Multiple Speeds, Commercial Laundry. Programming
MILNOR commercial washer/extractors today, use a single motor and an inverter to achieve multiple and variable speeds.
Before inverters, Larger Milnors (above 50 lb capacity) used a seperate motor for each speed, tied together with a helical drive gear box. A standard machine would come with 3 motors, a wash motor, a distribution (drain speed) motor and an extract motor. A 4th motor could be added at an extra cost for a low speed extract.
Milnor always used continuous duty, single speed motors so that the machine could perform as many intermediate extracts as desired. 2 speed motors used on other commercial machines would overheat and limit there ability to perform multiple intermediate extract steps and thus these machines would normally be set up to perform only a final extract which then needed to be set up for more rinse baths.
For for over 35 years, Small Milnor washer extractors (35, 50 and 55lb capacities)used a complex yet very reliable system to achieve 4 speeds. These machines did then, as they do now, have a 30" diameter cylinder.
2 single speed Motors - we'll call the wash motor and the extract motor. And 2 12 volt friction clutches, we'll call the wash cluch and the extract clutch....tied together by a "jackshaft" to drive the cylinder.
It worked like this;
wash speed(about 35-37 rpm)= wash motor engaged, wash clutch engaged,extract motor not engaged, extract clutch not engaged
distribution, drain speed(about 65-70 rpm)Wash motor not engaged, wash clutch engaged, extract clutch not engaged, extract motor engaged
low speed extract(about 350-450 rpm depending upon model)wash motor engaged, wash clutch not engaged, extract clutch engaged, extract motor not engaged.
High speed extract(about 400 to 600 rpm depending upon model)wash motor not engaged, wash clutch not engaged, extract motor engaged, extract clutch engaged.
In otherwords, the wash motor ran the wash speed and the low extract speed. The extract motor ran the drain speed and the high extract speed, through 2 clutches.
FYI a 30" diameter cylinder spinning at 600 rpm produces 153 G's
Before microprocessors, these machines where timer driven. To tie all of the above together, a system of contactors and timed relays were used to see the machine through it's steps "automatically"....so that sales reps and chemical reps. did not have to be rocket scientists to set the machine up for actually processing laundry.
In a coin op laundry situation, the timer cam was set at the factory and no one had to worry about anything. The machine, when started would follow it's timed sequence of events and wash clothes.
In an OPL(On Premise Laundry) situation or at a commercial laundry the chemical or soap supplier had to programme the washer's cycles or formulas. Programming was done not with a keypad, but a black magic marker, pocket knife and indicator stickers. You actually created your own timer cam chart, telling the machine what to do and when to do it. Fingers, touching the copper cam would execute a command. Each finger controled a function of the machine. When you cut a slot on the chart so that the finger would touch the copper...that fingers function would be executed.
For a chemical supplier to understand all this, the key was to understanding the drain finger on the cam chart. These machines are all gravity drained, with a normally "open" drain...meaning the drain is open unless the drain finger on the cam chart was touching the copper and there was electricity present. So, during a Fill, a Flush, a Wash, a rinse.....any bath...the drain finger is touching the copper keeping the drain shut so the water says in the machine.
So now it's drain time on a MILNOR and we get back to the discussion about relays.
The programmer, with his pocket knife...cuts a slot on the plastic cam chart to wash in suds for 10 minutes. Other fingers are touching the copper at this time. The water temp, what chemicals to inject and so forth...but the drain finger is touching the copper for the 10 minute wash, keeping the drain closed. During the 10 minute wash, a reversing contactor is telling the cylinder to wash ccw for 20 secs, dwell for 3 and reverse for 20 secs.
10 minutes expires and the drain finger leaves the chart...is no longer touching the copper.
At this point 1 of 2 7.5 second relays go into action. The drain finger leaves the chart and reguardless of the current rotation of the cylinder, the first 7.5 second relay starts timing out. For 7.5 seconds the cylinder is forced to rotate at wash speed clock wise(wash motor and wash clutch engaged) for 7.5 seconds.
When the first 7.5 second relay times out a second 7.5 second relay takes over. This relay causes the machine to accelerate into drain speed(wash clutch engaged, extract motor engaged) NOTE...THE DRAIN VALVE IS STILL SHUT AND WATER IS IS STILL IN THE CYLINDER, The timer has been halted for a total of 15 seconds.
Even tho the drain finger left the cam chart 15 seconds ago, the drain is still shut because of the 2 relays, letting the washer/extractor wash cw for 7.5 seconds and then distribute for 7.5 seconds prior to dumping the water. When the second 7.5 second relay times out, the drain valve opens and lets the water out for the alotted time that the programmer(cam chart cutter has alotted. Usually 60 seconds.
