[AT] Old shop lathe motor-- motor questions for you "experts"

[Larry D. Goss]

My dad designed electric motors for GE most of his career.  I asked him
about the big differences in size for the horsepower ratings even in the
"good old days" of over 50 years ago.  He launched off into an
explanation of current flow and hysteresis, DC vs. AC designs, shaded
poles, repulsion, and a bunch of other things that I didn't fully
understand (I wasn't even in high school yet).  But he said that the
basic design of the motor has as much control over the final size as
almost anything else.  A few years later, he used to mumble about having
to use "frog hair" for windings and all the production problems that
caused with regard to the service factors.  Dad would put together
prototype motors and send them out to the test unit.  When they came off
of "test", he would head out to the salvage yard at the plant and buy
his motors at scrap price (by weight).  He brought home some good and
fairly exotic motors for use on the farm.  Among others, he built GE's
first "glued" motor -- a motor that had no bolts and nuts on it, was
epoxied together at assembly and on which there would never be any
servicing or repair done.  One of the last motors he designed for them
in the late 50's was an alarm clock motor that could be manufactured for
12 cents.  The motors are still being produced, but the digital clock
market left the mechanical design in the dust.

I still have Dad's fan motor that he designed for cooling the condenser
coils on refrigerators.  He designed it in 1934, brought it home from
the plant after test, and we used it in the barn during the summer to
circulate air in the milking parlor.  For some reason, the fan was not
in the barn when it burned to the ground in 1950 so it survived.

Larry

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Greg Hass
Sent: Friday, January 20, 2006 10:59 PM
To: Antique tractor email discussion group
Subject: Re: [AT] Old shop lathe motor-- motor questions for you
"experts"

List traffic is a little slow, so I thought I'd put out a few comments
on 
this subject.  What I am going to say is based on both experience and 
things I have read.

In the past I had both beef cattle and hogs.  My feeding setup for
cattle 
required 10 motors ranging from 1/4-hp to a couple of 5-hp on the silo 
unloaders.  My grinding setup for hogs used 9 different motors ranging
from 
1/4-hp to 5-hp in various sizes.  I believe it is true that the old big 
motors were that way because they were American-built and were true 
horsepower/horsepower.  On one auger conveyor I installed a 1-hp motor
that 
my dad had purchased for a different use some 50 years ago.
Unfortunately, 
about 15 years ago the shaft spun in the ball bearing race and ruined
the 
motor shaft beyond repair.  I replaced it with a 1-hp Dayton 
motor.  However, if the conveyor became heavily loaded it would stop, 
whereas the old motor had carried it through.  After enough aggravation
I 
started studying the problem and found on the nameplate two 
letters.......S.F.    I found that that means "service factor", or the 
percentage of the motor's rated horsepower that it could put out 
continuously without overheating.  I found the new motor had a service 
factor of 1.0, and the old motor (which I still had lying around) had a 
service factor of 1.35, which meant the old motor had a lot of reserve 
power that the old one didn't.  I talked to a local dairy equipment
dealer 
who said he had run into the same problem on milking machine pumps.  He 
would replace a bad motor with one of equivalent hp, only to have it
keep 
overheating and stopping.  Then he'd have to go back a week later and 
replace it with the next bigger hp.  I then had to buy a 1-1/2 hp motor
for 
the conveyor and it ran almost as well as the old 1-hp.

As a side job, I also repair appliances and found about 10 years ago
that 
the newer motors would start smoking right away when overloaded, whereas
30 
years ago when I first started in the business they would hum but not 
smoke.  I could not figure out the difference until a neighbor (who
takes 
motors apart to sell for scrap) showed me the difference.  It turns out
95% 
of the appliance motors in the last 15 years have aluminum windings, not

copper, and cannot tolerate being run hot.  We have three of those
Baldor 
motors that someone was commenting on - two 5-hp on silo unloaders, and
a 
2-hp on a gutter cleaner.   Although we no longer use them, they are
still 
good and after years of use were never repaired.  They could be slowed
down 
to where they were barely moving but they would never stop, and would 
always slide the belt but not trip the circuit breaker.  It maybe true
that 
they are no longer available, but a few years ago when they still were
made 
an electrical contractor told me that a new 5-hp was around $2000.

I was in Tractor Supply the other day and noticed that Ingersoll Rand 
compressors are now listing 2-hp on the tank.  For example, it will say 
"running 5-hp, peak 11.5-hp."  HINT: If the nameplate on a motor does
not 
list the HP, or after HP says "spl" (meaning special duty),  you can be 
assured the actual motor hp is nowhere near the hp listed on the tank of

the compressor.

Just a few random thoughts for the evening.

Greg Hass
Bad Axe
from Michigan's snowy and getting snowier Thumb

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