The worm and worm wheel is a very important mechanism in the field of Mechanical engineering. It has the ability to lift heavy loads with very little effort and keep the load raised and locked in a desired vertical position without any effort. The main objective of this experiment was to investigate the behavior of the worm and worm wheel gear set. Unfortunately, all the objectives of this experiment weren’t fulfilled in this session due to the following factors: The experiment was done only using a single starter worm The experiment was done by using only one gear which had 40 teeth.
The apparatus was recently repaired and consequently, it affected the experiment results to a certain extent. However, the experiment was fully conducted for a single started worm in mesh with a 40 teeth gear set. To start the experiment, the effort pulley and the load drum were loaded with appropriate weights and wound.
After the weights were loaded, a small downward pull was given to the effort hanger in order to overcome the static friction.
It was advised that this manual downward pull should be given by the same person and the Orca should be the same throughout the whole experiment since it could affect the experiment results adversely if done otherwise. And it was also advised that when releasing the effort, the effort hanger should be released from the same vertical height. Although the reason for this is not fully explainable, it can be assumed that this was either because the surface nature of the effort cord was not uniform or due to the number of rotations of the effort cord on the effort pulley that caused a slight difference in the friction between the cord segments.
After the experiment, readings for Applied load and Actual effort were obtained and tabulated. The tabulated data was then plotted to obtain a graph after further calculations. The graph was drawn for Actual effort (EAI) vs.. Applied load (F) to find the Law of the machine. During the experiment, there were few conflicts in opinions. Instances for such discrepancies were when at some attempts, the effort was able to lift the load with a mass very low than expected. The reason for this phenomenon is also not completely explainable since physical concepts such s static and dynamic friction are still not quite clearly understood.
But it could be assumed that this was due to human error because the initial downward pull was applied manually and there was a chance that the pull was not uniform in all instances of the experiment. In this worm and worm wheel gear set, the machine may not provide a continuous efficiency for all loads since there is a limit to its efficiency. The limiting efficiency for this apparatus can be termed as the reciprocal of the product of the velocity ratio and the slope of the graph drawn for the Law of the machine.