HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
williamlweaver
User Rank
Platinum
Planned Obsolescence
williamlweaver   5/21/2012 8:09:03 AM
NO RATINGS
*** DISCLAIMER: My wife is a former retail employee of Sears. We used to own Sears stock. ***

After owning two lawnmowers from Sears, we finally switched to another brand sold by Home Depot. In my opinion I suspect Sears Corporate managers received their MBAs from the MIT Sloan School of Management. Alfred P. Sloan is famous for developing the design policy of "planned obsolescence". I was consistently wearing out parts on our Sears products under normal use --- they were often made out of incompatible materials (such as metal on polymer here) and I spent most Saturdays making a trip to the mall to make a "spare parts" run. We even have a Sears Hardware store in our town that is primarily a Sears Spare Parts store. This past week I lost the thermal fuse on our Sears dryer (understandably consumable). Sears had it in stock at a spare parts depot an hour drive from my home for $20.21. Amazon sells it for $3.95.

Sometimes it is not the Designers' or Engineer's fault for shoddy products. It can also result from a corporate culture that designs for obsolescence. Which is poetic justice for our local Sears at the mall which closed this past month. I hope KMart has the wherewithal to digest their 2005 acquisition of Sears and change some of the outdated culture... 

 

GlennA
User Rank
Gold
Re: Planned Obsolescence
GlennA   5/21/2012 8:42:39 AM
I would include this in with Quality Junk.  The lawnmower met the Quality specifications, but mating metal gearing to plastic was a way to make the product 'cheaper', having gone past 'less expensive'.

I don't know what size your yard is.  The design may have been good enough for a postage stamp size yard that is cut every-other week.  But then why would you need a self-propelled mower for such a small yard.  Maybe the working theory was that you were supposed to buy a ride-on mower for the size of your yard.  As you said, you don't know who was the author of the specifications.

naperlou
User Rank
Blogger
Re: Planned Obsolescence
naperlou   5/21/2012 10:21:42 AM
Well, it may be planned obsolence, but the material may not matter as much as the design.  I owned a 1969 MGB with wire wheels.  That was a fun car.  The only problem was that the wire wheels had a hub with splines that fit in a splined shaft on the axle.  The splines were fairly fine.  This did not work well.  Even those all these parts were fairly stong metal castings, the splines would wear out.  There was a central wheel nut holding this on.  It was left hand thread.  This worked for the left wheel, but on the right side the nut would unscrew under breaking.  It was wild.  On the way back home from a trip once I had to avoid using the breaks.  I downshifted and used the parking break if I could.  At each stoplight my passenger would jump out with the wheel nut wrench and the lead hammer to tighten the nut.  I wonder what the other drivers thought. 

The real point of the story is that the material does not matter as much as the design.  They probably could have made the lawn mower work with a different plastic or gear shape.  On the other hand, I wonder how much they saved from using plastic for this gear in the first place?

NadineJ
User Rank
Platinum
Re: Planned Obsolescence
NadineJ   5/21/2012 12:45:56 PM
NO RATINGS
That's a good point naperlou.  Saving money is the key.  From my experience working directly with majour retailers, planned obsolescence isn't part of the conversation.  It's all about cost and profit margin.

We're still in a disposable society and consumers want what they perceive as value-works well enough and costs less.

Rob Spiegel
User Rank
Blogger
Re: Planned Obsolescence
Rob Spiegel   5/21/2012 3:12:10 PM
On this particular instance, I wonder if the company didn't anticipate that users would use the mower's driver control to create a slower speed than fully engaged. Sounds like the user was adjusting the engagement lever to slow down the mower, which would mean the gears would grind insted of engaging. 

armorris
User Rank
Platinum
Re: Planned Obsolescence
armorris   5/22/2012 9:47:24 AM
NO RATINGS
As a matter of fact, I had been partially engaging the drive in order to slow down the forward motion of the mower, but that is normal use in my opinion. The engine has a governor and no throttle.

About 45 years ago, in high school, I worked part time for Sears as a TV repairman. Back then, they repaired only Sears products, and at reasonal cost.

My boss told me that Sears made their money on sales and that the service department was the "butt-hole" of the sales department. But if you let the butt-hole get stopped up, you'll see how much it's worth.

I wonder where the butt-hole is now? :-)

Rob Spiegel
User Rank
Blogger
Re: Planned Obsolescence
Rob Spiegel   5/22/2012 10:09:13 AM
NO RATINGS
That's pretty graphic, Armorris. I agree, the partial engagement is a very natural way of managing the speed of the mower. As a kid a mowed a ton of lawns, and you can't manage a lawn cut with a fully engaged drive (except on long straight stretches). With a fully engaged drive, you can dig ruts into the lawn when you hold back the mower on turns. So you have to slow it down with partial engagement.

Nancy Golden
User Rank
Platinum
Re: Planned Obsolescence
Nancy Golden   5/21/2012 10:19:16 AM
I think there has been a definite shift in corporate strategies and planned obsolescence is a part of that shift. I recall products lasting 10-15 years that have a 1-2 year life today. Our kids are being brought up in a disposable society and regard this as normal, but having grown up in the previous generation where quality and customer service were king, I often struggle with the new corporate culture.

Tool_maker
User Rank
Platinum
Re: Planned Obsolescence
Tool_maker   5/30/2012 1:07:29 PM
NO RATINGS
Excuse me if I rant a bit. It is not so much a corporate shift as a response to the reality of today's consumer spending habits. If Sears sold the quality of lawn mower that you recall lasting 10-15 years, most people would go down to Walmart and get another model that is $50 bucks less and then lament the fact that it does not last.

We consumers have repeatedly demonstrated our willingness to accept junk, so long as it does the job for awhile and costs less. I just replaced our refrigerator after our old Whirlpool died after 25 years. The salesman laughed when he said we expect 10 years today and I do not have one in the store built like your old one. I do not know the veracity of that statement, but I do know our basement refrigerator was built in the early 50's and is still making things cold. It is ugly, probably inefficient, needs to be defrosted, and only makes ice if you fill the tray, but it works.

As long as we demand more toys and are willing to accept more junk to save a buck or two, why are we surprised when retailers feed that clientel. Quality is not dying so much as we are killing it. I have worked at companies that produced products which ended up as parts in Craftsman tools. Radial Arm Saws are one I am most familiar with, and Sears was a demanding customer, but they charged a premium price. Harbor Frieght and their third world imports changed the rules for the home hobbyist that was Sears' primary customer.

I hate to see how quality has gone by the wayside, but I am not always sure it was not a consumer driven trip.

Nancy Golden
User Rank
Platinum
Re: Planned Obsolescence
Nancy Golden   5/30/2012 1:26:36 PM
NO RATINGS
I absolutely see your point Tool_maker, but I am still not sure if it is consumer driven or manufacturer/distributor driven. I have a friend that works for a company that consistently does business with China. He tells me that their Chinese manufacturers can make high quality products - but it is driven by what their customer (i.e. American distributor) is willing to pay. In a competitive market society like ours, it could be financial suicide to opt for the higher priced higher quality part when their competitors are underselling them with a lower quality part. The consumer is not always given a lot of choice because the decision is made by the distributor to remain competitive. I personal would pay the $50 extra for a product that would last, but those products are hard to find. A warranty is typically offered (for $50) instead that has so many loopholes in it that it is really worthless.

Rob Spiegel
User Rank
Blogger
Re: Planned Obsolescence
Rob Spiegel   5/30/2012 1:34:17 PM
NO RATINGS
Really good point, Nancy. It could be that what we're seeing with faulty manufacturing from China may be a reflection of what U.S. manufacturers are willing to pay for rather than the intrinsic quality of the goods made in China.

Nancy Golden
User Rank
Platinum
Re: Planned Obsolescence
Nancy Golden   5/30/2012 1:58:43 PM
NO RATINGS
Another thing that drives that Rob, is the minimum quantities often required by Chinese manufacturers. That almost forces some American distributors to have to go with a cheaper price=cheaper product to be able to afford the MOQ required by the manufacturer. I have a small business and buying from China is not even an option for me because there is no way I could meet their minimum order size. My products are made in the U.S.A. and are of high quality materials that will last, but the price I have to sell them for certainly reflects that and I probably don't see near as many sales as I would if I was able to drive the cost down. However, I am committed to quality so while I have a poor profit margin, my integrity remains intact LOL

Rob Spiegel
User Rank
Blogger
Re: Planned Obsolescence
Rob Spiegel   5/31/2012 12:52:32 PM
NO RATINGS
From what you're saying, Nancy, it sounds like you could turn to China production if you were willing to produce a cheaper product. That may be the clue to problems with China-produced products -- a move to lower quality in order to reach high quantities and meet the inexpensive threshold.

Nancy Golden
User Rank
Platinum
Re: Planned Obsolescence
Nancy Golden   5/31/2012 1:18:32 PM
NO RATINGS
I believe that is correct Rob, part of the fall out of our global economy. It certainly is a mixed blessing...

Rob Spiegel
User Rank
Blogger
Re: Planned Obsolescence
Rob Spiegel   5/31/2012 2:27:51 PM
NO RATINGS
You certainly offered a new twist on China manufacturing. I always viewed China as a manufacturing option for high-quantity/low-mix products. Apparently, the low-cost opportunities are prompting some brand owners to redesign their products to become low-mix items.

Nancy Golden
User Rank
Platinum
Re: Planned Obsolescence
Nancy Golden   5/31/2012 3:05:26 PM
NO RATINGS
That's right, Rob. I just got back from lunch with my friend who works for the American distributing company that buys from China that I mentioned earlier. He said that you can specify any part you want - if it is electronics based and you want the components to come from a certain manufacturer, they do it for the agreed upon price and it goes through QC to ensure that happens. Same thing with any other critical component - the buyer can specify its source as long as they are willing to pay for it. It all comes down to cost: if the distributer insists that the manufacturer shave off 10% of the price before they will buy - it isn't the manufacturer's profit margin that will necessarily suffer - it may very well be the quality of the parts...

Rob Spiegel
User Rank
Blogger
Re: Planned Obsolescence
Rob Spiegel   5/31/2012 3:27:24 PM
NO RATINGS
Yes, I can see how that works. Nancy. That certainly explains why some of the products coming from China have problems. 

Tool_maker
User Rank
Platinum
Re: Planned Obsolescence
Tool_maker   6/1/2012 8:18:42 AM
NO RATINGS
You would be willing to pay the extra $50, but too many end users will not. Therefore, your friends experience in China backs my point. The distributer will buy what he can sell, regardless of price. But why would he buy the highest quality to only see it sit, unsold in a warehouse somewhere. Consumers are the driving force and so long as we demand cheap and are willing to accept junk no retailer is going to survive trying to sell only high quality expensive merchandise except in rare niche markets.

There will always be people willing to spend $100 for an Armani shirt just so they can say they are wearing Armani. But the vast majority of us cannot and will not do that. So Arrow shirts are now made in, take your pick of third world countries, so it can sell at local department stores for $25 instead of the $35 it would cost to be made in the US. That pattern has repeated so many times that it is not arguable. So when we are griping and moaning about poor workmanship and low quality we need to look in the mirror and honestly ask what we are willing to pay for now and what did we accept in the past.

We need to turn the ship around, but in many cases it is too late. True enough there are/were many short sighted CEO's who off shored entire product lines and since have allowed factories to become obsolete before they were closed never to return. But it never would have happened if we as consumers had not facilitated the change. Go into any modern machine shop and count the number of new US made mills, lathes, grinders, etc. They no longer exist. Corporate America mirrors the population, it does not dictate the terms. Middle class America is not being murdered, it is committing suicide. End of rant.

Rob Spiegel
User Rank
Blogger
Re: Planned Obsolescence
Rob Spiegel   6/4/2012 3:19:06 PM
NO RATINGS
You're right about the pricing problem, Tool_maker. A good example is the way WalMart would come to a small town and wipe out mom-and-pop stationary stores, gardening stores, hardware stores. That would happen even though the small stores were owned by neighbors.

Tim
User Rank
Platinum
Re: Planned Obsolescence
Tim   5/21/2012 9:01:38 PM
The Sears motto for a long time was "We service what we sell."  This is great to have a service department, but it would also be great to not need service.

Jaybird2005
User Rank
Silver
Re: Planned Obsolescence
Jaybird2005   5/22/2012 9:40:21 AM
It does look like 'planned obsolescence', but it might also have been a safety device. If the mower gets up against something solid, like a tree, and the operator (possibly inexperienced) does not release the handle a metal-to-metal gear system may cause damage to the metal gears or cause the mower to bend it's deck or jump in an unexpected way. The existing system would simply strip the plastic gears. It may be better to have the mower stop moving than to risk some other, more severe, damage.

 There may have been problems with stones or tree bark getting between the gears and causing severe damage (if they were metal) where the plastic might flex and allow the stones to be ejected with some minor damage to the plastic part rather than a gear grinding halt to the entire system.

williamlweaver
User Rank
Platinum
Re: Planned Obsolescence
williamlweaver   5/22/2012 9:46:18 AM
NO RATINGS
@Jaybird2005 I'm always extending the benefit of the doubt to manufacturers, having had to make some tough choices and comprimizes of my own when it comes to development. I didn't own the specific lawn mower in this story, but I would have hoped that if the design was for safety that advertising would have touted it as a positive, advertised this safety "feature", and then provided a spare polymer gear or two with purchase and stocked them in the department store at just over cost... 

Contrarian
User Rank
Gold
Re: Planned Obsolescence
Contrarian   5/22/2012 9:52:51 AM
NO RATINGS

ionceownedafrontwheeldrivemowerandratherthanchewupthegearsandgetalurcheverytimeengagingthedrive,thetechniqueiusedwastopushdownonthehandleandengagethedrivewiththefrontwheelsintheair. themowerwon'tlurchthatway,itextendsthelifeofthedrivelineandyousimplycontroltheforwardmotionbypushingdownonthehandlemoreorlessgivingthedrivewheelsmoreorlesstraction. ineverhadadrivelineissuewiththemowerforthe10yearsorsoiownedit.

armorris
User Rank
Platinum
Re: Planned Obsolescence
armorris   5/22/2012 10:13:46 AM
NO RATINGS
The drive system needs some kind of a slip clutch. The teeth become disengaged well before the drive belt is sufficiently loose to disconnect the engine power. This is how the wheel teeth get chewed up.

jeffbiss
User Rank
Gold
Just poor design for higher initial profit
jeffbiss   5/22/2012 10:27:05 AM
NO RATINGS
I have a Sears reciprocating saw that failed because the drive shaft wore excessivley because the guide was not a traditional bushing, it is an iron casting, AND the manual provided absolutely no information about having to open the case and oil it (there is no oil port, so I didn't even think about it, so I'm partly to blame). And you can't get any replacement parts for any tool more than a couple of years old, I've had to make my own parts.

So, one had better take a good look at a machine before buying as the manufacturer may have been more concerned with their initial profit than the customer's long term satisfaction. And, there may be the calculation done, like Ford did, that dissatisfaction, or death, is a cost that they are willing to bear if failure is below a certain level.

OLD_CURMUDGEON
User Rank
Platinum
Re: Planned Obsolescence
OLD_CURMUDGEON   5/22/2012 12:20:12 PM
1)  Seems to me that there should have been a two-stage linkage for the motion drive mechanism.  The one stage would force the proper engagement of the driving gears into the wheel gears, and the "feathering" for motion control should have been accomplished w/ the "pressure that the drive belt exerted on the driving shaft sheave.  Ultimately, the V-belt would have been the sacrificial element in this drive, and since V-belts are considered consumer items & consumables, they're available at a wide range of outlets including automotive stores, etc.

2)  Regarding the SEARS / K-MART alliance.  I believe that was one of the worst corporate marriages to come down the pike in many a decade.  In this Tampa Bay area, and more specifically in our immediate hometown area, we have FOUR WAL*MART outlets, within bicycling distance, and ONE SAM'S CLUB.  We also have TWO K-MART stores & ONE SEARS store.  Driving past these outlets is very revealing, and is NOT tied to time of day OR day of week.  The K-MART parking lots have a handful of vehicles parked, while the WAL*MART stores show almost full parking lots (and I'm NOT just relating at Christmas time!).  The Sears store is a general merchandise store, including an automotive service center.  Interestingly, it is located at the end of a very large mall, also populated w/ BEST BUY, DILLARDS, J.C. PENNEY, MACY*S (formerly Burdines), etc.  The parking lot area in front of the Sears store is very modestly populated.  I believe Sears would have been far better off to remain independent, while at the same time trimming their product lines to include only their "core" businesses, which are tools, appliances, & automotive accessories & light repair.

Rob Spiegel
User Rank
Blogger
Re: Planned Obsolescence
Rob Spiegel   5/22/2012 2:29:13 PM
NO RATINGS
I have to agree with you about the Sears / Kmart match-up, Old Curmudgeon. What you described about the parking lots is very much true where I live. I did some very late Christmas shopping mid-day on Christmas Eve at Kmart and the store wasn't even crowded. The lines at the check-out were one or two people deep.

Charles Murray
User Rank
Blogger
Re: Planned Obsolescence
Charles Murray   5/22/2012 8:21:27 PM
NO RATINGS
I think what it comes down to, Old Curmudgeon, is a corporate culture that values short-term savings. In the long run, no serious executive can argue that poor quality makes the company stronger. But cutting corners makes them look like heroes -- for a short time, anyway. Sparsely-populated parking lots certainly aren't their goal, but the geniuses who place value on the short term fix usually aren't around to see the results of their decisions.

TJ McDermott
User Rank
Blogger
Re: Planned Obsolescence
TJ McDermott   5/23/2012 3:02:57 AM
NO RATINGS
Metal on polymer is often a very good choice under certain load conditions.  With the right polymer, the interface requires no lubrication.  Polymer geared wheels are very easy to manufacture.

"Planned obsolescence" is the unsavory name for simple design compromise.

This lawn mower could have been designed with case-hardened steel gears and a built in auto-lubrication system for them, but then no one would purchase this extremely expensive lawn mower.

As stated in other comments, the weak "link" was the wheels, but the actual flaw in the design lay elsewhere.

warren@fourward.com
User Rank
Platinum
Re: Planned Obsolescence
warren@fourward.com   5/24/2012 5:53:11 AM
NO RATINGS
Actually, I don't think is was the plastic on metal that was the problem.  I think it was the partial merging of the gears that created the mess.  Now it makes me worry about how my lawn mower works.  I happen to like the auto-pulling feature.  For the first time in years I have a lawn to mow, and I appreciate all the help I can get!

Rob Spiegel
User Rank
Blogger
Re: Planned Obsolescence
Rob Spiegel   5/24/2012 2:25:28 PM
NO RATINGS
I agree Warren. The partial engagement is a poor way to modulate speed, even if it's metal to metal. That fact that it was metal to plastic just meant the plastic gave out first. A different system to modulating speed is the real design solution.

connieM
User Rank
Iron
Re: Planned Obsolescence
connieM   6/16/2014 3:50:44 AM
NO RATINGS
Planned obsolescence has existed for a long time in different ways. It is one of the strategies of manufacturers to make more money. The sad thing is, not everyone knows what it is all about. Nowadays, every product is made with the knowledge and intention of being obsolete within a few years. Here is the article: Planned Obsolescence.

ChasChas
User Rank
Platinum
linkage problem
ChasChas   5/22/2012 9:50:44 AM
NO RATINGS
 

I'm okay with the plastic gear on the wheel - quiet meshing and durable.

The gears need to mesh before the power comes - a linkage problem.

Also, a spring is needed to allow for when the teeth are out of rotation for meshing before the power comes on - snaps in when the power starts.

I see a poor linkage design or it is out of adjustment. 

OldGeek
User Rank
Iron
Re: linkage problem
OldGeek   5/22/2012 12:57:22 PM
NO RATINGS
Dead on the money ChasChas! The gears should engage fully before the belt tightens, thus always being fully meshed before any power is applied.

The gear disengagement is necessary to allow the mower to be pushed manually.

With regard to other posts about controlling speed: I've always controlled the speed by applying downward pressure on the handle to allow the front wheels to slip. That's why they put power to the FRONT wheels!

 

BRedmond
User Rank
Silver
Self-Propelled Mower Plastic Drive Wheels
BRedmond   5/22/2012 10:56:14 AM
NO RATINGS
I've had the same problem with mowers sold by Home Depot and Toro.  The HD one had teeth on the inside of the "back" side of the rim.  The Toro I'm currently using has a gear molded into the back side of the hub.  The Toro is supposed to adjust its speed to match your walking pace.  I've never done a teardown to figure out how it is doing that.

My dad had a mower when I was a teenager where a knurled or toothed wheel engaged the tread of two tires (front or rear, I can't remember).  Pretty sure that the system was adjustable but eventually you need new tires because, again, the drive was more durable than the driven wheels.

Some of the comments seem to be talking about tractors or more industrial types of mowers.  I read this as a typical residential, walk-behind mower with self-propulsion.  Most of these don't have real speed adjustments (other than the Toro).

MaruaderMan
User Rank
Iron
Even GM got in on the act years ago....
MaruaderMan   5/22/2012 11:15:47 AM
While General Motors wasn't the first to apply plastic to a gearing system, they sure made a bundle out of it.  From about 1968 to 1976, Pontiac introduced their plastic coated cam timing chain gear.  Ostensibly, it was to "quiet down" the noise the two cam timing gears and chain made during normal engine operation.  Of course, the difference in noise could be measured in practically negative decibels.

Normal timing gear/chain lifetime used to typically exceed 100k miles - even in those days.  With the plastic coated gear, one never exceed 65k miles - if you were that lucky. and it always happened on the road and required a tow.  At least at 100k miles, you knew from experience what to expect, and premature timing gear failure was not one of them.

The replacement, whether from GM or aftermarket, was always all steel.  Gee!

Planned obsolescence?  Even back then the accountants and management were already working their magic.

By the time the NTSC got involved, it was too late.  GM had already changed back to the all-steel gears, and the gov't chose not to pursue the problem any more.

Jeff Martin
User Rank
Silver
A little more info.
Jeff Martin   5/22/2012 12:33:50 PM
NO RATINGS

I have a Toro with the variable walking speed drive.   I too have not looked at how it works, but I understand that these wheels will have to be replaced from time to time when they start slipping.  I was made aware of that fact after I bought the mower by a friend that used to work for the city and had to replace them all the time.  My drive skips on steep parts of my yard and makes a nasty sounding cogging noise.   I have not tried fixing it yet, but I am hopping they use the same wheels in the front as they do in the back.   So when my gears or cogs become worn I can just "rotate" the tires.

 

This place in MN has some pretty good prices...I just checked my price $19 per wheel!!!

 

http://www.psep.biz/

 

 

Here is a GREAT manual on Toro transmissions. 

 

http://www.amopower.com/Toro%20Lawn-Boy%20Walk%20Behind%20Power%20Mower%20Drive%20Systems%20Manual.pdf.

 

There they list the benefits of the engaging pinion drive.

 

The wheel pinion clutch has a three-fold purpose. One,

when the transmission is engaged, it causes the pinions

to move with the output shaft and drives the wheels.

Two, it provides differential action to allow easy turning

and excellent maneuverability. Three it disengages the

wheel pinions from the output shaft when the operator

is not squeezing the handle. This allows the wheels

to turn backwards without turning the gears inside the

transmission and provides low pull back forces similar to

those on a hand-push version (Fig. 136).

 

armorris
User Rank
Platinum
Re: A little more info.
armorris   5/22/2012 3:27:30 PM
NO RATINGS
 

My (Sears) mower does not have a differential drive like in a car. When one wheel slips, the other wheel still pulls. IMO, a differential drive would not be a good idea on a mower where the terrain is uneven.

armorris
User Rank
Platinum
Re: A little more info.
armorris   5/22/2012 3:38:27 PM
NO RATINGS
Thanks to Jeff Martin for the link to the great mower transmission manual. Nice educational material, even though my mower is not much like the ones described in it.

Jeff Martin
User Rank
Silver
Differentials, front wheel drive, and ratcheting oneway clutches.
Jeff Martin   5/22/2012 4:25:36 PM
NO RATINGS

According to the manual I mentioned earlier I have a Toro 20031 with a 22" steel deck, a single speed bevel gear system (new in 2002)  a second generation Personal Pace drive system, and spring racket wheel pinions (Fig 112 page 3-26)

 

Front wheel drive mowers should have a non-differential direct drive.   You do not need it because you lift the front wheels when you turn the mower.   The problem with these mowers is that the wheels slip in the grass when mowing up steep hills.  I remember as a kid having to lift the rear of the mower off the ground to get enough weight on the front wheel to give it traction to power up an embankment.   Remember Fictional Force = Us x Cos(angle) x weight.   Rear wheel drive naturally applies that pressure to move up hills and you don't have to do that awkward rear lift.

 

My rear wheel drive mower it needs a differential for me to turn.   But it also needs a direct drive so I have 2 wheel traction and don't become a spinning one wheel wonder.   So does it have a possi traction system?  Well yes it does.....in a way.    It uses a cleaver racketing pinion gear.   The pinion key is spring loaded in the shaft and the pinion keyway is flat on one side and ramped on the other.   So it will racket forward but not backward.   Cool design.    So most of the problems with my wheels slipping is not from engaging gears (because mine are always engaged) .   The problem is caused by my deck and adjustable wheel height mechanism is that it is compliant.  It is sheet metal and not perfectly rigid so it will bend slightly and the pinion gear will slip.   The cool thing is my variable speed is controlled by belt slip.   It only requires one hand ...and even one finger to push my mower forward.   That pushing on the handle is transferred to the bevel gear housing and it will pivot the pulley loosing and tightening the belt.   The speed is variable up to 4.8 mph. I don't like the slipping belt slipping in the design because I thought it would wear out fast, but I have not had to replace it in since I bought the mower in 2004.

LloydP
User Rank
Gold
Plastic on metal gears
LloydP   5/22/2012 10:25:48 PM
NO RATINGS
This is not uncommon. Most garage door openers use a steel worm gear on the motor shaft, mated to a plastic gear driving the lift mechanism. Guess what is the most common failure of the opener?

For years, GM used a power headlight lift motor on Firebirds, Corvettes, and the Fiero. The motor was a modified power seat motor with a steel worm gear. It mated to a plastic gear on the lift mechanism. The motor drive electronics sensed motor current, and shut off when the current increased after the lift mechanism drove hard against a stop. When you see a "one-eyed" Firebird or Fiero, you know the plastic gear has stripped. Most Corvette owners fixed this problem with a new lift motor. It had to be new, as the gears in junkyard parts also were stripped.

William K.
User Rank
Platinum
metal trumps plastic in mower
William K.   5/23/2012 8:31:47 AM
NO RATINGS
I have used both self propelled and non self propelled mowers and I find that it takes far less effort to mow a lawn without the alleged work saving feature. At least that is when the lawns are a bit smaller and have anything other than wide open spaces. Constantly turning and pulling the mower back is a lot more work if I must be dragging the heavy drive mechanism as well as the mower weight. 

And of course the mowers are mostly designed to only last a year or two, so as to sell more mowers. So what comes across as a design goof may actually be intended to make the machine last only a bit beyond the warranty period. Simpler is often better.

bobjengr
User Rank
Platinum
MOWER
bobjengr   5/23/2012 4:21:38 PM
NO RATINGS

Several years ago several neighbors and I took turns cutting the grass for a gentleman who had a stroke.  He was in the process of recovery but certainly in no condition to continue with his ward work.     The lawn was quite small so he had a push mower and never bothered to purchase a motorized self-propelled device.   One of those rotary types that are no longer made.  Although very skeptical at first, I started the process and was amazed to find out how much quicker I completed the job and what a "better cut" I got from the old, but very sharp, blades.  For this job, the more simple process was the best process.

Cadman-LT
User Rank
Platinum
Built to fail
Cadman-LT   5/31/2012 8:56:38 AM
NO RATINGS
That design, with those materials is built to fail no question. 

Remee_S
User Rank
Iron
Planned Obsolescence
Remee_S   9/1/2012 1:33:10 AM
NO RATINGS
We are so used to the disposable, throaway society. Most stuffs today don't last more than two years, or should I say a year. Ever make an effort to get a part for some product in the household, like a fridge or washer only to find the part is not made anymore? It's known as planned obsolescence, something producers plan for to keep individuals getting more stuff. The only way to really beat planned obsolescence is to buy things as cheaply as possible. That way, at least you aren't getting ripped off as much.

AREV
User Rank
Gold
Re: Planned Obsolescence
AREV   3/12/2013 6:03:39 PM
NO RATINGS
We buy cheap so we can buy more. The Mower was a Sears not a Walmart. Sears used to supply quality stuff - Craftsman. They nearly went under and now owned by KMart - always the quality store. The adage "You get what you pay for"  in my experiance is you get less for your money when you save a buck. Where I work there is a sign that states " the price is forgotten long before the product wears out". We've never gone lacking for customers. Second - If the operator is letting the mower drag them over the yard nothing will hold up. I never liked self propelled because thay added wight to the mower and they never went the correct speed. Get some exercise and push  that lawn.



Partner Zone
Latest Analysis
Enabling the Future is designing prosthetic appendages modeled more like superhero arms and hands than your average static artificial limbs. And they’re doing it through a website and grassroots movement inspired by two men’s design and creation in 2012 of a metal prosthetic for a child in South Africa.
In order to keep an enterprise truly safe from hackers, cyber security has to go all the way down to the device level. Icon Labs is making the point that security has to be built into device components.
Senior Technical Editor Chuck Murray gets the skinny on Harting Inc.'s 3D MID technology, which allows users to create a three-dimensional circuit board out of molded plastic.
Three days after NASA's MAVEN probe reached Mars, India's Mangalyaan probe went into orbit around the red planet. India's first interplanetary mission, and the first successful Mars probe launched by an Asian nation, has a total project cost of nearly $600 million less than MAVEN's.
Siemens PLM Software has made an in-kind donation of software to Central Piedmont Community College in North Carolina for its science, technology, engineering, and mathematics (STEM) Division.
More:Blogs|News
Design News Webinar Series
9/25/2014 11:00 a.m. California / 2:00 p.m. New York
9/10/2014 11:00 a.m. California / 2:00 p.m. New York
7/23/2014 11:00 a.m. California / 2:00 p.m. New York
7/17/2014 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Oct 20 - 24, How to Design & Build an Embedded Web Server: An Embedded TCP/IP Tutorial
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Next Class: October 1 - 30
Sponsored by Gates Corporation
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service