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Post by GTCGreg on Dec 13, 2017 16:19:30 GMT
spongebob doesn't have ABS. ABS=Antilock Breaking System. Can you lock up the brakes on Spongebob? |
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Post by the light works on Dec 13, 2017 16:28:22 GMT
spongebob doesn't have ABS. ABS=Antilock Breaking System. Can you lock up the brakes on Spongebob? yes, I managed to skid a wheel, once. |
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Post by silverdragon on Dec 14, 2017 6:21:33 GMT
View Attachmentthis is the sort of thing we get over here. so you know what you are looking at, this was the crash we had last year, where the sanding truck escorted me in. the cleat marks are from the chains on the sanding truck, and the tire marks are from backing the engine into a driveway to turn it around. this was also the incident where the safety officer wanted me to reposition the engine three times. "stop" consisted of taking the truck out of gear and hoping it wasn't on a downgrade. - or, in the driveway, shifting to drive to get it going forwards instead of backwards. So what you are saying is that the fire engine has no effective brakes?.. And you still drive it?. Excuse me whilst I need to be elsewhere?. I have driven one vehicle with no brakes, except hand brake, and that was a 6ton crane we used to use at the boat factory, but as it never got above 2mph, and the handbrake could lock all four wheels at that speed, nay mither... However, take it out the yard on a road?.. yer kidding me yeah?. |
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Post by the light works on Dec 14, 2017 14:57:47 GMT
View Attachmentthis is the sort of thing we get over here. so you know what you are looking at, this was the crash we had last year, where the sanding truck escorted me in. the cleat marks are from the chains on the sanding truck, and the tire marks are from backing the engine into a driveway to turn it around. this was also the incident where the safety officer wanted me to reposition the engine three times. "stop" consisted of taking the truck out of gear and hoping it wasn't on a downgrade. - or, in the driveway, shifting to drive to get it going forwards instead of backwards. So what you are saying is that the fire engine has no effective brakes?.. And you still drive it?. Excuse me whilst I need to be elsewhere?. I have driven one vehicle with no brakes, except hand brake, and that was a 6ton crane we used to use at the boat factory, but as it never got above 2mph, and the handbrake could lock all four wheels at that speed, nay mither... However, take it out the yard on a road?.. yer kidding me yeah?. look again at the character of the tire marks in the picture. note especially that the grit didn't leave any scratches in the skid marks. the ice was a perfect combination of hard and slick that morning. |
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Post by silverdragon on Dec 16, 2017 8:44:29 GMT
So what you are saying is that the fire engine has no effective brakes?.. And you still drive it?. Excuse me whilst I need to be elsewhere?. I have driven one vehicle with no brakes, except hand brake, and that was a 6ton crane we used to use at the boat factory, but as it never got above 2mph, and the handbrake could lock all four wheels at that speed, nay mither... However, take it out the yard on a road?.. yer kidding me yeah?. look again at the character of the tire marks in the picture. note especially that the grit didn't leave any scratches in the skid marks. the ice was a perfect combination of hard and slick that morning. You may have to excuse me for being denser than the sheet of ice they drive over on IRT here, but, are you saying the brakes work too well, not at all, all at once, or?... Air brakes, especially on early trucks, had woefully less feel that trying to pick up a screw with three pairs of gardening gloves. All you could feel was the spring that was four times its needed strength in order to stop you riding the brakes?. You know your breaking something when your nose touches the window... Since that time, you nose no longer touches the window, because they started mandatory fitting of Seat Belts. But the brakes now have some form of !"feel", or maybe it is that in all that time I have got a bit more sensitive to them?.. Yes I know your fire engines are a bit lacking, mostly built on frames designed for farm trucks, and brakes smaller in disc size than a Mini, some may even still be running drums, but, that frame wasnt designed to hold how-many-gallons-of-water plus up to half a dozen santa sized firemen fully kitted with all their gear. Is it just a case of the brakes are undersized for that weight of truck?. [IRT, Ice Road Truckers] |
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Post by the light works on Dec 16, 2017 9:51:01 GMT
look again at the character of the tire marks in the picture. note especially that the grit didn't leave any scratches in the skid marks. the ice was a perfect combination of hard and slick that morning. You may have to excuse me for being denser than the sheet of ice they drive over on IRT here, but, are you saying the brakes work too well, not at all, all at once, or?... Air brakes, especially on early trucks, had woefully less feel that trying to pick up a screw with three pairs of gardening gloves. All you could feel was the spring that was four times its needed strength in order to stop you riding the brakes?. You know your breaking something when your nose touches the window... Since that time, you nose no longer touches the window, because they started mandatory fitting of Seat Belts. But the brakes now have some form of !"feel", or maybe it is that in all that time I have got a bit more sensitive to them?.. Yes I know your fire engines are a bit lacking, mostly built on frames designed for farm trucks, and brakes smaller in disc size than a Mini, some may even still be running drums, but, that frame wasnt designed to hold how-many-gallons-of-water plus up to half a dozen santa sized firemen fully kitted with all their gear. Is it just a case of the brakes are undersized for that weight of truck?. [IRT, Ice Road Truckers] brake bias = 60/40% to the front, plus allison automatic shift transmissions over four tires in the back and two in the front = more thrust on the rear than grip on the front addendum: now that I have time to finish my post, it means that trying to stop at maneuvering speed locks the front before it overrides the torque converter, so trying to stop in gear means you drift towards the ditch - and not in the fun way. |
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Post by silverdragon on Dec 16, 2017 10:10:47 GMT
Nope, still not seeing more than mist on a foggy day...
So its six wheel drive?.. automatic six wheel drive with a brake bias to the front tyres that doesnt change with load sensors.
I am guessing that this means you will straight-line a corner because the front tyres dont grip under braking?.
Am I getting somewhere with this?.
And by the way, thats no more than we already believe of USA vehicles, that they cant handle corners, and although mystified by TG, this is a general expectation, not helped by the cars from USA that have been bought over here that have a turning circle of a good sized cross channel ferry?.
For me, what you are describing, is a vehicle that almost demands retrofitting of ABS, with the addition of a system that automatically senses which tyre has most grip and send the braking to that tyre/those tyres until it changes.
Most HGV's in UK have auto-brake bias that has load sensing inbuilt.
Well, most of what I have driven recently [last two decades] anyway?.
As the back suspension rises under braking, the brake bias is thrown "forwards"...
BTW, just noted the bit about more thrus on the rear than grip on the front in Automatic...
does that mean that under sudden braking, the rear wheels may be still being driven by the transmission until the engine stops "driving", as in a noticeable lag of loss of power between taking foot off drive and onto brake?.
If so, you just sounded one of the major bongs of the bells of doom that I have always held for Automatic transmission...
In UK, if you take foot off power and dont hit the clutch, the engine automatically stops using fuel, and starts becoming a bloody big Anchor, engine braking, and with either good gear juggling [-stirring porridge] or modern semi-automatics, dropping a cog will increase engine braking, thus extra braking when your discs start to glow a little.
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Post by the light works on Dec 16, 2017 12:06:01 GMT
Nope, still not seeing more than mist on a foggy day... So its six wheel drive?.. automatic six wheel drive with a brake bias to the front tyres that doesnt change with load sensors. I am guessing that this means you will straight-line a corner because the front tyres dont grip under braking?. Am I getting somewhere with this?. And by the way, thats no more than we already believe of USA vehicles, that they cant handle corners, and although mystified by TG, this is a general expectation, not helped by the cars from USA that have been bought over here that have a turning circle of a good sized cross channel ferry?. For me, what you are describing, is a vehicle that almost demands retrofitting of ABS, with the addition of a system that automatically senses which tyre has most grip and send the braking to that tyre/those tyres until it changes. Most HGV's in UK have auto-brake bias that has load sensing inbuilt. Well, most of what I have driven recently [last two decades] anyway?. As the back suspension rises under braking, the brake bias is thrown "forwards"... BTW, just noted the bit about more thrus on the rear than grip on the front in Automatic... does that mean that under sudden braking, the rear wheels may be still being driven by the transmission until the engine stops "driving", as in a noticeable lag of loss of power between taking foot off drive and onto brake?. If so, you just sounded one of the major bongs of the bells of doom that I have always held for Automatic transmission... In UK, if you take foot off power and dont hit the clutch, the engine automatically stops using fuel, and starts becoming a bloody big Anchor, engine braking, and with either good gear juggling [-stirring porridge] or modern semi-automatics, dropping a cog will increase engine braking, thus extra braking when your discs start to glow a little. it's four wheel drive: them four in back. and ABS would do nothing because ABS shuts down at speeds that slow. load sensing does nothing because there is not enough weight shift to register. in proper driving conditions, especially if you have good enough road to have the jake enabled, as soon as you step off, it starts dragging its feet, and in fact, with practice, you learn to feather the throttle to control whether you coast or turn on the jake. but that original post is a comment on how snotty our roads get when we do have a black ice day. |
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Post by silverdragon on Dec 17, 2017 14:53:21 GMT
Ahh right, the fog is clearing.
This is why the Jake or exhaust brake used to be a pedal extra on the floor, or at least a foot operated push button, so you can choose when and where to use it?.
Having it as a switch on the dash that just triggers it as soon as you come off the power, sometimes you forget to turn it off?.
Add to that a automatic transmission, I can see your problems.
Sometimes you need to coast a corner, neither power or brakes, or just a light touch of brake as almost a trail brake... and ability to left foot brake whilst gently coming off the power...
This is again why I do prefer a full manual, it does give you more control.
Especially in tricky conditions.
The extra foot work is not that hard to learn, is it?.
Also having four HUGE tyres or double tyres [8 tyres in all] trying to straight line you at the back and two skinny gits at the front not quite able to change directions... hmm... been there, hate that.
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Post by the light works on Dec 17, 2017 16:31:48 GMT
Ahh right, the fog is clearing. This is why the Jake or exhaust brake used to be a pedal extra on the floor, or at least a foot operated push button, so you can choose when and where to use it?. Having it as a switch on the dash that just triggers it as soon as you come off the power, sometimes you forget to turn it off?. Add to that a automatic transmission, I can see your problems. Sometimes you need to coast a corner, neither power or brakes, or just a light touch of brake as almost a trail brake... and ability to left foot brake whilst gently coming off the power... This is again why I do prefer a full manual, it does give you more control. Especially in tricky conditions. The extra foot work is not that hard to learn, is it?. Also having four HUGE tyres or double tyres [8 tyres in all] trying to straight line you at the back and two skinny gits at the front not quite able to change directions... hmm... been there, hate that. I can do both, but it's really not that hard to learn to feather the throttle properly. it's just a difference between resting your foot and lifting off. - and if you expect bad weather you just disable the jake. the new rigs even light the brake lights when the jake activates. of course, none of our rigs have unmuffled jakes - and most of the new ones have either exhaust restrictors or transmission retarders instead of the actual Jacobs system. but we really don't have an understeer problem in normal driving. at least not in the new rigs. the old homemade tenders could get a little light on the front end on upgrades or under heavy acceleration.  my understanding is there was another rig with the same wheelbase but with the tank pushed a foot further back for a cabinet behind the cab. |
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Post by silverdragon on Dec 18, 2017 7:27:08 GMT
Need to learn a little more here about "Jacobs system", un-muffled and muffled exhaust brakes, we dont get the Un muffled ones here this side of the pond.
I am goina have to do some duck-fu on Jacobs.
I know how it works from the cab, but not the how it works under the hood?.. well, not properly anyway?.
Will write in again when I do.
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Post by the light works on Dec 18, 2017 15:16:23 GMT
Need to learn a little more here about "Jacobs system", un-muffled and muffled exhaust brakes, we dont get the Un muffled ones here this side of the pond. I am goina have to do some duck-fu on Jacobs. I know how it works from the cab, but not the how it works under the hood?.. well, not properly anyway?. Will write in again when I do. pretty straight forward system: there is an extra set of valves in the head. piston hits TDC and it pops the valve open to dump the compression. comparing to an exhaust brake - that diverts the exhaust into a pressure chamber. option three is a tranny retarder - which engages a torque converter that is bolted down so the output can't turn. |
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Post by silverdragon on Dec 19, 2017 7:38:02 GMT
Need to learn a little more here about "Jacobs system", un-muffled and muffled exhaust brakes, we dont get the Un muffled ones here this side of the pond. I am goina have to do some duck-fu on Jacobs. I know how it works from the cab, but not the how it works under the hood?.. well, not properly anyway?. Will write in again when I do. pretty straight forward system: there is an extra set of valves in the head. piston hits TDC and it pops the valve open to dump the compression. comparing to an exhaust brake - that diverts the exhaust into a pressure chamber. option three is a tranny retarder - which engages a torque converter that is bolted down so the output can't turn. The exhaust system into a pressurised chamber that creates a back pressure adding even more stopping power that has a slow leak into the exhaust stacks makes more sense?.. just venting it to air with no exhaust muffle is the reason why many towns and cities have banned "jake brake" during certain hours, because of the noise, and I know they are that noisy. I would have thought a retro-fit of a set of headers from the Jake output into an exhaust muffler wouldnt be that hard to do, thus you can use the Jake during all working hours?. Or is that me oversimplifying the problem here?. The reason for exhaust brake is simple, it provides braking without using the normal brake system, which tends to overeat with excessive use. "There must be a better way"... |
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Post by GTCGreg on Dec 19, 2017 15:07:12 GMT
pretty straight forward system: there is an extra set of valves in the head. piston hits TDC and it pops the valve open to dump the compression. comparing to an exhaust brake - that diverts the exhaust into a pressure chamber. option three is a tranny retarder - which engages a torque converter that is bolted down so the output can't turn. The exhaust system into a pressurised chamber that creates a back pressure adding even more stopping power that has a slow leak into the exhaust stacks makes more sense?.. just venting it to air with no exhaust muffle is the reason why many towns and cities have banned "jake brake" during certain hours, because of the noise, and I know they are that noisy. I would have thought a retro-fit of a set of headers from the Jake output into an exhaust muffler wouldnt be that hard to do, thus you can use the Jake during all working hours?. Or is that me oversimplifying the problem here?. The reason for exhaust brake is simple, it provides braking without using the normal brake system, which tends to overeat with excessive use. "There must be a better way"... The better way is electric hybrid. You use regenerative braking to store the braking energy and reuse it to get moving again. Could such a regenerative system be designed using compressed air? |
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Post by the light works on Dec 19, 2017 15:43:35 GMT
pretty straight forward system: there is an extra set of valves in the head. piston hits TDC and it pops the valve open to dump the compression. comparing to an exhaust brake - that diverts the exhaust into a pressure chamber. option three is a tranny retarder - which engages a torque converter that is bolted down so the output can't turn. The exhaust system into a pressurised chamber that creates a back pressure adding even more stopping power that has a slow leak into the exhaust stacks makes more sense?.. just venting it to air with no exhaust muffle is the reason why many towns and cities have banned "jake brake" during certain hours, because of the noise, and I know they are that noisy. I would have thought a retro-fit of a set of headers from the Jake output into an exhaust muffler wouldnt be that hard to do, thus you can use the Jake during all working hours?. Or is that me oversimplifying the problem here?. The reason for exhaust brake is simple, it provides braking without using the normal brake system, which tends to overeat with excessive use. "There must be a better way"... most modern jake brakes run through the exhaust system, including the mufflers. at this point, the only reason for an unmuffled jake is if the driver wants to make noise. in fact, I think the two new engines do use a newest generation jake. they have a distinctive rattle when they come to a stop, but otherwise, there isn't much difference in sound. I think the rattle comes from giving the engine a bit of fuel to keep it turning when the torque converter releases. |
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Post by the light works on Dec 19, 2017 15:48:05 GMT
The exhaust system into a pressurised chamber that creates a back pressure adding even more stopping power that has a slow leak into the exhaust stacks makes more sense?.. just venting it to air with no exhaust muffle is the reason why many towns and cities have banned "jake brake" during certain hours, because of the noise, and I know they are that noisy. I would have thought a retro-fit of a set of headers from the Jake output into an exhaust muffler wouldnt be that hard to do, thus you can use the Jake during all working hours?. Or is that me oversimplifying the problem here?. The reason for exhaust brake is simple, it provides braking without using the normal brake system, which tends to overeat with excessive use. "There must be a better way"... The better way is electric hybrid. You use regenerative braking to store the braking energy and reuse it to get moving again. Could such a regenerative system be designed using compressed air? abut ten years ago, UPS commissioned a fleet with a hydraulic hybrid system. some old trucks do have a compressed air starting system, but I think a compressed air hybrid system would not be as easy to make as other systems. - part of that would be the noise involved. since compressed air power systems vent to atmosphere, and muffling them affects their output, imagine your truck sounding like an oversized air wrench every time you accelerate. - on the trucks I've heard use an air starter, the starter is louder than the engine. |
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Post by GTCGreg on Dec 19, 2017 16:45:56 GMT
The better way is electric hybrid. You use regenerative braking to store the braking energy and reuse it to get moving again. Could such a regenerative system be designed using compressed air? abut ten years ago, UPS commissioned a fleet with a hydraulic hybrid system. some old trucks do have a compressed air starting system, but I think a compressed air hybrid system would not be as easy to make as other systems. - part of that would be the noise involved. since compressed air power systems vent to atmosphere, and muffling them affects their output, imagine your truck sounding like an oversized air wrench every time you accelerate. - on the trucks I've heard use an air starter, the starter is louder than the engine. Just a few brain farts. It would have to be an entirely redesigned engine, but maybe use some of the cylinders to accommodate air assist. By using another set of valves and disabling the injectors on some of the cylinders, you should be able to do that. The air exhaust would still be through the existing muffler system. You should be able to also use those same cylinders as the air compressor during breaking to pressurize the regenerative braking air tank. |
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Post by the light works on Dec 19, 2017 17:44:06 GMT
abut ten years ago, UPS commissioned a fleet with a hydraulic hybrid system. some old trucks do have a compressed air starting system, but I think a compressed air hybrid system would not be as easy to make as other systems. - part of that would be the noise involved. since compressed air power systems vent to atmosphere, and muffling them affects their output, imagine your truck sounding like an oversized air wrench every time you accelerate. - on the trucks I've heard use an air starter, the starter is louder than the engine. Just a few brain farts. It would have to be an entirely redesigned engine, but maybe use some of the cylinders to accommodate air assist. By using another set of valves and disabling the injectors on some of the cylinders, you should be able to do that. The air exhaust would still be through the existing muffler system. You should be able to also use those same cylinders as the air compressor during breaking to pressurize the regenerative braking air tank. so you basically have your engine driving an air compressor. the valving operates to select between neutral, increasing pressure, or pressure driven. perhaps you could also divert exhaust into the pressure reservoir. a couple factors to keep in mind is that air systems are usually a high volume system. mobile air compressors are frequently made using as much displacement for the compressor as for the drive engine. so you could trade off noise for size. the other side is that the storage medium is free to use and non polluting. |
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Post by wvengineer on Dec 20, 2017 2:34:38 GMT
The problem with air is it takes soo much energy to compress, and you loose a lot of that energy as heat. So you have very poor efficiency compared to other mediums.
I know that Ford was playing around with hydraulic hybrid systems on their pickup trucks back in the mid 2000's. looks like theyhave gone though several versions, but they do have options availabe for full size trucks. I'm not sure if it is a factory option, or a 3rd party that installs the system.
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Post by GTCGreg on Dec 20, 2017 3:02:01 GMT
The problem with air is it takes soo much energy to compress, and you loose a lot of that energy as heat. So you have very poor efficiency compared to other mediums. I know that Ford was playing around with hydraulic hybrid systems on their pickup trucks back in the mid 2000's. looks like theyhave gone though several versions, but they do have options availabe for full size trucks. I'm not sure if it is a factory option, or a 3rd party that installs the system. The Ford truck frame ambulances that New York City uses have electric dynamic breaking on them to save wear on the wheel brakes. It's a fairly large generator coupled directly to the drive shaft. When they apply the brake pedal, the generator just dumps it's load into a large resistor that dissipated the breaking energy as heat rather than wearing the brake pads. It's not regenerative as the energy is just wasted. As far as I understand, it's not a Ford system but an aftermarket add-on. |
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