jmw
Industrial
- Jun 27, 2001
- 7,435
There are several interesting threads here, and in the engineering history forum, that prompt this new post.
In engineering history the seacrh is on for the greatest engineering achievements and the greatest failures.
In this thread we have questions about "What is safe?" and there is another thread in this forum about the ethics of limited designs in "Design and Supply".
Here I want to give an example of bad design which I feel is potentially dangerous and inexcusable and to deiscover other's opinions on this and any other examples.
I won't name a brand or model as this may be leading into a litigeous area. Here I wanted to explore the engineering reaction to bad design.
My example is the particular make and model of rotary lawn mower my elderly parents purchased. Low cost and widly available I think there is an inherent dange in these and other designs that, because of circumstances, may not leave the manufacturers legally liable. You will see what I mean, but will, I think see that here the law is an ass.
The worst of this is that there are good designs out there and there is over a century of mower design history to call upon, so there is no excuse for bad design.
This is not about ground breaking, envelope pushing design innovations that can occassionally go wrong but which, overall, are but one valuable learning experience on the path to better things.
Here we have a simple excercise in taking modern design aids, modern manufacturing and the benefits of mass production and the acculmulated years of experience which should produce an excellent product at a very affordable price.
That is the expectation.
It is not a case of "you get what you pay for" because in every endeavour engineers are delivering better designs and more capability for lower prices.
The expectation is justifiable.
This product confounds the expectations:
For example,
[ul square][li]It has four wheels, all are outside the cutting path; you cannot mow verges except on a diagonal where one wheel floats in air.[/li]
[li] the path from the cutter to the grass collector is obstructed by several braces which presumably keep the mower deck walls from flexing: when the wind blows, or collapsing inwards due to the low pressure expected from the action of the cutter blade, if it moved fast enough, but which, because of the very low reving engine it doesn't; or simply from impact damage e.g. when struck by a foot (a real expectation due to the frustration created).[/li]
[li]The grass collector has vents in the bottom and sides but none in the top or back so the first collected cuttings block the air flow. [/li]
[li]The next cuttings block the throat. The collector requires emptying when only half full or less and the grass does not compact.[/li]
[li]It may be excellent on astro-turf or in the desert but on a moist english lawn grass that can grow an couple of inches in a week, forget it.[/li]
[li]OK, so when the first Japanese machines reached the UK they did discover serious problems with the cutters because their blade design was based on quite different low-silicate grasses, but that was decades ago.[/li]
[li]This grass collector can require emptying every ten to twenty feet or so and the throat needs clearing each time.[/li]
[li] it has a dead mans handle throttle so, after you've crippled yourself extracting the grass box from under the fixed rake handle bar, and discover there is no tumble home to the grass box such that half of the grass falls straight out onto the lawn as you remove it, the engine stops.[/li]
[li] The engine stop is supposed to be a safety feature but the frequent need to stop, empty the grass collector and clear the blocked throat means that it requires pull-cord staring every ten feet or so when used on some lawns.
The consequence is that operators simpley defeat the throttle safety with a piece of string, because the safety feature is childishly easy to defeat.[/li]
[li] Operators now can be seen emptying the grass box and clearing the throat of the mower with the engine running.[/li][/ul]
Such designs are potentially dangerous and, worse, avoidable. A better design should cost no more but am I alone in noting that many bad designs are prodiuced simply because they can charge so much more for better designs which cost no more to produce?
Where are the ethics in this? What engineer of any integrity can be party to such designs?
I wonder, just how many other inexcusable designs are there?
JMW
Eng-Tips: Pro bono publico, by engineers, for engineers.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
In engineering history the seacrh is on for the greatest engineering achievements and the greatest failures.
In this thread we have questions about "What is safe?" and there is another thread in this forum about the ethics of limited designs in "Design and Supply".
Here I want to give an example of bad design which I feel is potentially dangerous and inexcusable and to deiscover other's opinions on this and any other examples.
I won't name a brand or model as this may be leading into a litigeous area. Here I wanted to explore the engineering reaction to bad design.
My example is the particular make and model of rotary lawn mower my elderly parents purchased. Low cost and widly available I think there is an inherent dange in these and other designs that, because of circumstances, may not leave the manufacturers legally liable. You will see what I mean, but will, I think see that here the law is an ass.
The worst of this is that there are good designs out there and there is over a century of mower design history to call upon, so there is no excuse for bad design.
This is not about ground breaking, envelope pushing design innovations that can occassionally go wrong but which, overall, are but one valuable learning experience on the path to better things.
Here we have a simple excercise in taking modern design aids, modern manufacturing and the benefits of mass production and the acculmulated years of experience which should produce an excellent product at a very affordable price.
That is the expectation.
It is not a case of "you get what you pay for" because in every endeavour engineers are delivering better designs and more capability for lower prices.
The expectation is justifiable.
This product confounds the expectations:
For example,
[ul square][li]It has four wheels, all are outside the cutting path; you cannot mow verges except on a diagonal where one wheel floats in air.[/li]
[li] the path from the cutter to the grass collector is obstructed by several braces which presumably keep the mower deck walls from flexing: when the wind blows, or collapsing inwards due to the low pressure expected from the action of the cutter blade, if it moved fast enough, but which, because of the very low reving engine it doesn't; or simply from impact damage e.g. when struck by a foot (a real expectation due to the frustration created).[/li]
[li]The grass collector has vents in the bottom and sides but none in the top or back so the first collected cuttings block the air flow. [/li]
[li]The next cuttings block the throat. The collector requires emptying when only half full or less and the grass does not compact.[/li]
[li]It may be excellent on astro-turf or in the desert but on a moist english lawn grass that can grow an couple of inches in a week, forget it.[/li]
[li]OK, so when the first Japanese machines reached the UK they did discover serious problems with the cutters because their blade design was based on quite different low-silicate grasses, but that was decades ago.[/li]
[li]This grass collector can require emptying every ten to twenty feet or so and the throat needs clearing each time.[/li]
[li] it has a dead mans handle throttle so, after you've crippled yourself extracting the grass box from under the fixed rake handle bar, and discover there is no tumble home to the grass box such that half of the grass falls straight out onto the lawn as you remove it, the engine stops.[/li]
[li] The engine stop is supposed to be a safety feature but the frequent need to stop, empty the grass collector and clear the blocked throat means that it requires pull-cord staring every ten feet or so when used on some lawns.
The consequence is that operators simpley defeat the throttle safety with a piece of string, because the safety feature is childishly easy to defeat.[/li]
[li] Operators now can be seen emptying the grass box and clearing the throat of the mower with the engine running.[/li][/ul]
Such designs are potentially dangerous and, worse, avoidable. A better design should cost no more but am I alone in noting that many bad designs are prodiuced simply because they can charge so much more for better designs which cost no more to produce?
Where are the ethics in this? What engineer of any integrity can be party to such designs?
I wonder, just how many other inexcusable designs are there?
JMW
Eng-Tips: Pro bono publico, by engineers, for engineers.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
