The big boys — VDOT and its road-plowing bretheren — they salt the pavement when it snows.
So, why can’t I do the same, with my driveway?
Turns out, the reason VDOT salts the roadway is completely different from the reason I salted my driveway.
Huh. Maybe you knew that, but I sure didn’t.
And as a corollary, recommended salt spreading rates for salting roadways have nothing to do with the amount of salt I needed melt the snow off my driveway.
Let’s not belabor this.
VDOT clears snow off the roads by plowing the snow off. Their goal is to plow down to bare pavement when possible. But they can’t do that if the snow and ice is stuck fast to the pavement. VDOT uses salt to keep snow/slush/ice from adhering to the roadway.
Hence, disbondment. The act of taking ice and snow that are frozen hard to the underlying pavement, and getting them loose. Dis-bonding them from the underlying pavement.
Typically, VDOT’s goal is to use salt to melt just the very bottom layer of the snow/ice pack, where that touches the pavement. They want to weaken that interface, so that the snow/ice can be scraped off with a normal snowplow.
I, by contrast, was using salt to clear the pavement. That is, I wanted to melt the entire predicted thickness of the coming snowfall. That, because I specifically didn’t want to scrape the snow and ice off the pavement. I wanted them to run off, as salty water. (I admit that I was right tired of shoveling, at this point in our most recent winter storms.)
Guess what? If you’re only trying to melt that very thin interface between snowpack and pavement, a) you’re happy to use snow-melt pellets that just melt a little hole in the snow, until they get down to pavement, and b) overall, disbonding-then-plowing uses a lot less salt than melting the full thickness of the snow pack with salt.
A typical manufacturer recommendation for home use of de-icers (e.g., rock salt, calcium chloride pellets) works out to around one 50-pound bag of salt for every 1000 square feet. Whereas the (reportedly) most common recommended rate for VDOT salting the road is about five pound per 1000 square feet.
Conclusion
There are a few fairly big conclusions, from the simple observation that VDOT’s use of salt and my use of salt are not at all the same.
First, just because VDOT salts the roads doesn’t mean I have an excuse to do it. If for no other reason, what VDOT is trying to do with salt (disbondment of snow/pavement interface) has nothing what I’m trying to do (melt the entire thickness of the falling snow).
Second, you can’t take recommended salt spreading rates for road use, and apply those to melt the snow off your driveway. It’s not nearly enough salt. You will end up committing homeopathic ice melting, as described two posts back.
Third, using salt to melt snow in bulk — say, the full thickness of a light snowfall, off my driveway — that may be a remarkably stupid thing to do. Again, per square foot, it takes vastly more salt to do that, than it does to treat the roadways.
While my road salt is but a minor contributor to the problems caused by society’s reliance on road salt, there’s no point in my adding fuel to the fire, needlessly. Maybe in some climates, some locations, you absolutely have no choice but to use road salt on your driveway and walkways. But Virginia, USDA Zone 7B, ain’t one of them.
I may take one more stab at this topic, trying to assess environmental safety of various road salts/ice melters.
And I may not. Environmentally, the best choice is to use nothing. So I’m not really feeling compelled to suss out various road salts’ claims of environmental friendliness or minimal impact on machinery and the built environment.
I am still trying to get up to speed on ice-melting compounds. So far, two things appear crystal clear.
First, rock salt — sodium chloride, NaCl, halite — is the worst ice-melting compound, in terms of metal and concrete damage, environmental harm, and pet safety.
Second, most of the claims, made by most ice melters, are, at best, exaggerations.
Pet-safer: Crossing the line on exaggerated product claims.
But some ice-melter claims — particularly regarding “pet-safe” and “eco-friendly” — are purposefully deceptive.
And, oddly enough, those purposefully-deceptive claims of “pet-safe” and “eco-friendly” ice melts work exactly the same way. In order to be legal, they only claim to be pet-safer or eco-friendlier. Than what, you might ask? Than pure rock salt. So the first takeaway is that anything that’s even trivially better than pure rock salt — such as rock salt with some tiny amount of additives — can advertise itself as both “pet-safer” and “eco-friendlier” (…. than rock salt).
Surely we agree that rock salt is not pet safe?
By way of making this as clear as possible, let me narrow it to dogs. And focus on the bottom of the barrel — rock salt.
A dog will get sick if it ingests too much (table, NaCl) salt. One reference listed a dog-lethal dose of sodium chloride (salt) as 4 grams per kilogram body weight (Source: Veterinary Toxicology, 4th Edition.) Thus a 30-pound dog that manages to eat two ounces of rock salt, and keep it down, might reasonably die from doing that. (That’s about three level tablespoons of table salt.)
And a dog could pretty clearly get sick from a lower dose than that. Salt poisoning leads to vomiting, diarrhea, and, if it proceeds far enough, to neurological symptoms (e.g., inability to walk).
Salt poisoning of dogs does not appear to be very common. Another reference said that in 1998, there were just 50 such cases reported to ASPCA poison control hot line. Currently, salt poisoning doesn’t make the top 10 list of common pet poisons.
And, from reading a few case reports, ice-melt poisoning can occur if a dog takes a big gulp of the stuff, straight out of the bag. But, in general, that’s not the problem being addressed by use of “pet-safe” de-icers. A mouthful of de-icer is going to be bad for your pet, no matter what.
Instead, people who buy pet-safe ice melt are worried about dogs walking on areas treated with (e.g.) rock salt as an ice-melter. First, salt irritates dogs’ paws. And second, dogs ingest salt from licking off salt crystals stuck on or in their paws,
The upshot of all that is that rock salt (NaCl) is something you don’t want to see in a “pet-safe” ice melt.
So what do I find, off the crack of the bat, on the Home Depot website?
And that’s not a one-off accident. Here’s the same nonsense from Uline, a supplier of industrial products of all types:
So …
Once you move beyond colored rock salt — clearly not pet-safe — there’s some real ambiguity as to what’s safe or not.
Urea is typically considered fully safe for dogs and cats (but is not safe for ruminants). But urea is basically high-potency nitrogen fertilizer.
I can’t see myself dumping a 50-pound bag of 43-0-0 fertilizer on the driveway in winter. Or in any season, really.
Plus, it’s a poor ice melter, and you’d be hard-pressed to find it bagged in bulk for consumer ice-melt use. Apparently, it is only commonly used in specialty situations such as elevated metal walkways, where lack of metal corrosion is the key concern for the ice-melt.
Acetate ice melters (calcium magnesium acetate (CMA) and potassium acetate (KAC)) are considered pet-safe by some. But these, too, perform relatively poorly as ice-melters, and are expensive per effective melting dose, as well. They have the additional advantage of not being chloride salts, and so being less toxic to the aquatic environment than (say) rock salt.
Beware “with CMA”, just as you should beware pet friendlier. A lot of ice-melt blends want to bask in the glow of CMA without the bother and expense of actually including much of it in their blend. (Plus, the ice melter probably works better as an ice melter if you go light on the CMA, because CMA apparently is not a very good ice melter. It just has the big advantage of killing less stuff than chloride salts do.)
Magnesium chloride is considered safer for pets than other chloride salts. It is sold, for example, by both PetSmart and PetCo as a pet-safer de-icer. It also performs quite well as a de-icer. From a pet-safety standpoint, the only drawback appears to be price. In retail packaging, MgCl2 appears to cost anywhere from five to ten times as much as rock salt. But, as a chloride salt, this is not materially better than rock salt, from the standpoint of toxicity to the aquatic environment. And some references suggest that it causes more damage to concrete than rock salt does, particular to newer (under-one-year-old) concrete.
Conclusion
I have no dog in this fight, if you will excuse the phrase. I don’t own a pet, so this isn’t my problem. I only stumbled across it in looking for ice melts that aren’t chloride salts, hoping for lower environmental impact. And was vaguely outraged once I figured the whole pet-friendlier thing as discussed above.
But I note that it is a common and accepted practice in the ice-melt market to take a bag of common rock salt, color it (green or blue, inevitably), sprinkle in some actually pet-safe materials, slap “pet-safer” on the bag, and then double the amount charged for it.
Unlike pet food, nobody appears to regulate anything about “pet-safer” de-icers. Even though the danger arises from pets eating the stuff. Contrast that the the multi-agency Federal regulation of pet food. (Not that the Feds need to regulate de-icers per se, but the use of “pet-safer” and similar legal-but-misleading claims.)
Unsurprisingly, then, a lot of stuff offered in the big-box hardware stores as “pet-safer” ice melt is just rock salt (plus a tiny amount of additives) sold at a steep markup.
I’m no longer going to use pavement de-icer (rock salt, road salt, ice melt).
For now, at least.
That’s because, upon inspection, much about the modern road salt/pavement de-icer market confuses me.
But in my defense, I had a lot of help, getting confused. The whole retail “de-icer” market pings my bullshit detector in some strong and unpleasant ways. Not just the simple stuff (“melts as low as … ). More importantly, “pet-safe” and “eco-friendly” have quietly morphed into their mealy-mouthed “safer” and “friendlier” versions. And not in a good way.
Road salt is a deep topic, but I have to start somewhere.
As described in Section 1 below, I did not intend to fuse the principles of homeopathy with those of winter pavement maintenance. That happened entirely as a result of my own stupidity.
But, per Section 2 (next post), I had a lot of help being stupid about it. Pavement de-icers are arguably the worst consumer product I’ve ever seen, in terms of manufacturers’ claims and deliberately misleading marketing.
Plus, Section 3, the practical use of chemical pavement de-icer is complicated. Even absent all the baloney presented by sellers of de-icers, there’s a lot to unpack. I’m not sure I understand the chemistry part of it, yet, let alone the weather’s contribution.
And, Section 4, most (perhaps all) commonly-used de-icers are crap for the environment, especially the aquatic environment. I can’t complain about the taste of road salt in the drinking water if I’m spreading this stuff on my own driveway.
This is just the first of several posts on pavement de-icer.
A few days ago, I salted my driveway, using calcium chloride pellets. The idea was that the (calcium chloride) salt would melt a coming light snow, causing it to run off my driveway as (slightly salty) water, and, ideally, leaving me with bare pavement. Instead of a driveway with an inch of snow on it. This, as being preferable to re-shoveling my driveway to remove a light coating of snow. And this to be achieved despite temperatures consistently (but not hugely) below 32F.
By the end of the next day, my driveway was dry and snow/ice free.
So the salt obviously worked, right? End-of-story.
Part 2: But … science
As I was patting myself on the back, I could not help but notice that all my neighbors’ driveways were also dry and snow-free.
Which, after a moment’s solemn reflection, pretty strongly suggested that my salting my driveway was a complete waste of time.
I’m pretty sure none of my neighbors salted theirs.
Part 3: thus was born the short-lived science of driveway homeopathy.
First, I found a pretty chart. (This is, in fact, an excellent chart from an excellent practical reference.)
Source: National Tank Outlet. These folks sell the tanks you need to store this stuff at industrial scale.
Those substances are all salts, chemically speaking:
And then, only as a last resort, actually reading the directions on the bag. Which, they just flat out say, per for 1000 square feet, for some “typical” conditions (I guess), I should use just touch more than what I calculated above.
The upshot is that I should use at least an entire 50-pound bag of calcium chloride. On a 1000-square-foot section of driveway. That, to get rid of an (one) inch of typical snowfall. That should make a brine strong enough to have all that snow turn to water and run off, even though the weather is (maybe) 10 degrees below freezing. This, instead of shoveling the driveway, again, for the new inch of snow that fell.
I’ve never used it at anything close to that rate. I use it a few pounds at a time. (And, correspondingly, my first (and current) bag of calcium chloride is at least a decade old.) Nor will I ever.
Ergo, I have been engaging in homeopathic ice melting. Sure, I start off with strong brine, when those first few snowflakes hit those salt (calcium chloride) crystals (pellets). Implicitly, I must have believed that after adding a whole lot more water (in the form of an inch of snow), the resulting very dilute brine would somehow recall the strength it once had, and so continue to melt the snow.
Contrary to the laws of physics and chemistry. Or common sense.
Or the directions on the bag.
Or all of the above.
Conclusion
For now, the simple message is that homeopathic pavement de-icer helps no-one. Avoid it.
It achieves nothing while causing slight environmental harm. It’s a net negative, except perhaps in (easily deceived) the mind of the user.
So, with regard to salting the pavement: Do. Or do not.
Crazily enough, I have a lot more to say about ice melters. That’ll come out in the next posts.
In Vienna, VA, we are religious about shoveling the snow off our sidewalks.
God put the snow there.
God will remove it when he’s good and ready.
I tried to take a walk yesterday morning …
… without walking on snow and ice.
But, because I live in the Town of Vienna, that meant spending a lot of time walking in the road.
There’s no requirement to shovel your sidewalk in the Town of Vienna. Unsurprisingly, some sidewalks are shoveled, some aren’t. Which means that you typically can’t walk the length of a block without either walking on an un-shoveled sidewalk, or walking in the road.
This got me to thinking about what the snow-clearance laws are in Northern Virginia. I know there’s no ordinance requiring it in Vienna. But what about the rest of Northern Virginia?
Turns out, Vienna is in the minority. Most of the jurisdictions around here require residents and business owners to shovel their sidewalks promptly after a snowfall.
I find that to be an oddly mixed bag. Loudoun County is in general far more rural than Fairfax County, yet they require snow shoveling while Fairfax does not.
In all cases, the penalties for failure to clear a sidewalk are nugatory, so it’s not clear whether any of the laws are or are not effective. I considered taking a field trip to the People’s Republic of Falls Church to see if their sidewalks really do get cleared or not. But it hardly seems worth it. Give it another few days, and the snow will be gone.
In the end, it’s just another oddity of living in No. Va. These jurisdictions all have the same weather and have pretty much the same population demographics. I’m guessing that the presence or absence of a shoveling ordinance is mostly a matter of historical accident.
In any case, in Vienna, we clear our sidewalks the old fashioned way, via religious observance.
Addendum: Businesses in Vienna VA?
I know there’s no ordinance requiring homeowners to shovel their sidewalks in Vienna, but I was immediately questioned about businesses. You can, and many places do, have different shoveling laws apply for business versus residential.
Old news reporting says that Vienna Town Council turned down any sort of shoveling ordinance in 2011 (Reference The Patch).
And that’s the last Google seems to have heard of it.
A search of MuniCode for Vienna VA for snow yields 13 mentions, none of which have to do with requiring businesses to shovel snow.
A search of the Town Website yields nothing useful, but that’s never definitive.
For sure, the Maple Avenue sidewalks were cleared around here. Here’s Pleasant and Maple, looking west and east.
So, I don’t know. There doesn’t seem to be an ordinance requiring it, but something resulted in the clearance of the Maple Avenue sidewalks in my area. This is distinctly different from (say) Nutley, also a multi-lane road, but with large sections of un-shoveled sidewalk.
If it’s due to an ordinance, that ordinance appears well-hidden.
Finally. I finally opened the hood of my 2020 Chevy Bolt, a year after I bought it (Post #1924).
I never saw a reason to look under the hood, figuring I’d have no idea what I was looking at. It being an EV, and all.
Now that I’ve opened the hood, I was not disappointed.
Not ringing a lot of bells with me. I think I recognize a brake master cylinder and tan plastic reservoir mounted to the firewall, driver’s side. But all those big metal thingies? No clue.
Luckily, one can be ignorant and still drive a car. That, proven daily, I’d say.
Even now, I wouldn’t have bothered to open the hood, ever, except that with the recent winter storm, and the resulting sloppy roads, I figured I should top off windshield wiper fluid. Seeing as how that hadn’t been done in a year.
I was able to do that without reading the manual. The hood release was in an obvious place, the hood emergency latch was easy to find, and (shown below) the right place for windshield wiper fluid is pretty clearly marked. Even had a hood prop where I expected to find it.
So thumbs up to Chevy for making that much obvious.
Weirdly, I swear there’s a fan and radiator in there somewhere. For sure, there are several little reservoirs that look like they hold coolant. Plausibly that’s all part of whatever manages the temperature of the battery and the electronics.
It’s magic, as far as I’m concerned.
Plus it runs at a lethal 350V DC. As long is to works, leave it be.
It says something deeply, deeply weird about the soul of America, that people are panic-buying toilet paper in response to the East and Gulf Coast port strike.
I had a few responses to this, in no particular order.
First, guess I’m glad I haven’t worked my way through my pandemic stockpile yet.
Second, maybe I had better pick up some toilet paper at the store today. Just in case.
I fully realize that toilet paper doesn’t move through these ports. Almost all toilet paper used in the U.S. is produced domestically, call it 93% (reference Yahoo). The rest that is consumed in the U.S. is produced in Canada and Mexico, and isn’t shipped by ocean-going freighter.
And yet, it’s a fallacy to say that toilet paper should be unaffected by the port strike. If enough people are stupid and irrational about it, and the target of their stupidity is toilet paper, then toilet paper is very much affected by it.
Oddly, if you substitute “Springfield, OH” for “toilet paper” in the last sentence, it still makes perfect sense.
Anyway, the consequence being that if you need to buy TP, you’ll be every bit as much out of luck, even though a shortage is purely a result of irrationality, as if there some actual disruption of the toilet paper supply chain.
Some consumer items will likely go out of stock from this strike. Bananas being the poster child for that. But who would have guessed that TP remains the canary-in-the-coal mine for American anxiety.
It took about an hour to construct the vehicle and foot traffic counts you see here. The hardware was an $18 Kasa camera, plus my laptop to view the resulting footage.
I let the camera film the street in front of my house. That was not intrinsically different from (e.g.) a Ring doorbell. (It is legal in Virginia to film anything in the public right-of-way, or anything you can view while in the public right-of-way, other than restricted areas such as military installations, as long as you don’t record conversations that you are not part of.)
I then did the simplest thing possible. I transferred the SD card from camera to laptop, and watched the video on fast-forward. It was like the worlds most boring, yet tense, home video. I stopped the film when something happened, and put down tally marks.
The fastest I could comfortably watch was 16X. Doing that, recording the events in eight hours of video took about an hour. (The camera itself is capable of noting the passage of cars, via built-in motion detection, but would not identify passing pedestrians at the distance this was from the street.)
If nothing else, this confirms what my wife and I had both noticed, that this street is used by a lot of dog-walkers.
This is just a proof-of-concept. Today it’s drizzly, and there’s a school holiday, so this would not be representative of typical Friday morning foot traffic.
The context is the value of sidewalk improvements in the Town of Vienna. With rare exception, there are no counts of pedestrian traffic in any of the Town’s various studies. (I did find one, once, but they referred to rush-hour pedestrian street crossing counts along selected corners of Maple Avenue, our main thoroughfare).
The idea being that there’s more value in putting a sidewalk where people will use it, than putting it where they won’t. Assuming that current foot traffic along a route is a good indicator for eventual foot traffic there, once a sidewalk is built. (There could be exceptions to that. But in the main, I think that’s right.)
And that, for planning purposes, you’d like to have some idea of what they’re using a particular route for.
There are currently at least two ways to get pedestrian count data on (e.g.) suburban side-streets that do not have traffic lights. Other than the old-fashioned approach of having somebody sit by the street and count passers-by.
One is to use cell-phone data, because many cell phones track and report their user’s location on a flow basis, and that information is sold commercially. Courtesy of the improved accuracy of GPS, data vendors can now tell you (e.g.) how long the average customer walks around a store, based on how long their cell phones linger there.
(I am not sure that this tracking is entirely “voluntary” or not. That is, did you download an app that, had you bothered to scrutinize the dozens of pages of fine print before clicking “ACCEPT”, would have revealed that you gave that app the right to collection and transmit your location to some central source? Or, just as plausibly, if you don’t manage to turn off every blessed way that your phone can track you, then somebody’s picking up your location on a flow basis, you just have no clue whom? For sure, the phone companies themselves always have a crude idea of where your phone is (based on which cell tower your area nearest), and I’m pretty sure they also get your GPS data, nominally so that they may more accurately predict when your signal needs to switch from one cell tower to the next.)
The problem with counts based on cell-phone tracking that it is of an unknown completeness. Plausibly, some people manage to keep themselves from being continuously tracked. Or, more likely, any one data vendor only buys that data from a limited number of app providers. Generally, it’s fine for making relative statements about one area versus another, but needs to be “calibrated” to real-world observations in order to get a rule-of-thumb for inflating the number of tracked phones in an area, to the actual on-the-ground pedestrian count.
Plus, it costs money, and it’s geared toward deep-pocketed commercial users.
Finally, it’s likely that certain classes of pedestrians will be systematically under-represented in cell phone data, most importantly school children, but also possibly joggers.
The other way to do it in the modern world is to use a cheap camera. Then count by eye.
So, as an alternative, I decided to see how hard it would be to gather that information this way. Turns out, it’s not hard at all, even with doing the counts manually. All it takes is a cheap camera, my eyes, and, for eight hours of data, an hour of fast-forwarding.
Not sure where I’m going with this, in the context of writing up the multi-million-dollar make-over of my little street. I just wanted to prove that it’s not at all hard to get data-based counts of pedestrian traffic on any street. All you need is a camera, and a place to put it. And the time to view the results, if you can’t figure out an automated system for that.
My approach may be a bit low-tech for the 21st century in the surveillance state. But it works. Fill in the hourly wage of (say) the employee who would have to watch that video, and you come up with a pretty cheap way to provide hard data on need for sidewalks, as evidenced by counts of pedestrian foot traffic.
If you’re going to spend millions of dollars on sidewalks … how could you not do this first, to see that the expenditure is efficient, in the sense of pedestrians served per dollar of expense?
More on this still to come.
Coda
As if to underscore the power of the surveillance state, about six hours after I posted this, I got my first-ever email from Kasa, with an offer for a video doorbell.
That, presumably, because this blog post had the words “Kasa” and “doorbell” in it.
This happens enough that I know the root cause of it.
Sure enough, yesterday I signed into Google, using this browser, to access something via my Google account, and I foolishly forgot to sign out. Google was therefore somewhat aware of just about everything I did on this browser in the meantime.
Presumably Google ratted me out to Kasa.
Somewhere, the ghost of Orwell is surely laughing.
Recap: This is a series of posts about replacing the fork bearings on a TiLite Aero wheel chair.
In the first post, I removed the forks from the chair. What should have taken about five minutes actually took several hours, owing to a bearing that was rusted solid onto the fork axle.
In the second post, I worked through all the details on bearings. As long as you know the size of the steel sealed bearings that you need, you can pick them up for around $1 each on Amazon.
This third post is about driving the old bearings out of the fork, and pounding the new bearings into the fork, using only these tools and materials:
a soft vise to hold the forks as needed (I used a Workmate bench).
The snap-ring pliers are not optional, unless you’ve got a whole lot more dexterity than I do. There is one c-clip in each fork, whose purpose is to ensure that the bearings do not slide down from the weight of chair and user. That c-clip is difficult to get in or out without c-clip pliers.
Also, be warned that driving the bearings in with a hammer and “drift” is not for the faint of heart. You end up hammering pretty hard. About as hard as you might when pounding a nail into a 2×4. You have to do that, to get the bearing to seat all the way at the bottom of the hole it fits into.
If the very idea of hammering that hard on an expensive wheelchair part makes you squeamish, then you’ve got good sense. This is nobody’s idea of a good time. But once you’ve started this, either you drive that bearing all the way home or you buy/make a bearing press that can finish off what you started.
If I had to do this multiple times, I’d shop for a bearing puller (to take the old ones out) and a bearing press (to push the new ones in) before I started the repair. There are also kits specifically marketed for common wheelbearing sizes (e.g., a kit for pulling and pressing in R8 bearings).
But you can do it with just the crude tools listed above. That’s how I did it, for this one-off repair. That’s really the point of this post.
Get the old bearings out using screwdriver and hammer.
The basic idea is simple. You’re going to push the top bearing out of the top of the fork. (As shown above, you’d be pushing it from below, so that it moves toward the camera.) Then remove the c-clip, using c-clip pliers. Then push the bottom bearing out of that same opening.
In other words, the top bearing comes out first, then you remove the c-clip, then the bottom bearing comes out. And all of that comes out of the top hole in the fork.
To achieve this you:
Flip the fork over (from what is shown above), and hold it in some fashion. I used a workbench as a soft-sided vise. If you are careful, you can simply rest the flat top of the fork on a couple of cutting boards, or chunks of wood, but you must leave the full width of the hole unobstructed so that the bearing can come out.
Insert a flat-bladed screwdriver through the bottom of the fork (the side away from you, in the view above).
Catch the corner of the blade of the screwdriver on the inner bearing race of the top bearing. (The one nearest the hole that these must come out of).
Give the screwdriver a sharp tap.
Move the screwdriver so that it catches the opposite side of the inner bearing race of the same bearing.
Give the screwdriver a sharp tap.
Move the screwdriver blade back to where you started.
Repeat 2 – 6 until the bearing falls out of the top of the fork.
You keep moving the screwdriver from side to side, as you tap these bearings out, to try to ensure that the bearing stays level within the fork — perpendicular to the axis of the hole in which the bearings sit. The last thing you want is to get the bearing wedged kitty-corner in that hole.
What makes this hard is that these are interference-fit bearings in a metal casing. The hole they fit in — in the fork — is just slightly smaller than the diameter of the bearing. So, while the bearing is friction-fit to the housing, there’s a lot of friction involved.
Which means, in no uncertain terms, you are going to have to tap these vigorously to get them to move. And yet, not so hard that you break them.
How much force? Take a look at this fellow, around 30 seconds into the video to get an idea of what a “tap” is likely to be, for driving a steel bearing out of a metal bearing housing:
He doesn’t bother to move the screwdriver from side-to-side for that particular bearing. But you will want to do that here, particularly for the second bearing, which has to travel quite a ways before it is free.
A better view: This next video provides an excellent view of what you’re trying to do with the end of the screwdriver, at around 1:10 into the video. (Though, this particular bearing came out quite easily.)
Too easy: Here’s yet a third example of this technique, around 30 seconds into this video, where the bearings are driven out of a plastic wheel. You’ll have to hit harder than this to drive them out of the titanium fork.
I hope that gives an adequate feel for the process. Catch the edge of the back side of the inner bearing race with a screwdriver. Tap with as much vigor as necessary to move the bearing. Move the screwdriver from side-to-side on the bearing to help keep it aligned within the bore. Keep tapping until the bearing drops out.
Remove the c-clip. And do the same thing to the other bearing.
Clean up, grease up, test the fork axle.
Clean any gunk out of the inside of the fork. It is particularly important to make sure there is absolutely nothing stuck in the “corner” of the bottom of the hole.
Why is that important? Above you see the c-clip groove, inside the fork. The first bearing you put in must be driven completely below that groove. Then you place the c-clip in that groove. Then you drive the second bearing into the rest of the space. If the first bearing doesn’t sit absolutely flat on the bottom of the hole, you won’t be able to get the c-clip in. And that, in turn, prevents you from correctly re-assembling the fork.
Wipe any gunk off the c-clip at this point, as well. Just for good luck.
Coat the inside of the fork with a layer of thin grease. I think lithium grease is what is what is typically recommended. Some say that this helps prevent the bearing from seizing in the fork, so that you can get it out next time. I say it helps lube the bearing going into the fork, because you’re going to need all the help you can get to drive the bearing all the way into the fork.
So spray a little grease in, move it around, then swab it out with a paper towel. You want just the thinnest possible layer of grease.
Test to see if the new bearing will slide over the fork axle. You’ll note that I barely bothered to clean up the axle. In particular, I don’t want a nice shiny raw metal surface on that axle, because that just invites corrosion. Leave it alone if you can. The only thing that matters is that the new bearing can be slid over it. Assuming it does, slide the new bearing off, and apply a thin layer of grease over the fork axle. Wipe off any excess with a paper towel.
A brief calculation on freezing the bearing and heating the fork.
I’ve driven bearings like this many times. It’s always a stressful process. I’ve learned to take every advantage I can, if I’m unsure that I can drive the bearing into its housing properly.
Common advice for this next step is to put the bearings in the freezer to cool them, and take a heat gun to the bearing case (the fork, in this case) to heat it. The idea is the take advantage of the coefficient of thermal expansion of metals, and give you a little extra room as you are driving the bearing.
Based on this reference, and my calculation, taking a 1 1/8″ diameter bearing from 70F down to 0F, while heating the titanium housing an equal amount, should increase the clearance for the bearing by almost a thousandth of an inch.
Believe it or not, it is well worth doing that, given that these are more-or-less zero clearance bearings.
If you are unsure of your ability to drive this bearing into this housing, go ahead and take the time to freeze the bearing, and use a hair dryer or heat gun to heat up the fork.
If nothing else, it’ll give you the courage to bang all that much harder at the next step.
BUT THIS COMES WITH A WARNING: WORK FAST. The coefficient of expansion of steels is higher than that of most titanium alloys. The upshot is that if you heat both the titanium fork and the steel bearing, the steel bearing will expand more than the titanium hole. The bearing will actually get tighter, not looser, in that hole. So if you’re going to try this freeze/heat trick, you need to get the bearing seated before it warms up to the temperature of the titanium fork.
As a compromise, you could just freeze the bearing, and leave the fork alone. That will help some, and there’s no harm done if the bearing warms up to room temperature during this process.
Bearing abuse, or using a drift to install the new bearings.
Normally, at this stage, you’d say “installation is the reverse of removal”, and leave it at that.
But in this case, that’s wrong.
To be clear, what you just did to remove the bearing — pounding on the center bearing race — ruins the bearing. At least, if you beat on it hard enough it will. All the force of your hammer blows was transmitted through the “innards” of the bearing, in order to get the outer race to slide along the bore in the fork.
You are NOT going to do that when driving the new bearings back into the fork. Instead, you are going to drive the new bearings by beating on the outer bearing race only. Never on the inner bearing race. That way, the force of your blow is transferred through the steel race directly to the side of the hole. And you are not counting on the “innards” of the bearing to transfer the force of your blows to the outer race.
Clear enough? These bearings come out one way, but they go in in a different way. Beat on the outside race ONLY as you put them back in, because you don’t want to break your brand new bearing.
This is where you need to find a drift for your bearing. A drift is some sort of sturdy hollow metal cylinder that’s just a fraction of a hair smaller in outer diameter than your bearing. The idea is that as you beat the bearing down into the fork, using the drift, it only beats on the outer bearing race, and does not press on any of the “innards” of the bearing. You can buy sets of drifts in graduated sizes on Amazon. But, typically, you’ll use a socket, out of socket set.
Beating the first bearing flush.
Here are the issues.
First, you’re beating a metal bearing into a metal bearing housing — the fork. That’s going to take quite a bit of force. And the further you beat it into the fork, the harder you have to hit it to move it. So, you start off with taps, and you end up with hammer blows.
Second, until you have the bearing flush with the opening, it’s critical to keep the bearing level — going in evenly all around. Stop every so often and eyeball the bearing. If it’s high on one side, tap that side down, and then carry on. So, center the bearing on the opening, nice and level, and start with gentle taps — on the outer race only. (If you have a brass-faced hammer, this would be a good use for it. I used a steel carpenter’s hammer.)
Eventually, you’ll get the bearing driven flush. That’s when you need to center the drift on top of the bearing, and start pounding it home. No more tap-tap-tap. At this step, it’s bang-bang-bang. You must drive this all the way to the bottom of the hole or you won’t be able to re-assemble the fork correctly.
Once you have the first bearing driven home, use your c-clip pliers (and fingers, and screwdrivers) to get the c-clip firmly seated in the groove. There are no style points here — however you can get the clip to seat in the groove, that’s fine. Note that once the clip is correctly in the groove, almost all the clip is hidden.
Finally, drive the second bearing in flush with the surface of the fork. Same process as the start of the first bearing, being sure to tap-bang only on the outer bearing race.
Pat your self on the back if the result looks like this. The outer race is flush all around. And nothing is obviously broken.
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You’re done
Slide the fork onto the fork axle, put on the washer and retaining lock nut. Tighten the lock nut just enough to keep the fork from rattling.
And you’re done.
If all this pounding on expensive metal parts is off-putting, consider using bearing puller/press designed for this size of bearing. For sure, if I did this routinely, that’s what I would do.
An end-note on cheap bearings
I’ve watched a lot of YouTube videos on this topic, and I’ve seen a lot of people do things to sealed bearings that they really shouldn’t. Take the seals off and grease them. Change just one of a pair of bearings, because only one was thoroughly worn out. Pop a bearing out of its fitting and put it back in the same fitting. I have also seen my wheelchair-using friend hesitate to change bearings, or wait until the bearings are obviously worn.
All of this arises, I think, from the notion that these bearings are somehow precious. If a set of bearings for your caster wheels is $40, you might think about taking some non-recommended steps to try to prolong their life.
And that, in turn, derives from the ludicrous prices charged for these commodity bearings by DME suppliers.
Hence the importance of the just-prior post.
You can easily buy commodity steel sealed bearings, in sizes to fit wheelchair fittings, for around $1 each. Sealed bearings are designed to be disposable. They are not designed to be serviced. And at $1 each, it’s no hardship to treat them as the disposables that they are.
This is Part 1 of a series of posts about replacing the fork bearings on a TiLite Aero wheelchair.
In this post, I only describe the “teardown” part of the process. That is, getting the forks off the chair. The removal and replacement of the bearings is for Part 2.
If you didn’t realize this repair might involve a complicated “teardown” step, and you were thinking of doing this repair yourself, then this post has done its job.
On this particular chair I ran into a worst-case scenario: The steel fork bearings had rusted solidly to the steel axles that they spin around. This stops you from removing the forks from the chair, which you need to do, in order to get to the fork bearings. Your choices are a) replace a few hundred dollars of wheelchair hardware, or b) break the bearings free from the steel axle that the bearing races are rusted to.
This step took several rounds of heating the axles with a propanetorch, spraying with lube, then pounding and prying until the rusted-on bearings broke loose.
Edit: You can see an alternative way to beat on the axle in this reference. There, the user removed the fork axle from its fitting first (i.e., took the fork axle off the wheelchair, fork and all), then beat the axle out of the fork. That’s a smarter approach than what I did. At the minimum, it shows that I’m not the only one have the problem of fork bearings that rusted solidly to the axle they sit on.
Other than spending a couple of hours doing that, the repair went smoothly.
The only practical takeaway isthat before you buy new bearings, bearing puller, bearing press, and so on — first try to remove your forks from the wheelchair.
If they come off readily — once you have removed any retaining hardware — move on to the next post,where I talk about options for replacement bearings, in some detail.
But if the forks don’t come off, even with a bit of lubricant and some gentle persuasion, then ponder just how hard you are willing to hammer on a wheelchair.
My lesson is that, even thought this repair eventually succeeded, I got lucky. With those fork bearing races rusted to the axle, it could just as easily have ended up with an unusable wheelchair, and a few hundred dollars plus a wait for replacement forks and fork axle assemblies.
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