When you hear the word “bearings”,
the normal prepper context is “a compass reading”. However, the other type
of bearings that a prepper should know about are the mechanical
ones that keep things spinning smoothly. Bearings are basically anything that
separates moving parts, reduces the friction between them, and limits
the direction of movement.
Knowing how to repair the things you use is part of prepping, so knowing a bit about bearings could be important.
Plain Bearings
A simple shaft or axle rotating through
a hole, with some form of lubrication used to reduce friction and
provide cooling; the lubrication itself is a plain bearing, which have been around for at least 2000
years and are still in use today because they're cheap and simple.
Plain bearings provide fair performance at a low price, but are best
used at low speeds and pressures. If you look at the wheels on a hand
cart or child's wagon you'll see a plain bearing where the wheel is
mounted on the axle.
Discrete plain bearings are often found in older
machinery; they look like a piece of pipe pressed onto the axle or
shaft and are often made of bronze or some other soft metal. If
you've ever rebuilt a car engine you've seen plain bearing where the
piston rods connect to the crankshaft. “Babbitt” bearings are a
plain bearing made by casting a soft alloy around a shaft where it
passes through a mounting block, but working with molten metal might
be beyond your abilities.
Jewel Bearings
Old mechanical watches and clocks often used small chips of extremely hard jewels as bearings to support the end of a spinning shaft. Under very low load and at low speed, these bearings will last for decades or centuries; maintenance isn't an issue, as they either work or they don't. I doubt very many of us will have the time, training, or equipment to work on jewel bearings, but they are a type to be aware of.
Exotic Bearings
This is my classification for the “other” bearings in use today. Magnetic fields and fluid (gas or liquid) flow bearings are high-tech designs for very high-speeds (dental drills use air-bearings at 250,000 rpm) or extreme environments (the vacuum of space), and require no lubrication or maintenance while providing long life. I don't have the tools or training to work on exotic bearings and can't think of anything in my daily life that uses them, so they're an interesting topic of research but not something I worry about.
Next week I'll go through the process of maintaining and replacing a set of roller bearings. The process is the same on a bicycle, a car or truck, a trailer, and a 20-ton wagon, so it's good knowledge to have. We invented the wheel to make things easier to move, so keeping those wheels spinning makes our lives a lot easier.
Packing boxes are a sub-set of plain
bearings and provide pressure sealing as well as friction reduction.
Where the shaft passes through a hole, a box or chamber is built
around it. That packing box is filled with some form of fibrous
material that has been infused with lubricant. A collar fitted around
the shaft is attached to the packing box with threaded rods and as
the threads are tightened, the collar compresses the packing around
the shaft. Common in older boats for sealing propeller shafts, you'll
also find packing box designs on high-pressure pumps.
Rolling Bearings
Both ball- and roller-bearings use a
rolling part inside a fixed collar to reduce friction and limit the
motion of a shaft. The fixed collar is called a “race” or
“journal” and is pressed into a precisely bored hole in the block
that the shaft passes through. The rolling element sits inside this
race, and the shaft runs through the middle of the rollers.
Ball
bearings work well at moderate speeds and heavy loads, but require
lubrication and maintenance for a long life. If you have a towed
trailer, you'll have wheel bearings to inspect and lubricate. Boat
trailers are notorious for consuming bearings because the axles get
submerged in water every time you launch or recover a boat.
Bicycles
are another place where you'll find rolling bearings; I've seen both
ball and roller versions in use. Automobiles have bearings all over
them, with the wheels and U-joints on drive shafts being the most
commonly repaired.
This is the type that I've been dealing
with lately, rebuilding trailers and the various rolling mechanisms
for agricultural equipment. Proper installation and maintenance makes them last
a lot longer, but it's a dirty, greasy job that my predecessors
neglected for several years. Common bearings aren't horribly
expensive, but finding the proper ones can be a challenge; when
things are measured in the thousandths of an inch, there is no “close
enough”, it has to be exact. Have spares on hand if you're going to
be doing your own work.
Jewel Bearings
Old mechanical watches and clocks often used small chips of extremely hard jewels as bearings to support the end of a spinning shaft. Under very low load and at low speed, these bearings will last for decades or centuries; maintenance isn't an issue, as they either work or they don't. I doubt very many of us will have the time, training, or equipment to work on jewel bearings, but they are a type to be aware of.
Exotic Bearings
This is my classification for the “other” bearings in use today. Magnetic fields and fluid (gas or liquid) flow bearings are high-tech designs for very high-speeds (dental drills use air-bearings at 250,000 rpm) or extreme environments (the vacuum of space), and require no lubrication or maintenance while providing long life. I don't have the tools or training to work on exotic bearings and can't think of anything in my daily life that uses them, so they're an interesting topic of research but not something I worry about.
Next week I'll go through the process of maintaining and replacing a set of roller bearings. The process is the same on a bicycle, a car or truck, a trailer, and a 20-ton wagon, so it's good knowledge to have. We invented the wheel to make things easier to move, so keeping those wheels spinning makes our lives a lot easier.
I think someone with more talent than I have could rework the song, "These are a few of my favorite things," into a version that names some of the types of bearings.
ReplyDeleteI'll add tilting pad thrust bearings to the list.
Really big thrust bearings that resist the push of an aircraft carrier's propellers.