Yes -- universal motors with a three-position switch, off, low, and high speeds (infinite series resistance, fixed series resistance, or zero series resistance -- for approximate values of infinite and zero. :-)
I have mine plugged into a speed controller for older (fixed speed) Dremels, and keep the motor switch set for "high". I had to replace the original switch on one at work when it started arcing when switched to "stop" once. :-) Mine survived nicely, so far. :-)
I've even used it, with one of the solid carbide bits made for printed circuit boards to drill out the center of a broken 6-32 tap.
Thanks for all the useful answers. I'm looking for examples of common produ cts which are currently in production, and where a risk of sudden failure e xists if the bearing fails to behave properly. Slow and lightly loaded appl ications aren't so interesting, as the design isn't critical and the price is going to be the main factor.
Car engines and jet engines are interesting. The last small engine I took a part (400 cc) had rolling element main bearings, whereas a similar older en gine (600 cc) had huge plain bearings and hardly any signs of wear. I also saw a compressor with a ball bearing in the big end of the connecting rod r ecently. This got me thinking. I don't see so many plain bearings in modern products, or at least nothing so visible as the bronze sleeves in my 1960s power hacksaw and 1940s sewing machine. But maybe "see" is the important w ord.
Can anyone tell me what kinds of bearings are used in specific car engines from well-known manufacturers today? Volkswagen, Ford, Mercedes, etc.? An e xample or two would be useful
I would guess that the small engine you took apart with rolling element bearings was a 2 stroke, that's pretty standard whereas a 4 stroke would be plain bearing. Regarding compressors rolling element bearings are simple and cheap and save having a pressure oil supply and can be splash lubricated so may be used where they can be fitted such as a single cylinder example a neighbour has or my 2 cylinder with 2 bearings on a common pin. A mate used to work for Bendix air compressors not many years ago and those compressors used plain bearing and the oil supply was taken off the engine so no need for an oil pump in the compressor. Another recent compressor I took apart had ball bearings for the main bearings on the crank and the big end bearings were plain supplied by a pick tube which dipped into the oil sump. One of the items my mate mentioned about the Bendix compressors was the conrods were aluminium and made from an alloy formulated by Rolls Royce IIRC around WW2 so the material properties suited the structural requirements of a conrod and acted as a bearing material also as the rod material acted as the plain bearing.
ducts which are currently in production, and where a risk of sudden failure exists if the bearing fails to behave properly. Slow and lightly loaded ap plications aren't so interesting, as the design isn't critical and the pric e is going to be the main factor.
apart (400 cc) had rolling element main bearings, whereas a similar older engine (600 cc) had huge plain bearings and hardly any signs of wear. I als o saw a compressor with a ball bearing in the big end of the connecting rod recently. This got me thinking. I don't see so many plain bearings in mode rn products, or at least nothing so visible as the bronze sleeves in my 196
0s power hacksaw and 1940s sewing machine. But maybe "see" is the important word.
s from well-known manufacturers today? Volkswagen, Ford, Mercedes, etc.? An example or two would be useful
Every make you mentioned uses plain shell bearings. Very few engines are bu ilt with roller crankshaft bearings today, and those are, as far as I know, all small, high-performance 2-strokes. Even they may have switched; I have n't kept up.
The advantages of roller bearings in an engine apply where there is little lubrication and high loads -- thus, the two-strokes. There were some roller
-bearing F1 4-strokes among the V10s (they were ceramic) but no longer.
The friction issue is about a wash overall in IC engines. One additional is sue with roller bearings is that they take up too much space in a compact e ngine crankcase.
Car engines and jet engines are interesting. The last small engine I took apart (400 cc) had rolling element main bearings, whereas a similar older engine (600 cc) had huge plain bearings and hardly any signs of wear. I also saw a compressor with a ball bearing in the big end of the connecting rod recently. This got me thinking. I don't see so many plain bearings in modern products, or at least nothing so visible as the bronze sleeves in my 1960s power hacksaw and 1940s sewing machine. But maybe "see" is the important word.
Can anyone tell me what kinds of bearings are used in specific car engines from well-known manufacturers today? Volkswagen, Ford, Mercedes, etc.? An example or two would be useful
Two strokes use rolling element bearings because at the speeds they operate at only a very small amount of lube is required. In fact, too much oil or oil pressure will cause the rolling elements to skid which leads to failure. As Ed says all major engine makers use plain bearings. Plain bearings can also be an advantage when the oil may be dirty. This is because, in part, the dirt particles either embed into the bearing material or are pushed out of the way. Rolling element bearings can be caused to skid on fine dirt particles. This of course leads to rapid bearing failure. Sometimes the dirt particles will get rolled over by the rolling elements and this distorts the bearing parts. This distortion can be elastic or plastic. Constant elastic distortion leads to premature failure from fatigue. Plastic distortion means that the bearing part is permanently distorted which also leads to rapid failure. Plain bearings can be made so that they will tolerate quite a bit of fine particle embedment without the particles acting as an abrasive. This is because the particles actually end up just beneath the bearing surface. Certain bearing materials, such as silver, have remarkable fatigue lives so they last a very long time. The above are just some of the reasons that plain bearings continue to be used in car engines, electric motors of all types, and even very heavy loaded shafting in hostile environments. With the materials used today plain bearings show exemplary lifetimes in demanding applications. A car engine today from any decent maker is expected to last at least 150,000 miles. At least. And this is in a situation where the user doesn't always change the oil as often as they should. And even though we tend to think of a bearing as something that rolls plain bearings can also be sliding. A great common example is a piston sliding up and down in a car engine. Failure of the bearing surface(s) in a cylinder will definitely lead to catastrophic failure. And it's not just the piston to cylinder bearing surfaces but also the piston ring to cylinder surfaces that need to work for a long time. I think you now have plenty of examples of common uses of plain bearings Chris, Eric
Honda runs camshafts directly in the aluminum of the cylinder head.
This was among the most thoroughly engineered, highest performance mass-produced engines of all time:
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"..Pratt deviated from its former design philosophy of rolling-element bearings and used plain silver-lead-indium bearings for the crankshaft main and master rod bearings."
Good article on the P&W 2800. Very good engine, but he neglected the engine analyzer distributor on the rear accessory gearbox in his listing of compo nents there. That was only the later models though. Everyone has their favo rite music, I reckon, but to an aircraft mechanic there's nothing more stir ring than four 2800's running dry on a 40 degree day at full throttle when all 4 water/meth. switches are thrown. Man, they could sing when the juice hit.
Am Freitag, 9. Dezember 2016 23:39:51 UTC+1 schrieb David Billington:
Actually, no. It was a 4-stroke JAP air-cooled engine and had taper-roller main bearings. Not such a new engine, I suppose, but much newer than the other engines I was working on at the time. It started me wondering if the change was part of a pattern.
e built with roller crankshaft bearings today, and those are, as far as I k now, all small, high-performance 2-strokes. Even they may have switched; I haven't kept up.
interested to know.
Jim gave a link to a bearing manufacturer or something a few posts up the t hread. It does a good job of telling what they're using today, and why.
There are two basic kinds: two-layer (steel shell, silicon-aluminum bearing face) and three-layer (high-performance, steel shell, several other metals used in layers.) I've also heard of silver being used as the top layer in racing engines -- extreme resistance to fatigue.
Quite a few use aluminum alloy bearings - some on steel backs. Some use the same tri-metal bearings used in 50s and 60s cars - steel , copper, and "babbit" type bearing surface.
Quite a few Honda GX50 and GX25 engines and clones are double ball bearing cranks.
Jim gave a link to a bearing manufacturer or something a few posts up the thread. It does a good job of telling what they're using today, and why.
There are two basic kinds: two-layer (steel shell, silicon-aluminum bearing face) and three-layer (high-performance, steel shell, several other metals used in layers.) I've also heard of silver being used as the top layer in racing engines -- extreme resistance to fatigue.
Good luck with that; if all else fails, though, recall that bicycles with common ball bearings and waterproof grease last a long time, even here in rainy Seattle. I made an SS cone to rebuild one, and did not like the results. I was young and ignorant enough to just use a scrap of some anonymous SS, but the failure was memorable: it didn't gall, it shredded.
What was the original engine size in the '53 TD? The MGA came with 1498 CC, 1598 CC, and 1622 CC IIRC. I understand that the 1498 was to avoid a punitive tax on engines larger than 1500 CC in the UK at that time. :-)
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