I asked to hear a 14-inch gear-head Chinese lathe running at a dealers
today. Even at top speed (1800 rpm) it was really quiet, and I commented
on it. Yep, he said, we used to run them on 68 grade hydraulic oil, but
they were pretty noisy, so now we use 220 grade hydraulic oil.
This seems like a heck of a step up in viscosity. My knowledge of safe
oil practice and substitution is about zero, so... Is the change to 220
safe/good-practice/going-to-cause-problems/void-waranties, etc, etc??
It sure made it quiet!
Thanks
Roger Head
Interesting. I am rebuilding a 1972 Sheldon 15" lathes, a very high end
machine.
The oil specs in the book really had me wondering if there was a typo,
but there
is a plate on the machine with the same info. Basically, they run way
oil in
the headstock, and gear oil on the ways! I had to read the info a dozen
times,
and I still keep thinking I'm reading it wrong, somehow!
The only likely place you'd have a problem with the change in the Chinese
lathe is possible overheating at the highest speed. The ISO 220
hydraulic oil
is not all that much higher viscosity than the ISO 68. These ISO
numbers are
roughly 3.5 times higher than the SAE oil "weights".
Jon
I'm not an expert on this stuff by any means, but I still
wonder about the shear properties of hydraulic oil vs a good
gear grease. Now it probably wouldn't be an issue in a home
shop, but if you were using most of the horsepower of your
motor taking big cuts, wouldn't there be a problem with
gear wear?
Having ridden a motorcycle for a few years and having
experimented with different motor oils (which, BTW also
serve as the transmission grease as well), I found that it
was best to stick with purpose-formulated lubricants rather
than what ran the most quiet at idle.
I can't answer for the original poster, but this is what was recommended
by the manufacturer. The particular Sheldon headstock has no gears
meshing except when in the back gear range. (All the rest of the gears
are in another gearbox, that is lubed with heavy gear lube.) The back gears
are very big, 3/4" wide at least, and so may not need a very heavy gear
lube.
Motorcycles are another animal entirely, as they try to make the gearboxes
(and everything else) as small as possible, and running very hot at high
speeds. That makes them need a very high performance lube. (Running the
clutch in that lube puts them in a double bind - too good a lube and the
clutch
will slip, not a good enough EP lube and the gears grind themselves to
bits.)
Jon
What exactly does the plate recommend for the headstock? I
was confused the first time that I saw Mobil Vactra
specified for a gearbox til I did a little digging and
found out there are two Vactra lines. The numbered series
(No.2, for example) is waylube, the named (e.g., medium-
heavy) are general purpose oils.
If the ISO 220 oil in the original post is indeed hydraulic
oil, it's unusually heavy. I think it's more likely a gear
lube. ISO 220 would correspond approximately to SAE 50
engine oil or SAE 90 gear oil.
Ned Simmons
Ok, spoke to the dealer's engineer today, and yes, it is ISO 220 oil,
but not hydraulic oil - it's Shell OMALA 220 gear oil. There are plenty
of references on the web for this product. He said that in their
presses, guillotines, larger lathes, etc (anything that has force-feed
lube pumps) they use the normally recommended grades, but in the small
splash systems they use this 220 grade stuff. They move a lot of
product, and carry the warranty themselves (at least on this smaller
equipment), so I guess they don't see any problems when using it.
Like I said, it was the quietest 14 inch lathe I've ever heard - it was
like a big powerful sewing machine.
Thanks for everyone's input.
Roger
Roger Head wrote:
has a few interesting words, some of which I have extracted here:
"The Society of Automotive Engineers (SAE) is a viscosity grading system
for oils used in the automotive industry. To avoid confusion it is
divided into two subclasses, one for gear oils and one for engine oils.
A high number (greater than 60) means that the oil is formulated for a
gear type component while a low number corresponds to oil which is used
in the engine."
"Unlike the ISO system, the SAE system does not give the viscosity of
the oil in centistokes at 40°C, although the higher the number, the
higher the viscosity."
"SAE gear and engine numbers cover the same range of viscosities; for
example, an SAE 30 engine oil has approximately the same viscosity as a
SAE 85W gear oil. This is because the formulation of engine oils is very
different to that of gear oils in the automotive industry. An engine oil
is far more stressed than a gear oil because it must cope with
combustion by-products and blow-by gases which severely degrade the oil.
As a result engine oils contain a much wider variety of additives than
gear oils. Although not ideal, an engine oil will function in a gearbox
while a gear oil will destroy an engine."
Roger
Ned Simm> >
Heavy trucks used to use grease in their wheel bearings on the
front wheels and trailer wheels, and axle oil lubricated the drive
wheel bearings. Owners found that the oiled bearings outlasted the
greased bearings, as the grease just got thrown off or squeezed out,
and the bearing was dry. Front and trailer axles have used oil now for
nearly 30 years.
Grease is just oil with thickeners to keep it stuck to something.
It really doesn't have any more EP qualities than a good oil. If an
oil bath is possible, it's far better to use it.
Dan
What makes a good engine oil does not make a good gear oil, even though the
viscosity is the same. The differences are more in the additives then the base
oils, though there are different types of base oil. When the SAE number system
was invented, pre-metric, they need easy numbers to remembers (verse SUS
"something"-universial-seconds), and they picked 10,20, 30, 40, and 50 "weight"
to call motor oils, and 80, 90 and etc to call gear case oils so some "gearhead"
did not use the wrong oil.
The ISO 220 or 68 oils (there are quite a few numbers) are based on the metric
systems viscosity number, and is easier to remember.
Hope this helps
Vince
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