|
Post by Travis on Oct 27, 2018 15:18:02 GMT
Very cool. I find it fascinating that you tackle projects that no one else seems to. I've always avoided belt-drive models because they seemed hopeless.
I only picked that one up because of your prodding and the condition. I am mourning the loss of the older motor as that's my favorite. The 2 dr that the scrappers stole had that motor.
|
|
|
Post by coldspaces on Oct 27, 2018 15:30:55 GMT
Great work!
|
|
|
Post by turbokinetic on Oct 27, 2018 15:38:48 GMT
Very cool. I find it fascinating that you tackle projects that no one else seems to. I've always avoided belt-drive models because they seemed hopeless. I only picked that one up because of your prodding and the condition. I am mourning the loss of the older motor as that's my favorite. The 2 dr that the scrappers stole had that motor. Thanks! I enjoy a challenge because it keeps the mind sharp! In reality, nothing has been difficult to actually do. The only thing really tedious wrong with this has been the shaft seal. The rest of it's just nuts and bolts.
You got to remember that even when these were current models, they required routine maintenance. Frigidaire had a field service group, just like we have today for large stationary equipment. These units always leaked to some degree and required maintenance that hermetic units don't require. For that reason, finding an all-original unit which still has its charge and works, is just not going to happen. But hopeless is an awful strong word.....
I'm still also feeling bad about the motor. They used such poor materials due to not knowing better at that time. I'm hopeful that a repair process can be developed to install new weights. For now, it's safely boxed up for the future. On a positive note; the motor we're using is larger and will be able to support a higher compressor RPM. That will help prevent "jerking" of the belt and the associated noises. It will also allow for lower duty-cycle.
Thanks Gill!
|
|
|
Post by birkie on Oct 27, 2018 16:09:29 GMT
It seems that the old oils in use at this time were not thermally stable; and especially not when mixed with SO2. The heat of compression would coke up the oil into the mess you see. Ah, yes. It was a known problem at the time. Given enough time and/or heat, an SO2 environment will reduce the oil to elemental carbon. There was some contemporary (to the 1930s) literature posted here a few years ago that suggests the makeup of the oil (aromatic rings vs branched chains vs straight) made a big difference in how resistant an oil was to degradation with SO2 under heat. Oil was specially refined for this purpose, and they we're constantly learning/improving. Big improvements we're made between the mid 20s and the mid 30s. The big companies bought the batches that tested best, but none of it was perfect.
|
|
|
Post by turbokinetic on Oct 27, 2018 16:24:36 GMT
It seems that the old oils in use at this time were not thermally stable; and especially not when mixed with SO2. The heat of compression would coke up the oil into the mess you see. Ah, yes. It was a known problem at the time. Given enough time and/or heat, an SO2 environment will reduce the oil to elemental carbon. There was some contemporary (to the 1930s) literature posted here a few years ago that suggests the makeup of the oil (aromatic rings vs branched chains vs straight) made a big difference in how resistant an oil was to degradation with SO2 under heat. Oil was specially refined for this purpose, and they we're constantly learning/improving. Big improvements we're made between the mid 20s and the mid 30s. The big companies bought the batches that tested best, but none of it was perfect. Ah yeah I remember reading about this as well. It seems that SO2 is just Does Not Play Nice With Others. It's an angry spiteful demon always looking for something to react with. Things like motor windings, oil, moisture + metals, terminal seals, and service technicians are fair game for reacting with.
This compressor is in and of its self a neat design. There are some high performance design elements in it which make it impressive even by today's standards. The way in which it's ported on the intake side would allow it to remain volumetrically efficient even at high RPM's and very low suction pressures.
It's apparent that they were concerned about changing from a 2 cylinder to a 1 cylinder compressor and making sure it didn't cause them to have a low capacity system!
|
|
|
Post by turbokinetic on Oct 28, 2018 4:05:51 GMT
Today I was able to get the compressor re-sealed and back together. Amazingly, all the parts were still usable. I was pleasantly surprised when the shaft was not as deeply pitted as I had feared. After making a few cleanup passes with the lathe, it was still acceptable size for the seal. That was great news!
The valve plate got sonicated in Zep Industrial Purple degreaser. That made quick work of the carbon deposits. Look how intricate the valve mechanism is. So many tiny parts.
Next, the piston and rod got sonicated. It has a reed valve in it, which was installed with a "staked" retainer. Didn't want to disturb it so I cleaned it as an assembly.
The piston, connecting rod (or more properly "eccentric strap") and wrist pin. So many machined surfaces. This was hand fitted and assembled, I assure you.
The inlet reed in the piston. It's working fine.
The piston and rod back together. Ready for another 80 years.
The shaft after turning away the pitted surface. Note that I did have to rework it again. The flange part (from the original seal face) was in the way of the new seal. I had to machine that away completely.
All the parts about to go together again.
The gasket surface was in fair shape, considering what it had been through. I flat-filed it; and then glass bead blasted it. This will give the best surface for the formed-in-place gasket to bond.
The rotating assembly is together. Notice the brass thrust washers between the crankcase and eccentric hub? Those are now required, whereas the original mechanical seal provided a thrust stop in the original design. The shaft has about 0.005" end thrust clearance.
Now, a thin coating of Permatex Right Stuff goes in place. This will seal and bond the two halves of the compressor together. FYI this is not silicone. I believe it's a butyl type product. I have used it for auto A/C compressor applications with HFC refrigerants in the past and have seen good success with it. This is also what I used on my belt-drive Frigidaire.
The factory used an asbestos gasket, which succumbed to the SO2. It had become permeable and allowed SO2 seepage. The corrosion was apparent around the exterior of the gasket joint.
If you look just above the piston at the rear of the cylinder, you'll see the suction port cut into the side of the cylinder. This allows full flow into the cylinder at bottom center stroke. That bypasses the inlet reed valve and helps at high RPM or low suction pressure operation. Quite surprised to see this in a compressor of this age. That's getting high tech...
Here you can see the shaft, after I reworked it and machined away the flange. It's polished up and ready for the new Delphi dual-lip seal.
Seal installer thimble tool is in place over the shaft. This allows the seal to slide on, lip-down, into position.
Seal is in place!
Now the o-ring retainer plate and seal retaining cap are in place. Note the new hardware!
About to cut some new head gaskets. This material was bought from a local gasket shop. It is designed for semihermetic compressors, and is compatible with HFC refrigerants.
Ready to install!
A few minutes in the sonicator and this looks clean enough to use again.
All back together. Now to put it under vacuum and see if it holds overnight!
|
|
|
Post by ckfan on Oct 28, 2018 14:03:13 GMT
Top notch work as usual. It’s so interesting to see the insides of these. They look so well built aside from the leakage points. Makes me wonder if any of the later R12 units that they built survived better due to having a nicer refrigerant environment. This is very cool stuff.
|
|
|
Post by turbokinetic on Oct 28, 2018 15:09:49 GMT
Top notch work as usual. It’s so interesting to see the insides of these. They look so well built aside from the leakage points. Makes me wonder if any of the later R12 units that they built survived better due to having a nicer refrigerant environment. This is very cool stuff. Thanks Ray! I am sure that the R12 belt drive units would have aged a lot more gracefully. The problem is the rotating shaft seal. These wear out. The difference is that a leaked SO2 system is a corroded nightmare, whereas a leaked R12 system is just a system not working.
Speaking of leaked SO2 systems, I heard this song on the radio, and immediately a certain ruined Westinghouse compressor came to mind! youtu.be/q-RVJyNpfDk Remember that the belt drives "share DNA" with automotive A/C compressors. Those continue to be used to the day, as belt-driven systems. The seal technology has improved dramatically. The auto A/C systems hold a fraction of the amount of refrigerant and can work for 5 - 10 years or more before needing a top-up. Seal useful life is often 10 - 15 years even at the high RPM's the auto A/C runs.
I still firmly believe that hermetic compressors are the way to go; but if the belt drives had stayed in use, they would now be a whole lot more reliable. I'm hoping that the dual lip seals I am adapting from current auto A/C will be the ticket in improving the maintenance requirements of these Frigidaires.
The original design of the single-cyl Frigidaire compressor seal was a mechanical seal. It had two lapped faces which were forced against each other by a very strong spring. The manual for Frigidaire states (IIRC) about 40 pounds of force are exerted to press the faces of the seal together. Obviously there is a lot of friction involved, and a flood of oil would be very important to keep this from burning up. You can see in the pictures of teardown, how the seal faces seized and then the stationary part tore away from the backing plate.
The dual lip seal has a hard but stretchy cone (maybe Teflon blend?), with a rubber elastomer lip behind it. The rubber lip seal holds the oil and refrigerant in; while the Teflon cone conforms to the shaft, eliminating any gap around the shaft. The Teflon cone supports the rubber lip so that it isn't forced out between the shaft and the seal housing. Both the cone and the seal lip face inward towards the pressure source, so that additional pressure causes them to contract tighter around the shaft.
|
|
|
Post by turbokinetic on Oct 29, 2018 3:10:47 GMT
Well, after leaving the compressor under vacuum overnight, it was still at full vacuum this morning. That meant it was paint time! As with my 1931 model, I left the brass parts natural since they look better that way! The flywheel is painted Rust-Oleum 'Titanium Silver' color. It seemed to be a fairly close match to the silver galvanized coatings used on the other bare metal parts of the unit.
The motor had originally no internal protection device. There is an Allen-Bradley melting-alloy overload protector mounted in the control junction box. Unfortunately, it was not salvageable. The leaked SO2 had not been kind to the alloy parts, and they were just basically gone. Therefore, I placed a modern Klixon-type overload breaker inside the motor's junction box. The original protector is in place for a cover and decoration only. This protector will take care of any jammed up motor problems.
Installed new conduit since the original piece was rusty and broken.
The control got refurbished. It was all filthy and corroded. The movable switch arm was cracked, so I installed a reinforcement and soldered it together with solver bearing solder. The parts were corroded severely. To make it look somewhat presentable, I painted the control frame with the same paint as the flywheel and motor fan.
Clearcoated the motor nameplate. Note this is from the original motor, as this one had a defaced nameplate. But this shows 1/5 HP while the motor is actually 1/4 HP.
Belt is a modern part. The original belt was a modified-cross-section vee belt. It had a thinner profile than any current belt design. Also the inside surface of the belt was flat for running on the compressor flywheel. Modern vee belts aren't designed to run on a flat surface and have thick and thin areas. The belt used here is vee-ribbed but will work on a flat pulley without jerking. The motor pulley from the original motor (broken governor weights) was for a smaller shaft size. The one from this motor was rusted beyond use. I chucked its center hub in the lathe and removed the pulley sheave. Then, installed what you see here. It was a Ford alternator pulley.
I love the massive, industrial look this has. The commutator motor really looks the part.
The condenser was in impeccable shape. I just washed it with the pressure washer.
The control is so unusual compared to anything we have today!
I made a short video today, to show how it's coming together. Listen to this startup sound!
|
|
|
Post by ckfan on Oct 29, 2018 11:47:21 GMT
That sound is so cool. I’m glad to see this one coming together nicely.
|
|
|
Post by turbokinetic on Oct 29, 2018 13:56:11 GMT
That sound is so cool. I’m glad to see this one coming together nicely. Yes; that brush motor sound is really neat. So few folks even know what a repulsion-start motor is; let alone have heard one operating. Hopefully our current generation of young folks will find it interesting as well!
|
|
|
Post by turbokinetic on Oct 31, 2018 5:40:14 GMT
Update!
So, today I got some work done on this fridge. It continues to amaze me with its amazing cabinet condition.
First, the evaporator came out. It will need service.
Thankfully they don't appear too badly corroded inside.
This unit actually has service valves at the evaporator. Talk about serviceable. It's made so you can isolate the evaporator and remove it with refrigerant inside it if that becomes necessary.
The float. Unfortunately, this model is "simpler" than the 1931 I already worked on. As a result, there's no adjustment to it and that ended up causing issues...
Not so bad down in there. Just a little funky oil.
Eww! The needle valve is definitely No Bueno.
The parts. The white ring is the new gasket to replace the pre-crushed lead one.
Just look at the hideously grooved and worn needle valve tip! It's atrocious!
Tip reconditioned. Unfortunately, the needle is now too short, and the float has no adjustment on it.
Looks good, but in the end, adjustment was not possible.
Float assembled. The spring and cotter pin are in place so that the float will work with the less dense R152A refrigerant. This is the same spring and configuration I used on my 1931 which worked.
Pressure washed out the evaporator.
Going together, with new gasket in place.
Cleaned out the home for the condensing unit.
It fits!
While fitting the condensing unit, I baked out the evaporator under vacuum. It's basking in front of a heater.
Now the dryer goes in!
Cut that line....
Form it like so....
And solder in the Crap Trap!
Next, the sight glass goes in. This one will work, but I may install a brass, nicer-looking Supco one later. What you see in it is the beginnings of a charge going in.
Now the full charge is in! Looks empty, but trust me it's full of R152A liquid mixed with alkylbenzene oil. It's clear as water.
Pulling down. Problem is, it is backflooding some liquid to the compressor. The float needle is not working correctly.
First frost! Notice, however, the top line (the return) is frosted. That is not good and means the evaporator is overfilled with liquid. More float work is in order.
youtu.be/w_6c5RxLhj0
So, how does the unit sound with load on it? Here's a video to let you hear it!
Sincerely, David
|
|
|
Post by ckfan on Oct 31, 2018 14:24:09 GMT
That’s too bad that the float doesn’t have an adjustment. It does sound good though. Great work!
|
|
|
Post by turbokinetic on Oct 31, 2018 15:31:32 GMT
That’s too bad that the float doesn’t have an adjustment. It does sound good though. Great work!
Thanks Ray! It does sound good, to be honest! I was concerned the compressor might "jerk" because the flywheel is turning too slow and it is working against higher head pressure than originally intended. The 2-cyl compressors are much smoother. But my fears were unfounded and it's just fine!
It seems that Frigidaire was still in the learning curve about the float system. When I change to the adjustable style, you'll see how much more intricate it is. I had no trouble adjusting this style on my 1931 model.
|
|
|
Post by Travis on Oct 31, 2018 15:33:12 GMT
Yay!
|
|