Technology

Table of Content


Cover Page ……………………………………………………………….………..Page 1
Title of Experiment…………………………………………………………………Page 1
Objective..…………………………………..……………………………………...Page 2
Labeled Schematic Diagrams …………………………………………………...…Page 3
Digital Photos ………………………………………………………………..…….Page 4
Table of Contents .…………………………………………..…………………..…Page 6
Answers to Questions………………………..…………………………………..…Page 7
Conclusion ………………….…………………………………………………...…Page 9
Internet Research ….………………………..………………………………......…Page 10














Answers to Questions

1. When the Counter moved from a reading of zero to the number of turns (approximately 0.8 Turns) recorded in the experiment, calculate the number of turns made by Output Shaft “C”, and the number of turns made by Input Gear A. by using the Differential Gear Formula. Note that when the hand wheel initially turned Gear A, that Gear B did not turn (number of turns of B equal to zero) because of the friction of the motor, and worm and worm wheel.

(A+B)/2 = C
A= 0.8 Turns
B = Zero (Held by motor)
(A+B)/2 = (0.8+0)/2 = 0.4
C = 0.4 Turns

2. How do the readings on the Counter compare to the number of turns of Gear A, which is the Disturbance to the System.

The Disturbance caused by Gear A turning 0.8 turns, resulted in Shaft C turning 0.4 turns. The Mechanical Counter, because of the speed multiplier, will read (2 * C) = (2 * 0.4) = 0.8 Turns. This is the same as the number of turns of A, which was the Disturbance.

3. Why was a 1:2 gear ratio (speed multiplier) used between Output Shaft “C” and the counter?

This gear pair is a “speed multiplier” and therefore the counter will read twice as many turns as are made by the cam.

4. The motor is wired such that Gear B turns in the opposite direction of Gear A. Calculate the number of turns of Gear B in order that the counter count backwards to read zero and that the flag on Shaft “C” return to the horizontal position. Note that while the motor is turning, the hand wheel is held fixed and therefore the number of turns of Gear A is at this time equal to zero.

In order to counteract the Disturbance caused by Gear A, the input handle is now kept from moving such that A does not turn [A= 0], and Gear B must now turn 0.8 turns in the opposite direction of gear A

5. What would happen to the position of the flag if the motor did not turn itself off automatically?
The flag will rotate.
6. Calculate the Train Value, TV, of the two-stage speed reducer gear train from the output of the motor to Gear B.
TV = (1/60)*(72/96) = 0.0125
7. Knowing the value of TV and the number of turns of Gear B, calculate the number of turns made by the motor.
TV = Output Turns/Input Turns
Input Turns = Output Turns/TV
Input Turns = 0.8 Turns/0.0125 = 64 Turns
Motor Turns = 64 Turns

8. In terms of mechanical Power Flow it was necessary to maintain a constant load on the hand wheel in order that the flag return to the horizontal position. From your observation of what happened when the handwheel was released during operation, what analogy can be made to an “Electrical Principle” and Least Resistance?

If input handle is not held when motor is running, Power will follow the path of least resistance, and the handle will rotate. The counter and shaft “C” will not move until the input handle is restrained.

9. Referring to the initial definition of an Automatic Feedback Control System, for this experiment what would represent the Input (Command), Output (Response) and the Disturbance, and what component makes a comparison between the Input (Command), and Output (Response), which then gives an Error signal?

The “Command” is that the Flag on the Output Shaft be in the horizontal position. A Disturbance to the System happens when the Input Handwheel rotates Gear A, moves the Flag and automatically starts the cycle. When disturbed, the Cam makes a Comparison of the Input (Command) and Output (Response), closes the Normally Open (NO) Switching Contacts of the Limit Switch and sends a signal to start the Motor. The Motor turns the Differential Gear Train. The Indicating Flag will return to the horizontal position, the Counter will countdown to zero, the Switching Contacts will open and then the Motor will stop awaiting the next Disturbance.
CAM makes Comparison between Input and the Output and sends "Error Signal” to the Motor.

10. Explain another application of how a Differential could be used in a control