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23 Cards in this Set
- Front
- Back
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What is the maximum unloading for a four cylinder reciprocating compressor? |
25% |
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8 cylinder can unload to 13%? |
Yep |
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Unloader forks do what? |
Keeps the pins up and the suction plate off the piston. |
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If you block the inlet suction what will happen to the gas inside the piston? Suction unloader |
It will get compressed repeatedly and get hot. They have a sensor on the head that will turn the cylinder back on to cool the head. |
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Unloading by Recirculating discharge? |
Moves some of the refrigerant to the low side. |
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Why do we put nylog on the spacers for the trust bearing? |
The back bearing bracket is the only one that is supposed to have shims on it.
If the shim doesnt stay in there tight. Use nylog to glue it on while installing so they dont move. Add a drop of oil on all bearing surfaces.
Look through the hand port tonsee if shims are in place. |
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Why do we put nylog on the spacers for the trust bearing? |
The back bearing bracket is the only one that is supposed to have shims on it.
If the shim doesnt stay in there tight. Use nylog to glue it on while installing so they dont move. Add a drop of oil on all bearing surfaces.
Look through the hand port tonsee if shims are in place. |
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How does the oil move theough the compressor? |
There is a sock on the oil pick up suction strainer. There is usually a magnet in the oil sump too. Oil goes through Strainer and to “back bearing bracket”, then out of the back bearing bracket through a tube and into the pump. Then it goes back into the “back bearing bracket” and into the back main bearing bracket. A oil line also heads towards the front oil bracket. |
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Why do we put nylog on the spacers for the trust bearing? |
The back bearing bracket is the only one that is supposed to have shims on it.
If the shim doesnt stay in there tight. Use nylog to glue it on while installing so they dont move. Add a drop of oil on all bearing surfaces.
Look through the hand port tonsee if shims are in place. |
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How does the oil move through the compressor? |
There is a sock on the oil pick up suction strainer. There is usually a magnet in the oil sump too. Oil goes through Strainer and to “back bearing bracket”, then out of the back bearing bracket through a tube and into the pump. Then it goes back into the “back bearing bracket” and into the back main bearing bracket. A oil line also heads towards the front oil bracket. Once the oil is at the main bearing there is a hole in the crank shaft and it will have holes in both “bearing shells” in the “big end” of the connecting rods. The connecting rods are riffle drilled and once every rotation the hole in the shell and the crankshaft line up. Oil will shoot through the connecting rod and into the pin bore and oil will shoot out the top and throw oil at the piston head. (Side of the piston is a skirt.) The oil ring on the scrapes oil off the oil from the side of the cylinder. Glazing is the oil that is stuck on the side of the cylinder and cannot be removed without effort (and scotch brights). When you replace the rings you need to remove the glaze. |
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The “back bearing bracket” is thick because… |
It has an oil pressure regulator in it. If you screw it in, a spring is pushed harder against a stem that pushes on a port. The oil will push against that port (in the opposite direction) and open the port if there is excessive oil pressure.
In to increase…. Oil pressure. |
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What kind of oil pump is on the compressor? |
-Positive displacement Internal gear pump or crescent pump Some have filters and oil coolers (higher compression machines) |
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What kind of oil pump is on the compressor? |
-Positive displacement Internal gear pump or crescent gear pump (auto reversing) Some have filters and oil coolers (higher compression machines) |
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Why is the key broken on the oil pump? |
The key is mated with the crankshaft end. |
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“S” means suction on the oil pump. |
True |
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The shaft drives the internal or external gear in the crescent gear pump? |
External gear |
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If you start up the pump and its not making oil pressure what do you do? |
Reverse the leads and see if it makes pressure in the opposite direction |
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If you measure in the middle of the main bearing what will you get? |
A bad measurement. Where there is a hole there is supposed to be no wear. |
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Oil failure controls are important? |
On start up. There is refrigerant in the oil and the refrigerant leaving the oil on start up causes frothing. |
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When you adjust the oil failure what happens? |
Cut in never changes. When you increase the differential you adjusting the point when the timer begins to time. |
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How does the recip unload? |
Normal operation: on the down stroke the suction valve ring will lift and refrigerant will enter the cylinder. (Because the suction pressure is greater than cylinder pressure). Then the piston moves up and suction valve closes against the seat because the cylinder pressure is greater than the suction pressure. The pressure will eventually overcome the discharge valve pressure allowing the discharge gas to leave. When the unloaders are inplay the unloader assembly have forks that push against a ring that push against the springs that lift the suction ring off the seat. You can remove the pressure on the forks ONLY when you have oil pressure. Unloader assembly is in the unloading position on start up. (Besides the forth cylinder.)
they move the suction valve (looks like a ring) off the seat where the suction enters the cylinder. Replace suction valve ring every time. The one cylinder that cannot be unloaded has a dummy ring that allows for the other cylinder in the bank to be unloaded. |
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Why do we check megs on a compressor windings? |
We check the megs annually so we can see the health of the windings over time! |
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How many stages is that centrifugal chiller in the back of the class? |
3 |
