Maytag’s Dependable Drive
Transmission redesign began nine years ago as a low-priority project. Today it’s a star. When one of Maytag’s research and development engineers stepped forward in early 1981 with an idea for simplifying the transmission in Maytag washers, the concept was put on the back burner.
Eventually, however, the idea resulted in Maytag’s Dependable Drive (TM) transmission, introduced last fall.
Maytag is so pleased with this redesign effort, it extended the transmission’s warranty from five years to 10 years. In the beginning …
So why was Maytag slow in moving forward with the redesign?
“In 1981, it was a matter of priorities,” says John Mellinger, vice president of research and development. “We were involved with developing our stacked washer and dryer.
“Plus we had a transmission out there for a lot of years (35 to be exact) that was doing an awfully good job. So we let the 1981 concept coast as a low-priority project, even though the concept showed a lot of potential.”
The concept called for converting the rotary motion of a single gear (the previous design had three gears) to the back-and-forth rocking of the agitator.
One of my engineers came to me with an 8-in.-high, 4-in.-wide, handmade wooden mockup, ” says Mellinger.
A working model was soon developed to prove the legitimacy of the principle.
But it wasn’t until 1983 that Maytag’s research and development engineers began working with the company’s manufacturing engineers on design evaluation. This work continued through 1984.
“As soon as we are seriously considering a design concept,” says Mellinger, “manufacturing engineering is in on the evaluation because they also have to speak to reliability and productibility issues before we go into production.” Black art
During the evaluation process it became evident that if the transmission redesign was to be successful, Maytag engineers would have to rethink another key component-the agitator.
The new agitator moves to and fro at 153 strokes a minute, as compared to the 64 strokes of the previous design. More strokes means there’s a greater chance that clothes may snag and tear, so the agitator was designed to be much smaller.
“We started out with a lot of agitator designs,” says Mellinger. “This is very much a black art. There aren’t exactly any textbooks on the subject. We spent a lot of time designing an agitator that would wash clothes very well without requiring more power so it could be used on all Maytag washers produced since 1956.” Task force formed
in early 1985, a multifunctional task force was formed to review the transmission for efficient manufacturability and reliability.
The group consisted of 12 persons representing research and development, manufacturing, design, marketing and finance, says Bob Faust, vice president of manufacturing.
“The transmission is the key element of our washing machine so we approached the redesign very cautiously,” says Faust.
Throughout the investigation phase, Maytag conducted extensive life tests on machines that house the new transmission.
“We were washing the equivalent of 10-lb. loads and were looking to accomplish a 10,000-machine cycle life (approximately 1,800 hours), the equivalent of a 20-year life,” says Faust.
While Faust and his manufacturing engineering group were conducting their tests, marketing was also evaluating product performance.
We manufacturing engineering) were looking at reliability of components,” says Faust. “Marketing was evaluating washability.”
Marketing was also concerned over the possibility of a negative reaction from our dealer network, says Mellinger.
“They (marketing) have their own product evaluation laboratory and spent much time evaluating whether a new agitator stroke and speed might scare away our retail customers.”
Meanwhile, Mellinger’s research and development group was busy investigating and evaluating materials, tooling and serviceability.
“We really took a good look at both reliability and washability,” says Mellinger.
One of the more important benefits we realized early on was that the entire transmission could be serviced from the front of the machine without removing the transmission.”
The redesign allowed all parts to be lifted out of the transmission by removing the front panel and transmission cover plate.
“Most gearcases require you to start at the top of the washer by taking off the tub and spinner, and working your way down before you can get the transmission in your hands to service it. This simplicity of service is one of the things we were quite enamored with early on,” says Mellinger Greatest DFM effort yet
When we formed the task force, we got very involved in design for manufacturing,” turing,” says Mellinger.
We evaluated die-cast gears, plastic gears, plastic components, castings. We evaluated a variety of different ways of manufacturing the few parts (40 as compared with 65 in the previous design) in the gearcase at the lowest cost possible without sacrificing quality.
“This project represents our greatest DFM cooperative effort between manufacturing and research and development in anything we’ve ever done. “