S13 Design and Analyse Basic Mechanical Systems
Initial skills rating **
September 2011
Initial Skills Rating **
I do have some understanding of mechanical systems as I did train as a mechanical engineer and worked as a mechanical design draughtsperson for eleven years. I would like to put more stars here but it is such a long time since I used any of this knowledge I do not feel I can talk about it in a useful way. I need to refresh my memory.
10th March 2012
We have had a couple of taught lessons on mechanical systems and the knowledge felt familiar. However I would say although I would have covered all of this as an apprentice on day release to college a lot of it would never have been used since. My apprenticeship was many years ago and I needed the refresher. Now that I have had a refresher I am feeling I want to do some more work in this area to support the learning. I want to be so confident when I am working with basic mechanical systems that I do not make mistakes. Today I started writing up my notes and I was not happy with them all. So I have been reading about levers and types of
motion from many different sources until I felt confident that I could identify different types of motion and classes of levers. Now I will attempt to record my enhanced knowledge.
Motion ***
Motion is the action or process of moving position or changing place. Machines and mechanisms can be described by the type of motion they produce of which there are four types of motion.
Linear motion – motion in a straight line
Reciprocating motion – linear motion continually going backwards and forwards
Rotary motion - motion in a circle or arc around a fixed point
Oscillating motion – motion scribing an arc continually going backwards and forwards
When I came to write up my notes I could not understand why I had writen cars and trains have linear motion because cars can move in any direction the driver likes to take them and trains can travel on curved tracks. I now realise cars and trains do not move about a fixed centre which is why their movement is described as linear. I also questioned the movement of things like conveyor belts and escalators as although these move continually they do not move continually in a rotary motion or linear motion but both together. I now understand that these machines convert rotary motion to linear motion. The movement of the divers are rotating and the conveyor belt is for most of the part moving in a linear motion.
Linear motion – motion in a straight line
Reciprocating motion – linear motion continually going backwards and forwards
Rotary motion - motion in a circle or arc around a fixed point
Oscillating motion – motion scribing an arc continually going backwards and forwards
When I came to write up my notes I could not understand why I had writen cars and trains have linear motion because cars can move in any direction the driver likes to take them and trains can travel on curved tracks. I now realise cars and trains do not move about a fixed centre which is why their movement is described as linear. I also questioned the movement of things like conveyor belts and escalators as although these move continually they do not move continually in a rotary motion or linear motion but both together. I now understand that these machines convert rotary motion to linear motion. The movement of the divers are rotating and the conveyor belt is for most of the part moving in a linear motion.
Examples of linear motion:
Cars, trains, lorries, bycycles, drawers, drawer runners,the table on a pillar drill, paper trimmer and
lifts (because they travel in increments of straight motion),
Examples of reciprocating motion:
Fret saws (also known as reciprocating saws), handheld, jig saw blade, sewing
machine needle, pistons
Examples of rotary motion:
Wheels, roundabouts in a play park, spinning top, drills, washing machine, tumble dryer, fans, food mixer, food blenders, gears and bicycle pedals, cement mixers, ferris wheel or the London Eye.
Examples of oscillating motion
Pendulum, swing, see- saw, Newton’s cradle
Educational videos ****
I have a copy an educational video on my computer. It is really good to dip into just to refresh my memory. It has some lovely examples that trigger my brain into finding more examples. I thought wind turbines was a lovely example of rotary motion. I am sure I will refer back to this in the future.
I was always conscious that I missed the beginning of the taught session where our tutor showed a Youtube clip on differential gears.Now that I am much more computer literate and computer trusting I know where and how to find what I am looking for. I would have settled for anything that gave a clear;