diameter for Acme threads.
The lead provided for Acme threads.
Answer to Problem 1P
The thread depth for Acme threads is
The thread width for Acme threads is
The mean diameter for Acme threads is
The root diameter for Acme threads is
The lead provided for Acme threads is
Explanation of Solution
The Figure (2) shows the free body diagram Acme thread.
Figure (2)
Write the expression for the mean diameter.
Write the expression for the root diameter.
Write the expression for the lead of the Acme threads.
Conclusion:
From Figure (2) obtain the thread depth of the Acme thread as,
Thus, the thread depth for Acme threads is
From Figure (2) obtain the width of the Acme thread as,
Thus, the thread width for Acme threads is
Substitute
Thus, the mean diameter for Acme threads is
Substitute
Thus, the root diameter for Acme threads is
Substitute
Thus, the lead provided for Acme threads is
Want to see more full solutions like this?
Chapter 8 Solutions
Shigley's Mechanical Engineering Design (McGraw-Hill Series in Mechanical Engineering)
- 1. A square-thread power screw has a major diameter of 32 mm and a pitch of 4 mm with double threads, and it is to be used in an application similar to the Figure. The given data include fc = 0.08, dc = 40 mm, and F = 6.4 kN per screw. (a) Find the thread depth, thread width, pitch diameter, minor diameter, and lead. (b) Find the torque required to raise and lower the load. (c) Find the efficiency during lifting the load.arrow_forward2- Give the true representation of screw thread from the following, and mark the reasons for the false. (4) (1) (5) ■ (3) كarrow_forwardConsider a thread callout of Dia 0.500-24 UNF-3A. Based on the information given, is this thread/screw an external (male) thread or an internal (female) thread?arrow_forward
- 1. Name some uses of threads. Give an example of each. NOTE: Screw Thread – A screw thread may be visualized as a flexible form, like a piece of string that has been wrapped around a cylinder, or the sides of the cylindrical hole, at a uniform rate of advance, producing a form known as a helix. It may also be considered as a raised form produced on the outside of a cylinder, or on the inside walls of a cylindrical hole after a thread-cutting operation has been completed.arrow_forwardWhat are the TPI and TPF of a part with end diameters of 3/4" and 1/2" and a taper length of 4.25"?arrow_forward(12) A turnbuckle connects two rods having %-16 UNC threads. The thread friction is 0.2. How much external torque is necessary to stress the rods 500lb if it is assumed that neither rod turns as the turnbuckle is tightened? The mean diameter of the threads is 0.335 in.arrow_forward
- A car jack uses a single square-thread screw to raise a known load. The major diameter and pitch of the screw and the thrust collar mean diameter are known. Running friction coefficients are estimated. Find: (a) Determine the thread depth and helix angle. (b) Estimate the starting torque for raising and lowering the load. . Schematic and Given Data: Load 50 kNarrow_forwardA screw jack mechanism is shown in the figure below (not drawn to scale). A belt drives a sheave that rotates the nut. The screw is a single-thread,1 1/2-4 ACME screw. Notice that a pin is used in a groove to prevent the screw from rotating. The sheave has a pitch diameter of 14 inches. The belt is driven by an electric motor (not shown) with a sheave pitch diameter of 2.8 inches at 1650 rpm. Determine the lifting speed of the jack. Determine the belt speed. Find the lifting speed (s) of the jack (in/min): Find the belt speed vb (ft/min):arrow_forward4. A square-threaded power screw has a mean diameter, dm = 1.75 in and a pitch, p = 0.875 in. The coefficient of thread friction is 0.10 and the collar friction is negligible. What horsepower is required to raise a weight of 3000 lbf at a rate of 20 ft/min?arrow_forward
- (9) A single thread trapezoidal metric thread has a pitch of 4mm &has a mean diameter of 18mm. It is used as a translation screw in conjunction with the collar having an outside diameter of 37mm & inside diameter of 27mm. Find the required torque in N-m to raise a load of 400kg, if the coefficient of friction is 0.3 for both threads & the collar.arrow_forwardIf root diameter is 9.5 mm and major diameter is 16 mm,for an internal thread, find Pitch.arrow_forwardA double-threaded power screw is used to raise a load of 5 kN. The nominal diameter is 60 mm and pitch is 9 mm. The threads are Acme type (20.15. Neglect collar friction, calculate :(a) the torque required to raise the load(b) the torque required to lower the load (c) the efficiency of the screw for lifting loadarrow_forward
- Precision Machining Technology (MindTap Course Li...Mechanical EngineeringISBN:9781285444543Author:Peter J. Hoffman, Eric S. Hopewell, Brian JanesPublisher:Cengage Learning