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Post by c64 on Nov 21, 2012 23:32:49 GMT
I know that learning to ride a bile is hard. My dad once said that after my first time I used my bicycle alone (I never had training wheels), I came home and told my parents that the big green hedge at the foot of the steep slope of our road is red inside and has thorns. Is gear crunching likely or even possible (unless you drive a non-synchromeshed vehicle)? Yes and no! In a common transmission, all gears are "in" all the time, they are always connected to each other and can't grind. In an automatic transmission, there are clutches which connect them to the next set of gears or the output shaft. The torque converter makes sure the clutches don't really grind when activated and you can stop with a gear in and start driving without grinding those clutches. The gearbox is lubed with a special thin oil which is also pressurized and used for the hydraulic actuators which operate the clutches. In a manual transmission, it's different. Here, one shaft rotates with 3,4,5 or 6 gears attached to it in a row driven by the engine. Above are the counterparts of those gears but they are not fixed to the shaft, they can spin free on the shaft which is the output shaft. The trick is that between every two of them is a mechanism which connects the gears to the shaft, this is the forward/backward action of the stick. Which set of couplers connected to this action is determined by the left/right action of the stick. The gearbox is filled with a very thick oil. When you push the stick, a radial grooved disc is pressed near the gear you want to connect to the output shaft. The gears churn oil almost like a torque converter and make the grooved discs spin. There is a tricky mechanism which locks the stick so you can't press any further until the speed of the gear and the disc roughly matches and have the right phase to each other. Then you can push further and clamps (called dog ears) move into holes in the gears fixing the gear to the shaft. When the system fails to sync but also fails to lock because the speed is roughly matching but won't keep in phase due to a broken clutch or the clutch wasn't used properly, the "dog ears" try to enter the holes in the gear but bounce off which causes this rattling "grinding" sound. It's not the teeth of the gears which grind! The only gear which might grind depending on the gearbox design is the reverse gear where the teeth of two gears are kept seperate until you switch to "R" connecting them. A good clue is if the Reverse gear faces a forward gear (then it is likely to have dog ears like a regular gear) or not (seperate mechanism): Facing Not facing: 1–3–5 R–1–3–5 2–4–R ... 3–4 |
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Post by c64 on Nov 21, 2012 23:45:54 GMT
There are 3 kinds of manual transmissions.
Non synchronized, just the dog ears pushed and pulled by the stick.
Synchronized, it has the discs which speed up or slow down the gear. Here you push/pull the stick to engage the synchronizing process and you need to feel by the vibrations if the gear has the correct speed or not. Then you can push/pull further to engage the dog ears.
Lock synchronized, here is a very clever piece of mechanics in between which senses if the gear has the correct speed and phase until it allows the dog ears to move into the gear. This is the standard for cars for about 50 years.
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Post by c64 on Nov 21, 2012 23:48:26 GMT
In Reality there are no 3 different rods used. It's one rod but the stick turns it when moved left and right. The angle of this rod determines which set of couplers is used. The forward/Backwards action of the stick moves this rod and moves the coupler designated to the current angle.
This also prevents that you can engage two couplers at the same time which would lock the gearbox and destroy it.
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Post by c64 on Nov 21, 2012 23:52:43 GMT
The only gear which might grind depending on the gearbox design is the reverse gear where the teeth of two gears are kept seperate until you switch to "R" connecting them. A good clue is if the Reverse gear faces a forward gear (then it is likely to have dog ears like a regular gear) or not (seperate mechanism): You can sometimes end up grinding the gears on a manual transmission if you accidentally skip a gear when changing down - I've done this a few times by accidentally shifting down from fourth to first gear. (No excuses, I just messed up a couple of times when driving. It happens *shrugs*). I've also done this by either not fully releasing the clutch, or releasing it at the wrong moment. In any case my point was really that putting people who've never used a manual transmission before into such a car does have the potential for some humorous footage, without the risk of bodily harm falling off a bike would entail. You didn't grind the gears, you simply can't. You ground the dog ears which tried to connect the gears to the output shaft! |
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Post by KMCCLA on Nov 22, 2012 2:15:41 GMT
I do that all the time. Mostly from 3rd, 4th, to 5th, but I once went from 2nd to 5th. I learned on, and my first four cars where all manual, then I got an automatic, then back to a five speed. It had been several years since I had driven a stick, but it all came back like nothing had happened. To me it seems to be second nature, and shift without even thinking. Every now and then my gears "rattle" (grinding noise) when I but into reverse, or into 1st, and it is standing still. |
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Post by the light works on Nov 22, 2012 18:12:45 GMT
That's because reverse and first don't have the synchromesh components, and if the clutch isn't completely disengaged, the input geartrain still rotates.
my old fire tender was unsynchronized, and I was the quickest driver in the department - mainly because I was the only one who had the right combination of learning shifting from my dad, and the correct attitude to shift it without pedaling it like a bicycle. on a hot run, the only noise from the transmission was the sound of the shift lever hitting the side of my seat when I threw it from 6L to 1H
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Post by silverdragon on Nov 23, 2012 8:57:27 GMT
How about trying to get ME to drive to "Test standard"?......
I passed a car test many years ago, but have since got bigger licences, now it seems logical that by driving Larger more complicated vehicles, I should blow through a car licence with out even blinking?....
Over-use of mirrors, Block changing, clutch-less changes, crossing hands on the wheels, not stopping fully at stop signs if there is no good reason to, being too far from the kerb at times, crossing the bit-of-paint, (Its ONLY a bit of paint... if there is nowt coming get over and use the road....) reversing fully on mirrors without looking over the shoulder, in some vehicles, using Gears to slow down rather than brakes, ...... I could go on, but any number of those could get me a few negative marks on a test?....
Reversing... unless I KNOW the loading bay, I will walk the course first.
I do not do blind reverses without a good look-see first.
I can roll to a stop at a set of lights without even using the brakes from 30 mph.
I do that frequently if the conditions are right... its a little practise for times when you may need to stop without brakes.....
My favourite DEFINITE fail would be me trying to pass a test in an Automatic... without bad language?... not happening, even WITH bad language allowed, I am still going to torture the gear box eventually....
Just HOW do you do the stop without brakes when the gearbox wont allow a forced downshift?....
Riding a Bike?... thats easy compared with ME driving to car-test standard.
I was once told that with the HGV test if I ever had to take a Car test again, I must warn them first, otherwise Its a guaranteed fail because of "advanced" techniques, especially Hazard Perception that some car test examiners may see as "Over cautious"....
So does some of the above make me a Bad driver?...
Possibly?...
I also got a few bad habits... like keeping the hand on the gear-stick between changes...
Driving a little wide in the lane to see past the queue of traffic I am following....
Over-anticipating a set of lights that I know are about to change away from green, as in I know I wont get there on before they change so start slowing down early.
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Post by silverdragon on Nov 23, 2012 9:01:43 GMT
TLW, what, you dont know how to alter the changer to match the gears?.....
Ride a bike... I would get shouted at for doing it my way, which is the "No hands" approach... I know the right wires to pull to work the brakes?....
Look Mum, No Hand....
Closely followed by
Look Mum, No Teef......
Is riding half a mile on one wheel considered good or bad?... I had a front puncture and couldnt be bothered fixing it roadside, so rode home on the back wheel only.
I USED to be able to ride a bike backwards as well....
I dont think I can remember how to do that now?...
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Post by c64 on Nov 23, 2012 15:11:55 GMT
I passed a car test many years ago, but have since got bigger licences, now it seems logical that by driving Larger more complicated vehicles, I should blow through a car licence with out even blinking?.... I recently did just that. A friend needs every license for his job he is training for. They gave him a PC program for the theoretical test and I checked it out. I passed all licenses easily with almost no errors - even the motorcycle stuff I never had before. For the practical test, I once had a guy who did practical driver's license tests as his job and he said that he wouldn't give me a license if this was driving school. Well might be caused by the road which was in a river valley and which looked like "Test Drive I", lots of slopes, twists, hairpin corners - in summary it was touring car's heaven. |
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Post by the light works on Nov 23, 2012 15:18:54 GMT
TLW, what, you dont know how to alter the changer to match the gears?..... ?? clarify please? |
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Post by silverdragon on Nov 24, 2012 8:33:40 GMT
TLW, By Deralleur gears, I presuming you refer to the two cogs hanging under the main block that guide the chain..
To match those to the shifter, the one on the handlebars that clicks when you change gears, and to set it up to select the right gear...
Presuming you have not changed the main block, or the spacing between those cogs on that block, which is entirely possible but advanced tinkering that would need a new gear selector anyway.....
Otherwise, once you have one gear right, the selector SHOULD automatically have all the others right... the spacing hasnt changed....
So this is how you should be able to get that set.
I have put in as much detail as I think relevant as I dont know the readers level of push-bike tinkering skills?.... so sorry if some of it is teaching Grandma to suck eggs....
Move the selector to "Top" gear so the wire is loose, or at it loosest...
There should be a semi-adjuster screw on the handlebar selector body where the wire enters the unit, screw that IN to get more slack on the wire.
There may also be one on the Derailleur unit, on some models, lucky you if you have that, also slacken that screw.
"Advanced" technique here is to tighten those one turn or two just in case you get the wire too tight.... ?..
At the derailleur end, loosen the screw that holds the gear change wire, and pull the wire through so its just about tight, then tighten the bolt up again, you dont have to be too exact as you have that semi-adjust on the handlebars?... and, if you have it, the one on the derailleur...
Get the wire tight enough at the dérailleur end that its just about holding the top gear.
There should be two screws on the body of the deralleur that limit its travel, you may need to undo the one that stops the chain going past top gear slightly to get this done, dont forget to tighten it again when you finish....
I admit this is slightly fiddly, and you may end up wondering of you need three hands to do all this, I have found a pair of Mole grips on the wire to stop the wire going back through that retaining clip works wonders as a third hand?....
I have also found that the mole-grip holding the wire can be used as a temporary hold to test the gear selection process...
Just be wary of its position if the wheel is spinning?... mole grips into spokes can be expensive.... re-spoking a wheel is extremely "advanced" fiddly sweary time consumingly stressfully annoying.
Tighten up the wire retaining bolt/screw again, then test the selector lever between top and the next cog down.
If the wire is too loose, use the semi-adjust on the selector to tighten it slightly....
That SHOULD have matched your selector lever to the dérailleur ..... again, check those two screws on the body of the dérailleur that limit its travel, as the one that stops the thing choosing to go off 1st gear into the wheel and mangle the spokes is probably the one that causes most incidents of dérailleur malfunction....
This whole help guide is from Memory, so if I missed something, just ask...
...as its something I have done a few times... the only thing on Bikes I CANT do without getting the manual out is the inside of a Sturmey-Archer three-speed Hub....
Push bikes are something of s speciality to me, I was well known as a Kid as the local bike mechanic.
The same process is exactly the same for the Front cog section on those that have multiple front cogs and derailleur there.
If this was useful, let me know, if its wrong, ALSO let me know....
Please also note, if the wire is changed, you may have to tighten it up again after a couple of weeks use as wires stretch.
You may also find that you have to repeat the process if the Wheel is taken off... sometimes the wheel does not sit exactly the same when you put it back on.
The semi-adjusts can handle most of that.
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Post by silverdragon on Nov 24, 2012 9:14:29 GMT
In the HGV Theory test, they had to "Reset" the Hazard perception test computer... I "broke" it?....
Apparently you are only supposed to see ONE hazard per scene?...
I was clicking away merrily at all possible hazards until the examiner came over and explained....
The whole theory test, for HGV C+E, class 1 on old money, the final test, I got 100%, and so I bloody well SHOULD have, I have been driving that many years and supposed to have that much experience, If I dont know what that common road sign is supposed to be saying, I should hand back my licence?....
On my Road test, I got an examiner who "Knew" me, he said he would be fair, but as it was me, he would take me places that would test my absolute limit of skill... as in, he took me to the start of a 1-in-4 (25%) Grade on a wet day and made me do a hill start to see if I would spin out because the trailer was empty and had no weight on the drive wheels....
Extreme Hill Starts... a 25% hill or steeper on wet shiny tarmac. three partial spins, as I tried to change up the gears, I adapted my driving, stuck it back in crawler and just went up slowly....
"Thats a pass on that one then... you know I passed one guy who just backed down to the bottom to get a run up?... there is no law against driving slowly, but I never saw anyone yet who didnt actually stop more than once trying that...."
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Post by the light works on Nov 24, 2012 13:27:04 GMT
"TLW, By Deralleur gears, I presuming you refer to the two cogs hanging under the main block that guide the chain..
To match those to the shifter, the one on the handlebars that clicks when you change gears, and to set it up to select the right gear...
"
I think it was a 6 speed gearset with a 5 speed deurailler. it would shift fine in the lowest gears and the highest gears, and put the chain exactly between anything in the middle. - that or it shifted just a little wide and averaged out at the other end of the travel.
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Post by silverdragon on Nov 26, 2012 7:44:11 GMT
Strange,,, Dérailleurs dont do X-Number of gears "only".... its only the two screws on the body that limit its travel, so one from a 5-speed set should work just fine on a 6 speed set.
I know the spacing may have changed, but, I suggest that those two screws are limiting the travel, thus creating a narrower gap on the top two and bottom two gears, which is why they worked "Better"... it kind of explains its self when you think of having its travel limited at top and bottom?...
I therefore suggest your derailleur wasnt set to cover the full range of gears?...
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Post by the light works on Nov 27, 2012 15:51:44 GMT
Strange,,, Dérailleurs dont do X-Number of gears "only".... its only the two screws on the body that limit its travel, so one from a 5-speed set should work just fine on a 6 speed set. I know the spacing may have changed, but, I suggest that those two screws are limiting the travel, thus creating a narrower gap on the top two and bottom two gears, which is why they worked "Better"... it kind of explains its self when you think of having its travel limited at top and bottom?... I therefore suggest your derailleur wasnt set to cover the full range of gears?... that is only the case if you have a non-indexed shift controller. in my case, the cogs on the gearset were, say (I don't have the bicycle here to measure it) .25 inches on center. every time I struck a shift key, it moved the deurailler .3 inches. it's the same as putting an Allison shift linkage into a Tremec gearbox - the hardware won't line up properly. |
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Post by silverdragon on Nov 29, 2012 9:11:26 GMT
It was my understanding, and always has been in practise, if you change the derailleur the new one will be set to do exactly the same as the old one, and move exactly the same space between gears, not because of the Index shift controller problem, but because even with a straight lever, the space between cogs will always be the same regardless of derailleur set....
Its also common that people will change the derailleur set, either for a better one or one that hasnt ended up mangled in the wheel replacement?....
So saying that, the only thing that would change the distance a derailleur would move between gears would either be a change of index handlebar shifter or manually changing the spacers between the cogs on the actual wheel?....
Index shifter sets can come with different spacings between gears because some people like to add/change/replace cogs, but you only have so much room, so the usual difference is how many gears you have within that certain space, as a seven speed gear block must fit in the same space as a 5 speed block, so with a seven speed block you use thinner spacers between the cogs....
On that score, I am suggesting that a seven speed block will often measure the same distance between 1st and 7th as the distance between 1st and 5th on a 5 speed block.
After that, when you get to wheels for certain high end tinkerers that can fit say 9 cogs because they move the spokes over to make more space, and indexing sets where you can manually change the spacing between the index "clicks", you are getting into "EXPENSIVE" Territory, advanced tinkering, and it all becomes technical......
So much so that those that use the high number of cogs on a rear block tend to go for NON indexed gear changes, and do it "The old way", "Feel" for the gear.....
Again, I must ask, was it JUST the derailleur set that you changed on the bike?...
As Far as I am aware, well, certainly over this side of the pond, it should make no difference, Shimano or Campagnolo (just two manufacturers from a long list, (spelling approximate)) should be interchangeable....
Either way, you have given me a "Head scratcher", and an advanced tinkering challenge that if I lived nearer, I would be curious to investigate.............
Especially if they are working on the same gear block...
HOWEVER....
Newtons law of levers.
The way the Wire is attached to the derailleur set....
If for instance the wire goes to the top of the clip (on the derailleur) (when bike upside down) rather than the bottom, it may extend (slightly) the length of the "lever" that is changing the gear?....
I have known someone who had a slight problem with the shifter being "Out of sync" with gears because the wire was fouling on something and coming off the derailleur at the wrong angle.
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Post by the light works on Nov 29, 2012 15:23:33 GMT
"It was my understanding, and always has been in practise, if you change the derailleur the new one will be set to do exactly the same as the old one, and move exactly the same space between gears, not because of the Index shift controller problem, but because even with a straight lever, the space between cogs will always be the same regardless of derailleur set...."
well, THERE'S your problem.
the first bike shop installed a deurailler that was NOT matched to the indexed shifter; and obviously didn't test ride the bike to be sure it worked.
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Post by silverdragon on Nov 30, 2012 7:50:53 GMT
They didnt test it?....
Now that is a shop to avoid.
Electricians first rule, Is it Plugged In covers a multitude of sins, and you always turn it on to make sure its working when you finished?... its not like you replace a bulb and dont switch it on to make sure its not a dud?...
Bike repairs, if you fix it, TEST it...
How hard is it to turn the pedals and check its changing gear?......
Incredulous that anyone could be that professionally stupid
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Post by the light works on Nov 30, 2012 15:45:18 GMT
now you know the basis of my username.
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Is gear crunching likely or even possible (unless you drive a non-synchromeshed vehicle)?
