Practical Significance:
Many times there is a need to lift the loads and depending upon the type of load, intensity of load and other site conditions different lifting machines are used. Worm and worm wheel machine is used to lift heavy loads with constraint of space. After performing this experiment a Diploma Engineer will be able to decide the suitability of Worm and worm wheel depending upon the given lifting situation.
Relevant Course Outcomes:
Select the relevant simple lifting machine for a given purpose.
Practical Outcome:
Use Worm and worm wheel machine to lift load.
Minimum Theoretical Background:
Worm and Worm Wheel: A worm is square-threaded screw and worm wheel is a toothed wheel. Inthis machine, a worm and worm wheel are geared together maintaining their axes at right angles to each other. An effort wheel or pulley is attached to the worm coaxially so that effort can be applied through a rope wound over the pulley. A load is securely mounted coaxially on worm wheel and load is connected with a separate rope wound around the load drum.
For single rotation of effort wheel, effort traverses a distance=πD. For an n- threaded worm, worm pushes the worm wheel through one tooth during single rotation of effort wheel. If the total number of teeth in a worm wheel is T push of one tooth means the load drum traverses through (n/T) rotations.
Thus, when the radius of load drum is r, distance moved by the load = 2π x (n/T).
Therefore, the velocity ratio,
Practical Conduction:
Practical Related Questions:
1. Write four field applications of worm and worm wheel.
2. Can this machine is used to lift heavy loads?
3 State the given machine is reversible or not. Give reason.
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