On Jun 21, 10:40 am, "Private" wrote:
wrote in message

ps.com...
On Jun 20, 12:31 pm, "Private" wrote:

wrote in message

roups.com...

I built my own
compressor years ago using an old truck compressor, and drove it with
a 1-horse 3450 RPM jet-pump motor.
Dan

How did you supply oil pressure to lube the crankshaft? or did this
compressor have its own closed sump and pump or splash lube system?

TIA

It was a base-mounted belt-driven compressor that was supplied
oil from the engine's oil system. I made a steel base plate to close
it off, drilled the side of the case and tapped it for a 1/2" 90° pipe
elbow for a filler/level check plug, and drilled and tapped the con
rod caps for 1/8" pipe street ells that acted as scoops to grab the
oil from the sump and jam it into the bearings. The main bearings were
ball bearings and get plenty of splash to keep them happy. The thing
has run happily for probably 100 hours over the last 20 years and
shows no sign of distress.

Dan

I have had good luck and extensive service from these compressors, but
always by mounting them on engines where I was able to connect them to the
engine's pressure oil and coolant systems. I used an electric clutch pulley
so they did not need to run continuously, IMHO they are very good
compressors. The current high cost of fuel makes it an expensive way to
obtain pressure air in any quantity unless the engine will be operated
anyway.

Happy landings.

This was an old aircooled unit, circa 1950, that showed up
in some returned cores. Instead of the usual unloader pistons that
lifted the intakes, it has intake ports in the cylinder wall that the
piston uncovered near the bottom of the stroke. The unloaders are
separate small valves in the head similar to small-engine valves,
opened by a lever operated by metal diaphragm that received the air
signal from the governor.
The whole design of these old compressors resembled an
outboard motor powerhead, and in researching the origins of Bendix-
Westinghouse compressors I discovered that the first units were
converted Evinrudes. So much for the similarities.
By the way: of the thousands of compressors we rebuilt, I
would say that at least half of the cores had nothing wrong with them
except for worn unloader piston O-rings, damage caused by a worn-out
$20 governor. New O-rings were a few cents. A shot governor doesn't
apply the unloading pressure suddenly, as it should, and the intakes
bang the lifting pins and work the pistons up and down rapidly and
wear the o-rings out. Leaky o-rings cause a pressure drop in the
governor when it cuts the compressor out, it thinks the tank pressure
has dropped, and it cuts in again so that the compressor is on/off/on/
off rapidly and the driver or mechanic thinks it's shot.
About a fifth of cores were those off Detroit Diesels and had
the phenolic drove coupling that would shear internally off its steel
hub but remain attached to the hub and look perfectly normal. It
couldn't drive the compressor, a compressor that had nothing wrong
with it.
And the rest had been allowed to eat dust through old/missing/
cheap air filters, and dust destroys a compressor faster than it will
an engine. It sticks to the thin film of oil on the cylinder wall
instead of being vaporized and blown out, and the cylinder and rings
eat each other.
Maybe you guys aren't interested in all this, but the point is
that most of our troubles with machinery are our own fault, either
through ignorance or just being plain cheap.


Dan