One of the two front wheels that propel my Sears Craftsman self-powered rotary lawnmower stopped working, while the other wheel started working intermittently. When I removed the plastic cover over the drive mechanism, I saw what appears to be a worm-drive transmission that was coupling power from the engine via a belt to a shaft driving the two front wheels.
While squeezing the control bar on the handle, I could see the drive shaft turning, but one of the wheels was not turning. Once I removed the front wheels, I noticed that at least half of the teeth had been almost ground away inside of one wheel, while a smaller section of the teeth had been ground away in the other wheel.
When the drive control bar on the handle is squeezed, the worm-drive transmission is pivoted forward, presumably on a bracket attached to the deck. When that happens, the pulley tightens up against the belt, drawing power from the engine. As the transmission pivots, the drive shaft is moved forward, engaging the gears on the ends of the drive shaft into the teeth inside the front wheels. The front wheels are made of plastic with gear teeth molded inside the rim.
The gears on the ends of the drive shaft are made of metal and are engaged into these plastic teeth when the mower’s self-propulsion system is engaged. If the operator doesn’t fully squeeze the control bar up against the handle bar, the metal drive gears are not fully engaged and literally chew away the plastic teeth inside the front wheels. Replacing the wheels is only a temporary fix, as the new wheels will suffer a similar fate.
This entry was submitted by Andy Morris and edited by Rob Spiegel.
Tell us your experiences with Monkey-designed products. Send stories to Rob Spiegel for Made by Monkeys.
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.
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?
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.
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.
*** 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...
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