The document discusses power screws, which are mechanical devices that convert rotary motion to linear motion and transmit power. Power screws offer advantages like large load capacity, compact construction, simple and easy design/manufacturing, precise motion, and low cost. Their disadvantages include poor efficiency and high friction. The document defines terminology for power screws like pitch, lead, diameter, helix angle, and describes single and double start threads. It also lists forms of threads including square, trapezoidal, ACME, and buttress threads.

1. Lecture by
Mr. B. B. Sangame
Machine Design-I
Terminology of power screw
Assistant Professor
Department of Mechanical Engineering
Shri Shamrao Patil (Yadravkar) Educational & Charitable Trust’s
Sharad Institute of Technology College of Engineering
Yadrav Ichalkaranji
Unit : Design of Power screws

2. Mr. B. B. Sangame
Power Screw
A power screw is a mechanical device used for converting rotary motion into
linear motion and transmitting power
A power screw offers the following advantages:
(i) Large load carrying capacity.
(ii) Compact construction.
(iii) Simple to design.
(iv) Easy manufacturing.
(v) Large mechanical advantage.
(vi) Precise and accurate motion
(vii) Smooth and noiseless operation
(viii) Low cost
(ix) Self locking property
The disadvantages of a power screw:
(i) Poor efficiency
(ii) High friction

3. Mr. B. B. Sangame
Power Screw
FORMS OF THREADS
1. Square threads 2. Trapezoidal threads 3. ACME threads
4. Buttress threads

4. Mr. B. B. Sangame
Terminology of power screws
Power Screw
(i) Pitch (p)
(ii) Lead (l)
(iii) Nominal Diameter (d)
(iv) Core Diameter (dc)
(v) Helix Angle (α)
(v) Mean Diameter (dm)
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2
(vi) Single start thread
(vi) Double start thread

5. Mr. B. B. Sangame